From ef12e4030f54846e0bdaef8be58d3b0adac57486 Mon Sep 17 00:00:00 2001 From: Ran Date: Fri, 17 Jul 2020 17:08:28 +0800 Subject: [PATCH 1/8] system_tables: add column description for several tables Signed-off-by: Ran --- .../system-table-information-schema.md | 1227 +++++++++++++++++ 1 file changed, 1227 insertions(+) create mode 100644 system-tables/system-table-information-schema.md diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md new file mode 100644 index 0000000000000..81ccfffa92b88 --- /dev/null +++ b/system-tables/system-table-information-schema.md @@ -0,0 +1,1227 @@ +--- +title: Information Schema +summary: Learn how to use Information Schema in TiDB. +aliases: ['/docs/dev/system-tables/system-table-information-schema/','/docs/dev/reference/system-databases/information-schema/'] +--- + +# Information Schema + +As part of MySQL compatibility, TiDB supports a number of `INFORMATION_SCHEMA` tables. Many of these tables also have a corresponding `SHOW` command. The benefit of querying `INFORMATION_SCHEMA` is that it is possible to join between tables. + +## Fully Supported Information Schema Tables + +### ANALYZE_STATUS table + +The `ANALYZE_STATUS` table provides information about the running tasks that collect statistics and a limited number of history tasks. + +{{< copyable "sql" >}} + +```sql +select * from `ANALYZE_STATUS`; +``` + +``` ++--------------+------------+----------------+-------------------+----------------+---------------------+----------+ +| TABLE_SCHEMA | TABLE_NAME | PARTITION_NAME | JOB_INFO | PROCESSED_ROWS | START_TIME | STATE | ++--------------+------------+----------------+-------------------+----------------+---------------------+----------+ +| test | t | | analyze index idx | 2 | 2019-06-21 19:51:14 | finished | +| test | t | | analyze columns | 2 | 2019-06-21 19:51:14 | finished | +| test | t1 | p0 | analyze columns | 0 | 2019-06-21 19:51:15 | finished | +| test | t1 | p3 | analyze columns | 0 | 2019-06-21 19:51:15 | finished | +| test | t1 | p1 | analyze columns | 0 | 2019-06-21 19:51:15 | finished | +| test | t1 | p2 | analyze columns | 1 | 2019-06-21 19:51:15 | finished | ++--------------+------------+----------------+-------------------+----------------+---------------------+----------+ +6 rows in set +``` + +### CHARACTER_SETS table + +The `CHARACTER_SETS` table provides information about [character sets](/character-set-and-collation.md). Currently, TiDB only supports some of the character sets. + +{{< copyable "sql" >}} + +```sql +SELECT * FROM character_sets; +``` + +``` ++--------------------+----------------------+---------------+--------+ +| CHARACTER_SET_NAME | DEFAULT_COLLATE_NAME | DESCRIPTION | MAXLEN | ++--------------------+----------------------+---------------+--------+ +| utf8 | utf8_bin | UTF-8 Unicode | 3 | +| utf8mb4 | utf8mb4_bin | UTF-8 Unicode | 4 | +| ascii | ascii_bin | US ASCII | 1 | +| latin1 | latin1_bin | Latin1 | 1 | +| binary | binary | binary | 1 | ++--------------------+----------------------+---------------+--------+ +5 rows in set (0.00 sec) +``` + +The description of columns in the `CHARACTER_SETS` table is as follows: + +* `CHARACTER_SET_NAME`: The name of the character set. +* `DEFAULT_COLLATE_NAME`：The default collation name of the character set. +* `DESCRIPTION`：The description of the character set +* `MAXLEN`：The maximum length required to store a character in this character set. + +### COLLATIONS table + +The `COLLATIONS` table provides a list of collations that correspond to character sets in the `CHARACTER_SETS` table. Currently this table is included only for compatibility with MySQL, as TiDB only supports binary collation: + +{{< copyable "sql" >}} + +```sql +SELECT * FROM collations WHERE character_set_name='utf8mb4'; +``` + +``` ++------------------------+--------------------+------+------------+-------------+---------+ +| COLLATION_NAME | CHARACTER_SET_NAME | ID | IS_DEFAULT | IS_COMPILED | SORTLEN | ++------------------------+--------------------+------+------------+-------------+---------+ +| utf8mb4_general_ci | utf8mb4 | 45 | Yes | Yes | 1 | +| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 | +| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 | +| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 1 | +| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 1 | +| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 1 | +| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 1 | +| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 1 | +| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 1 | +| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 1 | +| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 1 | +| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 1 | +| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 1 | +| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 1 | +| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 1 | +| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 1 | +| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 1 | +| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 1 | +| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 1 | +| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 1 | +| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 1 | +| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 1 | +| utf8mb4_german2_ci | utf8mb4 | 244 | | Yes | 1 | +| utf8mb4_croatian_ci | utf8mb4 | 245 | | Yes | 1 | +| utf8mb4_unicode_520_ci | utf8mb4 | 246 | | Yes | 1 | +| utf8mb4_vietnamese_ci | utf8mb4 | 247 | | Yes | 1 | ++------------------------+--------------------+------+------------+-------------+---------+ +26 rows in set (0.00 sec) +``` + +The description of columns in the `COLLATION` table is as follows: + +* `COLLATION_NAME`: The name of the collation. +* `CHARACTER_SET_NAME`: The name of the character set which the collation belongs to. +* `ID`: The ID of the collation. +* `IS_DEFAULT`: Whether this collation is the default collation of the character set it belongs to. +* `IS_COMPILED`: Whether the character set is compiled into the server. +* `SORTLEN`: The minimum length of memory allocated when the collation sorts characters. + +### COLLATION_CHARACTER_SET_APPLICABILITY table + +The `COLLATION_CHARACTER_SET_APPLICABILITY` table maps collations to the applicable character set name. Similar to the `COLLATIONS` table, it is included only for compatibility with MySQL: + +{{< copyable "sql" >}} + +```sql +SELECT * FROM collation_character_set_applicability WHERE character_set_name='utf8mb4'; +``` + ++----------------+--------------------+ +| COLLATION_NAME | CHARACTER_SET_NAME | ++----------------+--------------------+ +| utf8mb4_bin | utf8mb4 | ++----------------+--------------------+ + +The description of columns in the `COLLATION_CHARACTER_SET_APPLICABILITY` table is as follows: + +* `COLLATION_NAME`: The name of the collation. +* `CHARACTER_SET_NAME`: The name of the character set which the collation belongs to. + +### COLUMNS table + +The `COLUMNS` table provides detailed information about columns in tables: + +{{< copyable "sql" >}} + +```sql +CREATE TABLE test.t1 (a int); +``` + +``` +1 row in set (0.01 sec) +``` + +{{< copyable "sql" >}} + +```sql +SELECT * FROM information_schema.columns WHERE table_schema='test' AND TABLE_NAME='t1'; +``` + +``` +*************************** 1. row *************************** + TABLE_CATALOG: def + TABLE_SCHEMA: test + TABLE_NAME: t1 + COLUMN_NAME: a + ORDINAL_POSITION: 1 + COLUMN_DEFAULT: NULL + IS_NULLABLE: YES + DATA_TYPE: int +CHARACTER_MAXIMUM_LENGTH: NULL + CHARACTER_OCTET_LENGTH: NULL + NUMERIC_PRECISION: 11 + NUMERIC_SCALE: 0 + DATETIME_PRECISION: NULL + CHARACTER_SET_NAME: NULL + COLLATION_NAME: NULL + COLUMN_TYPE: int(11) + COLUMN_KEY: + EXTRA: + PRIVILEGES: select,insert,update,references + COLUMN_COMMENT: + GENERATION_EXPRESSION: +1 row in set (0.01 sec) +``` + +The description of columns in the `COLUMNS` table is as follows: + +* `TABLE_CATALOG`: The name of the catalog to which the table with the column belongs. The value is always `def`. +* `TABLE_SCHEMA`: The name of the schema in which the table with the column is located. +* `TABLE_NAME`: The name of the table with the column. +* `COLUMN_NAME`: The name of the column. +* `ORDINAL_POSITION`: The position of the column in the table. +* `COLUMN_DEFAULT`: The default value of the column. If the explicit default value is `NULL`, or if the column definition does not include the `default` clause, this value is `NULL`. +* `IS_NULLABLE`: Whether the column is nullable. If the column can store null values, this value is `YES`; otherwise, it is `NO`. +* `DATA_TYPE`: The type of data in the column. +* `CHARACTER_MAXIMUM_LENGTH`: For string columns, the maximum length in characters. +* `CHARACTER_OCTET_LENGTH`: For string columns, the maximum length in bytes. +* `NUMERIC_PRECISION`: The numeric precision of a number-type column. +* `NUMERIC_SCALE`: The numeric scale of a number-type column. +* `DATETIME_PRECISION`: For time-type columns, the fractional seconds precision. +* `CHARACTER_SET_NAME`: The name of the character set of a string column. +* `COLLATION_NAME`: The name of the collation of a string column. +* `COLUMN_TYPE`: The column type. +* `COLUMN_KEY`: Whether this column is indexed. This field might have the following values: + * Empty: This column is not indexed, or this column is indexed and is the second column in a multi-column non-unique index. + * `PRI`: This column is the primary key or one of multiple primary keys. + * `UNI`: This column is the first column of the unique index. + * `MUL`: The column is the first column of a non-unique index, in which a given value is allowed to occur for multiple times. +* `EXTRA`: Any additional information of the given column. +* `PRIVILEGES`: The privilege that the current user has on this column. Currently, this value is fixed in TiDB, and is always `select,insert,update,references`. +* `COLUMN_COMMENT`: Comments contained in the column definition. +* `GENERATION_EXPRESSION`: For generated columns, this value displays the expression used to calculate the column value. For non-generated columns, the value is empty. + +The corresponding `SHOW` statement is as follows: + +{{< copyable "sql" >}} + +```sql +SHOW COLUMNS FROM t1 FROM test; +``` + +``` ++-------+---------+------+------+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++-------+---------+------+------+---------+-------+ +| a | int(11) | YES | | NULL | | ++-------+---------+------+------+---------+-------+ +1 row in set (0.00 sec) +``` + +### ENGINES table + +The `ENGINES` table provides information about storage engines. For compatibility, TiDB will always describe InnoDB as the only supported engine. In addition, other column values in the `ENGINES` table are also fixed values. + +{{< copyable "sql" >}} + +```sql +SELECT * FROM engines; +``` + +``` +*************************** 1. row *************************** + ENGINE: InnoDB + SUPPORT: DEFAULT + COMMENT: Supports transactions, row-level locking, and foreign keys +TRANSACTIONS: YES + XA: YES + SAVEPOINTS: YES +1 row in set (0.00 sec) +``` + +The description of columns in the `ENGINES` table is as follows: + +* `ENGINES`: The name of the storage engine. +* `SUPPORT`: The level of support that the server has on the storage engine. In TiDB, the value is always `DEFAULT`. +* `COMMENT`: The brief comment on the storage engine. +* `TRANSACTIONS`：Whether the storage engine supports transactions. +* `XA`: Whether the storage engine supports XA transactions. +* `SAVEPOINTS`: Whether the storage engine supports `savepoints`. + +### KEY_COLUMN_USAGE table + +The `KEY_COLUMN_USAGE` table describes the key constraints of the columns, such as the primary key constraint: + +{{< copyable "sql" >}} + +```sql +SELECT * FROM key_column_usage WHERE table_schema='mysql' and table_name='user'; +``` + +``` +*************************** 1. row *************************** + CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: PRIMARY + TABLE_CATALOG: def + TABLE_SCHEMA: mysql + TABLE_NAME: user + COLUMN_NAME: Host + ORDINAL_POSITION: 1 +POSITION_IN_UNIQUE_CONSTRAINT: NULL + REFERENCED_TABLE_SCHEMA: NULL + REFERENCED_TABLE_NAME: NULL + REFERENCED_COLUMN_NAME: NULL +*************************** 2. row *************************** + CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: PRIMARY + TABLE_CATALOG: def + TABLE_SCHEMA: mysql + TABLE_NAME: user + COLUMN_NAME: User + ORDINAL_POSITION: 2 +POSITION_IN_UNIQUE_CONSTRAINT: NULL + REFERENCED_TABLE_SCHEMA: NULL + REFERENCED_TABLE_NAME: NULL + REFERENCED_COLUMN_NAME: NULL +2 rows in set (0.00 sec) +``` + +The description of columns in the `KEY_COLUMN_USAGE` table is as follows: + +* `CONSTRAINT_CATALOG`: The name of the catalog to which the constraint belongs. The value is always `def`. +* `CONSTRAINT_SCHEMA`: The name of the schema to which the constraint belongs. +* `CONSTRAINT_NAME`: The name of the constraint. +* `TABLE_CATALOG`: The name of the catalog to which the table belongs. The value is always `def`. +* `TABLE_SCHEMA`: The name of the schema to which the table belongs. +* `TABLE_NAME`: The name of the table with constraints. +* `COLUMN_NAME`: The name of the column with constraints. +* `ORDINAL_POSITION`: The position of the column in the constraint, rather than in the table. The position number starts from `1`. +* `POSITION_IN_UNIQUE_CONSTRAINT`: The unique constraint and the primary key constraint are empty. For foreign key constraints, this column is the position of the referenced table's key. +* `REFERENCED_TABLE_SCHEMA`: The name of the schema referenced by the constraint. Currently in TiDB, the value of this column in all constraints is `nil`, except for the foreign key constraint. +* `REFERENCED_TABLE_NAME`: The name of the table referenced by the constraint. Currently in TiDB, the value of this column in all constraints is `nil`, except for the foreign key constraint. +* `REFERENCED_COLUMN_NAME`: The name of the column referenced by the constraint. Currently in TiDB, the value of this column in all constraints is `nil`, except for the foreign key constraint. + +### PROCESSLIST table + +`PROCESSLIST`, just like `show processlist`, is used to view the requests that are being handled. + +The `PROCESSLIST` table has a `MEM` column that `show processlist` does not have. `MEM` means the occupied memory of the requests being handled, and its unit is `byte`. + +``` ++----+------+------+--------------------+---------+------+-------+---------------------------+-----+ +| ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | MEM | ++----+------+------+--------------------+---------+------+-------+---------------------------+-----+ +| 1 | root | ::1 | INFORMATION_SCHEMA | Query | 0 | 2 | select * from PROCESSLIST | 0 | ++----+------+------+--------------------+---------+------+-------+---------------------------+-----+ +``` + +### SCHEMATA table + +The `SCHEMATA` table provides information about databases. The table data is equivalent to the result of the `SHOW DATABASES` statement: + +{{< copyable "sql" >}} + +```sql +select * from SCHEMATA; +``` + +``` +*************************** 1. row *************************** + CATALOG_NAME: def + SCHEMA_NAME: INFORMATION_SCHEMA +DEFAULT_CHARACTER_SET_NAME: utf8mb4 + DEFAULT_COLLATION_NAME: utf8mb4_bin + SQL_PATH: NULL +*************************** 2. row *************************** + CATALOG_NAME: def + SCHEMA_NAME: mysql +DEFAULT_CHARACTER_SET_NAME: utf8mb4 + DEFAULT_COLLATION_NAME: utf8mb4_bin + SQL_PATH: NULL +*************************** 3. row *************************** + CATALOG_NAME: def + SCHEMA_NAME: PERFORMANCE_SCHEMA +DEFAULT_CHARACTER_SET_NAME: utf8mb4 + DEFAULT_COLLATION_NAME: utf8mb4_bin + SQL_PATH: NULL +*************************** 4. row *************************** + CATALOG_NAME: def + SCHEMA_NAME: test +DEFAULT_CHARACTER_SET_NAME: utf8mb4 + DEFAULT_COLLATION_NAME: utf8mb4_bin + SQL_PATH: NULL +4 rows in set (0.00 sec) +``` + +## CLUSTER_PROCESSLIST + +`CLUSTER_PROCESSLIST` is the cluster system table corresponding to `PROCESSLIST`. It is used to query the `PROCESSLIST` information of all TiDB nodes in the cluster. The table schema of `CLUSTER_PROCESSLIST` has one more column than `PROCESSLIST`, the `INSTANCE` column, which stores the address of the TiDB node this row of data is from. + +{{< copyable "sql" >}} + +```sql +SELECT * FROM information_schema.cluster_processlist; +``` + +``` ++-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ +| INSTANCE | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | MEM | TxnStart | ++-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ +| 10.0.1.22:10080 | 150 | u1 | 10.0.1.1 | test | Query | 0 | autocommit | select count(*) from usertable | 372 | 05-28 03:54:21.230(416976223923077223) | +| 10.0.1.22:10080 | 138 | root | 10.0.1.1 | test | Query | 0 | autocommit | SELECT * FROM information_schema.cluster_processlist | 0 | 05-28 03:54:21.230(416976223923077220) | +| 10.0.1.22:10080 | 151 | u1 | 10.0.1.1 | test | Query | 0 | autocommit | select count(*) from usertable | 372 | 05-28 03:54:21.230(416976223923077224) | +| 10.0.1.21:10080 | 15 | u2 | 10.0.1.1 | test | Query | 0 | autocommit | select max(field0) from usertable | 496 | 05-28 03:54:21.230(416976223923077222) | +| 10.0.1.21:10080 | 14 | u2 | 10.0.1.1 | test | Query | 0 | autocommit | select max(field0) from usertable | 496 | 05-28 03:54:21.230(416976223923077225) | ++-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ +``` + +### SESSION_VARIABLES table + +The `SESSION_VARIABLES` table provides information about session variables. The table data is similar to the result of the `SHOW SESSION VARIABLES` statement: + +{{< copyable "sql" >}} + +```sql +SELECT * FROM session_variables LIMIT 10; +``` + +``` ++----------------------------------+----------------------+ +| VARIABLE_NAME | VARIABLE_VALUE | ++----------------------------------+----------------------+ +| max_write_lock_count | 18446744073709551615 | +| server_id_bits | 32 | +| net_read_timeout | 30 | +| innodb_online_alter_log_max_size | 134217728 | +| innodb_optimize_fulltext_only | OFF | +| max_join_size | 18446744073709551615 | +| innodb_read_io_threads | 4 | +| session_track_gtids | OFF | +| have_ssl | DISABLED | +| max_binlog_cache_size | 18446744073709547520 | ++----------------------------------+----------------------+ +10 rows in set (0.00 sec) +``` + +## SLOW_QUERY table + +The `SLOW_QUERY` table provides the slow query information of the current node, which is the parsing result of the TiDB slow log file. The column names in the table are corresponding to the field names in the slow log. For how to use this table to identify problematic statements and improve query performance, see [Slow Query Log Document](/identify-slow-queries.md). + +{{< copyable "sql" >}} + +```sql +desc information_schema.slow_query; +``` + +```sql ++---------------------------+---------------------+------+-----+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++---------------------------+---------------------+------+-----+---------+-------+ +| Time | timestamp unsigned | YES | | | | +| Txn_start_ts | bigint(20) unsigned | YES | | | | +| User | varchar(64) | YES | | | | +| Host | varchar(64) | YES | | | | +| Conn_ID | bigint(20) unsigned | YES | | | | +| Query_time | double unsigned | YES | | | | +| Parse_time | double unsigned | YES | | | | +| Compile_time | double unsigned | YES | | | | +| Prewrite_time | double unsigned | YES | | | | +| Wait_prewrite_binlog_time | double unsigned | YES | | | | +| Commit_time | double unsigned | YES | | | | +| Get_commit_ts_time | double unsigned | YES | | | | +| Commit_backoff_time | double unsigned | YES | | | | +| Backoff_types | varchar(64) | YES | | | | +| Resolve_lock_time | double unsigned | YES | | | | +| Local_latch_wait_time | double unsigned | YES | | | | +| Write_keys | bigint(22) unsigned | YES | | | | +| Write_size | bigint(22) unsigned | YES | | | | +| Prewrite_region | bigint(22) unsigned | YES | | | | +| Txn_retry | bigint(22) unsigned | YES | | | | +| Process_time | double unsigned | YES | | | | +| Wait_time | double unsigned | YES | | | | +| Backoff_time | double unsigned | YES | | | | +| LockKeys_time | double unsigned | YES | | | | +| Request_count | bigint(20) unsigned | YES | | | | +| Total_keys | bigint(20) unsigned | YES | | | | +| Process_keys | bigint(20) unsigned | YES | | | | +| DB | varchar(64) | YES | | | | +| Index_names | varchar(100) | YES | | | | +| Is_internal | tinyint(1) unsigned | YES | | | | +| Digest | varchar(64) | YES | | | | +| Stats | varchar(512) | YES | | | | +| Cop_proc_avg | double unsigned | YES | | | | +| Cop_proc_p90 | double unsigned | YES | | | | +| Cop_proc_max | double unsigned | YES | | | | +| Cop_proc_addr | varchar(64) | YES | | | | +| Cop_wait_avg | double unsigned | YES | | | | +| Cop_wait_p90 | double unsigned | YES | | | | +| Cop_wait_max | double unsigned | YES | | | | +| Cop_wait_addr | varchar(64) | YES | | | | +| Mem_max | bigint(20) unsigned | YES | | | | +| Succ | tinyint(1) unsigned | YES | | | | +| Plan_from_cache | tinyint(1) | YES | | | | +| Plan | longblob unsigned | YES | | | | +| Plan_digest | varchar(128) | YES | | | | +| Prev_stmt | longblob unsigned | YES | | | | +| Query | longblob unsigned | YES | | | | ++---------------------------+---------------------+------+-----+---------+-------+ +``` + +## CLUSTER_SLOW_QUERY table + +The `CLUSTER_SLOW_QUERY` table provides the slow query information of all nodes in the cluster, which is the parsing result of the TiDB slow log files. You can use the `CLUSTER_SLOW_QUERY` table the way you do with [`SLOW_QUERY`](#slow_query-table). The table schema of the `CLUSTER_SLOW_QUERY` table differs from that of the `SLOW_QUERY` table in that an `INSTANCE` column is added to `CLUSTER_SLOW_QUERY`. The `INSTANCE` column represents the TiDB node address of the row information on the slow query. For how to use this table to identify problematic statements and improve query performance, see [Slow Query Log Document](/identify-slow-queries.md). + +{{< copyable "sql" >}} + +```sql +desc information_schema.cluster_slow_query; +``` + +```sql ++---------------------------+---------------------+------+-----+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++---------------------------+---------------------+------+-----+---------+-------+ +| INSTANCE | varchar(64) | YES | | | | +| Time | timestamp unsigned | YES | | | | +| Txn_start_ts | bigint(20) unsigned | YES | | | | +| User | varchar(64) | YES | | | | +| Host | varchar(64) | YES | | | | +| Conn_ID | bigint(20) unsigned | YES | | | | +| Query_time | double unsigned | YES | | | | +| Parse_time | double unsigned | YES | | | | +| Compile_time | double unsigned | YES | | | | +| Prewrite_time | double unsigned | YES | | | | +| Wait_prewrite_binlog_time | double unsigned | YES | | | | +| Commit_time | double unsigned | YES | | | | +| Get_commit_ts_time | double unsigned | YES | | | | +| Commit_backoff_time | double unsigned | YES | | | | +| Backoff_types | varchar(64) | YES | | | | +| Resolve_lock_time | double unsigned | YES | | | | +| Local_latch_wait_time | double unsigned | YES | | | | +| Write_keys | bigint(22) unsigned | YES | | | | +| Write_size | bigint(22) unsigned | YES | | | | +| Prewrite_region | bigint(22) unsigned | YES | | | | +| Txn_retry | bigint(22) unsigned | YES | | | | +| Process_time | double unsigned | YES | | | | +| Wait_time | double unsigned | YES | | | | +| Backoff_time | double unsigned | YES | | | | +| LockKeys_time | double unsigned | YES | | | | +| Request_count | bigint(20) unsigned | YES | | | | +| Total_keys | bigint(20) unsigned | YES | | | | +| Process_keys | bigint(20) unsigned | YES | | | | +| DB | varchar(64) | YES | | | | +| Index_names | varchar(100) | YES | | | | +| Is_internal | tinyint(1) unsigned | YES | | | | +| Digest | varchar(64) | YES | | | | +| Stats | varchar(512) | YES | | | | +| Cop_proc_avg | double unsigned | YES | | | | +| Cop_proc_p90 | double unsigned | YES | | | | +| Cop_proc_max | double unsigned | YES | | | | +| Cop_proc_addr | varchar(64) | YES | | | | +| Cop_wait_avg | double unsigned | YES | | | | +| Cop_wait_p90 | double unsigned | YES | | | | +| Cop_wait_max | double unsigned | YES | | | | +| Cop_wait_addr | varchar(64) | YES | | | | +| Mem_max | bigint(20) unsigned | YES | | | | +| Succ | tinyint(1) unsigned | YES | | | | +| Plan_from_cache | tinyint(1) | YES | | | | +| Plan | longblob unsigned | YES | | | | +| Plan_digest | varchar(128) | YES | | | | +| Prev_stmt | longblob unsigned | YES | | | | +| Query | longblob unsigned | YES | | | | ++---------------------------+---------------------+------+-----+---------+-------+ +``` + +When the cluster system table is queried, TiDB does not obtain data from all nodes, but pushes down the related calculation to other nodes. The execution plan is as follows: + +{{< copyable "sql" >}} + +```sql +desc select count(*) from information_schema.cluster_slow_query where user = 'u1'; +``` + +``` ++--------------------------+----------+-----------+--------------------------+------------------------------------------------------+ +| id | estRows | task | access object | operator info | ++--------------------------+----------+-----------+--------------------------+------------------------------------------------------+ +| StreamAgg_20 | 1.00 | root | | funcs:count(Column#53)->Column#51 | +| └─TableReader_21 | 1.00 | root | | data:StreamAgg_9 | +| └─StreamAgg_9 | 1.00 | cop[tidb] | | funcs:count(1)->Column#53 | +| └─Selection_19 | 10.00 | cop[tidb] | | eq(information_schema.cluster_slow_query.user, "u1") | +| └─TableFullScan_18 | 10000.00 | cop[tidb] | table:CLUSTER_SLOW_QUERY | keep order:false, stats:pseudo | ++--------------------------+----------+-----------+--------------------------+------------------------------------------------------+ +``` + +In the above execution plan, the `user = u1` condition is pushed down to other (`cop`) TiDB nodes, and the aggregate operator is also pushed down (the `StreamAgg` operator in the graph). + +Currently, because statistics of the system tables are not collected, sometimes some aggregation operators cannot be pushed down, which results in slow execution. In this case, you can manually specify the SQL HINT to push down the aggregation operators. For example: + +{{< copyable "sql" >}} + +```sql +select /*+ AGG_TO_COP() */ count(*) from information_schema.cluster_slow_query group by user; +``` + +### STATISTICS table + +The `STATISTICS` table provides information about table indexes: + +{{< copyable "sql" >}} + +```sql +desc statistics; +``` + +``` ++---------------+---------------+------+------+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++---------------+---------------+------+------+---------+-------+ +| TABLE_CATALOG | varchar(512) | YES | | NULL | | +| TABLE_SCHEMA | varchar(64) | YES | | NULL | | +| TABLE_NAME | varchar(64) | YES | | NULL | | +| NON_UNIQUE | varchar(1) | YES | | NULL | | +| INDEX_SCHEMA | varchar(64) | YES | | NULL | | +| INDEX_NAME | varchar(64) | YES | | NULL | | +| SEQ_IN_INDEX | bigint(2) | YES | | NULL | | +| COLUMN_NAME | varchar(21) | YES | | NULL | | +| COLLATION | varchar(1) | YES | | NULL | | +| CARDINALITY | bigint(21) | YES | | NULL | | +| SUB_PART | bigint(3) | YES | | NULL | | +| PACKED | varchar(10) | YES | | NULL | | +| NULLABLE | varchar(3) | YES | | NULL | | +| INDEX_TYPE | varchar(16) | YES | | NULL | | +| COMMENT | varchar(16) | YES | | NULL | | +| INDEX_COMMENT | varchar(1024) | YES | | NULL | | +| IS_VISIBLE | varchar(3) | YES | | NULL | | +| Expression | varchar(64) | YES | | NULL | | ++---------------+---------------+------+------+---------+-------+ +``` + +The following statements are equivalent: + +```sql +SELECT * FROM INFORMATION_SCHEMA.STATISTICS + WHERE table_name = 'tbl_name' + AND table_schema = 'db_name' + +SHOW INDEX + FROM tbl_name + FROM db_name +``` + +### TABLES table + +The `TABLES` table provides information about tables in databases: + +{{< copyable "sql" >}} + +```sql +SELECT * FROM tables WHERE table_schema='mysql' AND table_name='user'; +``` + +``` +*************************** 1. row *************************** + TABLE_CATALOG: def + TABLE_SCHEMA: mysql + TABLE_NAME: user + TABLE_TYPE: BASE TABLE + ENGINE: InnoDB + VERSION: 10 + ROW_FORMAT: Compact + TABLE_ROWS: 0 + AVG_ROW_LENGTH: 0 + DATA_LENGTH: 0 + MAX_DATA_LENGTH: 0 + INDEX_LENGTH: 0 + DATA_FREE: 0 + AUTO_INCREMENT: 0 + CREATE_TIME: 2019-03-29 09:17:27 + UPDATE_TIME: NULL + CHECK_TIME: NULL + TABLE_COLLATION: utf8mb4_bin + CHECKSUM: NULL + CREATE_OPTIONS: + TABLE_COMMENT: + TIDB_TABLE_ID: 5 +TIDB_ROW_ID_SHARDING_INFO: NULL +1 row in set (0.00 sec) +``` + +The following statements are equivalent: + +```sql +SELECT table_name FROM INFORMATION_SCHEMA.TABLES + WHERE table_schema = 'db_name' + [AND table_name LIKE 'wild'] + +SHOW TABLES + FROM db_name + [LIKE 'wild'] +``` + +Most of the information in the table is the same as MySQL. Only two columns are newly defined by TiDB: + +* `TIDB_TABLE_ID`: to indicate the internal ID of a table. This ID is unique in a TiDB cluster. +* `TIDDB_ROW_ID_SHARDING_INFO`: to indicate the sharding type of a table. The possible values are as follows: + - `"NOT_SHARDED"`: the table is not sharded. + - `"NOT_SHARDED(PK_IS_HANDLE)"`: the table that defines an integer Primary Key as its row id is not sharded. + - `"PK_AUTO_RANDOM_BITS={bit_number}"`: the table that defines an integer Primary Key as its row id is sharded because the Primary Key is assigned with `AUTO_RANDOM` attribute. + - `"SHARD_BITS={bit_number}"`: the table is sharded using `SHARD_ROW_ID_BITS={bit_number}`. + - NULL: the table is a system table or view, and thus cannot be sharded. + +### TABLE_CONSTRAINTS table + +The `TABLE_CONSTRAINTS` table describes which tables have constraints: + +{{< copyable "sql" >}} + +```sql +SELECT * FROM table_constraints WHERE constraint_type='UNIQUE'; +``` + +``` +*************************** 1. row *************************** +CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: name + TABLE_SCHEMA: mysql + TABLE_NAME: help_topic + CONSTRAINT_TYPE: UNIQUE +*************************** 2. row *************************** +CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: tbl + TABLE_SCHEMA: mysql + TABLE_NAME: stats_meta + CONSTRAINT_TYPE: UNIQUE +*************************** 3. row *************************** +CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: tbl + TABLE_SCHEMA: mysql + TABLE_NAME: stats_histograms + CONSTRAINT_TYPE: UNIQUE +*************************** 4. row *************************** +CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: tbl + TABLE_SCHEMA: mysql + TABLE_NAME: stats_buckets + CONSTRAINT_TYPE: UNIQUE +*************************** 5. row *************************** +CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: delete_range_index + TABLE_SCHEMA: mysql + TABLE_NAME: gc_delete_range + CONSTRAINT_TYPE: UNIQUE +*************************** 6. row *************************** +CONSTRAINT_CATALOG: def + CONSTRAINT_SCHEMA: mysql + CONSTRAINT_NAME: delete_range_done_index + TABLE_SCHEMA: mysql + TABLE_NAME: gc_delete_range_done + CONSTRAINT_TYPE: UNIQUE +6 rows in set (0.00 sec) +``` + +- The `CONSTRAINT_TYPE` value can be `UNIQUE`, `PRIMARY KEY`, or `FOREIGN KEY`. +- The `UNIQUE` and `PRIMARY KEY` information is similar to the result of the `SHOW INDEX` statement. + +### TIDB_HOT_REGIONS table + +The `TIDB_HOT_REGIONS` table provides information about hotspot Regions. + +{{< copyable "sql" >}} + +```sql +desc TIDB_HOT_REGIONS; +``` + +``` ++----------------+---------------------+------+-----+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++----------------+---------------------+------+-----+---------+-------+ +| TABLE_ID | bigint(21) unsigned | YES | | | | +| INDEX_ID | bigint(21) unsigned | YES | | | | +| DB_NAME | varchar(64) | YES | | | | +| TABLE_NAME | varchar(64) | YES | | | | +| INDEX_NAME | varchar(64) | YES | | | | +| TYPE | varchar(64) | YES | | | | +| MAX_HOT_DEGREE | bigint(21) unsigned | YES | | | | +| REGION_COUNT | bigint(21) unsigned | YES | | | | +| FLOW_BYTES | bigint(21) unsigned | YES | | | | ++----------------+---------------------+------+-----+---------+-------+ +``` + +### TIDB_INDEXES table + +The `TIDB_INDEXES` table provides the INDEX information of all tables. + +{{< copyable "sql" >}} + +```sql +desc TIDB_INDEXES; +``` + +``` ++---------------+---------------------+------+-----+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++---------------+---------------------+------+-----+---------+-------+ +| TABLE_SCHEMA | varchar(64) | YES | | | | +| TABLE_NAME | varchar(64) | YES | | | | +| NON_UNIQUE | bigint(21) unsigned | YES | | | | +| KEY_NAME | varchar(64) | YES | | | | +| SEQ_IN_INDEX | bigint(21) unsigned | YES | | | | +| COLUMN_NAME | varchar(64) | YES | | | | +| SUB_PART | bigint(21) unsigned | YES | | | | +| INDEX_COMMENT | varchar(2048) | YES | | | | +| INDEX_ID | bigint(21) unsigned | YES | | | | ++---------------+---------------------+------+-----+---------+-------+ +``` + +### TIKV_REGION_PEERS table + +The `TIKV_REGION_PEERS` table provides the peer information of all Regions. + +{{< copyable "sql" >}} + +```sql +desc TIKV_REGION_PEERS; +``` + +``` ++--------------+---------------------+------+-----+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++--------------+---------------------+------+-----+---------+-------+ +| REGION_ID | bigint(21) unsigned | YES | | | | +| PEER_ID | bigint(21) unsigned | YES | | | | +| STORE_ID | bigint(21) unsigned | YES | | | | +| IS_LEARNER | tinyint(1) unsigned | YES | | | | +| IS_LEADER | tinyint(1) unsigned | YES | | | | +| STATUS | varchar(10) | YES | | | | +| DOWN_SECONDS | bigint(21) unsigned | YES | | | | ++--------------+---------------------+------+-----+---------+-------+ +``` + +### TIKV_REGION_STATUS table + +The `TIKV_REGION_STATUS` table provides the status information of all Regions. + +{{< copyable "sql" >}} + +```sql +desc TIKV_REGION_STATUS; +``` + +``` ++------------------+---------------------+------+-----+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++------------------+---------------------+------+-----+---------+-------+ +| REGION_ID | bigint(21) unsigned | YES | | | | +| START_KEY | text | YES | | | | +| END_KEY | text | YES | | | | +| EPOCH_CONF_VER | bigint(21) unsigned | YES | | | | +| EPOCH_VERSION | bigint(21) unsigned | YES | | | | +| WRITTEN_BYTES | bigint(21) unsigned | YES | | | | +| READ_BYTES | bigint(21) unsigned | YES | | | | +| APPROXIMATE_SIZE | bigint(21) unsigned | YES | | | | +| APPROXIMATE_KEYS | bigint(21) unsigned | YES | | | | ++------------------+---------------------+------+-----+---------+-------+ +``` + +### TIKV_STORE_STATUS table + +The `TIKV_STORE_STATUS` table provides the status information of all TiKV Stores. + +{{< copyable "sql" >}} + +```sql +desc TIKV_STORE_STATUS; +``` + +``` ++-------------------+---------------------+------+-----+---------+-------+ +| Field | Type | Null | Key | Default | Extra | ++-------------------+---------------------+------+-----+---------+-------+ +| STORE_ID | bigint(21) unsigned | YES | | | | +| ADDRESS | varchar(64) | YES | | | | +| STORE_STATE | bigint(21) unsigned | YES | | | | +| STORE_STATE_NAME | varchar(64) | YES | | | | +| LABEL | json unsigned | YES | | | | +| VERSION | varchar(64) | YES | | | | +| CAPACITY | varchar(64) | YES | | | | +| AVAILABLE | varchar(64) | YES | | | | +| LEADER_COUNT | bigint(21) unsigned | YES | | | | +| LEADER_WEIGHT | bigint(21) unsigned | YES | | | | +| LEADER_SCORE | bigint(21) unsigned | YES | | | | +| LEADER_SIZE | bigint(21) unsigned | YES | | | | +| REGION_COUNT | bigint(21) unsigned | YES | | | | +| REGION_WEIGHT | bigint(21) unsigned | YES | | | | +| REGION_SCORE | bigint(21) unsigned | YES | | | | +| REGION_SIZE | bigint(21) unsigned | YES | | | | +| START_TS | datetime unsigned | YES | | | | +| LAST_HEARTBEAT_TS | datetime unsigned | YES | | | | +| UPTIME | varchar(64) | YES | | | | ++-------------------+---------------------+------+-----+---------+-------+ +``` + +### USER_PRIVILEGES table + +The `USER_PRIVILEGES` table provides information about global privileges. This information comes from the `mysql.user` system table: + +{{< copyable "sql" >}} + +```sql +desc USER_PRIVILEGES; +``` + +``` ++----------------|--------------|------|------|---------|-------+ +| Field | Type | Null | Key | Default | Extra | ++----------------|--------------|------|------|---------|-------+ +| GRANTEE | varchar(81) | YES | | NULL | | +| TABLE_CATALOG | varchar(512) | YES | | NULL | | +| PRIVILEGE_TYPE | varchar(64) | YES | | NULL | | +| IS_GRANTABLE | varchar(3) | YES | | NULL | | ++----------------|--------------|------|------|---------|-------+ +4 rows in set (0.00 sec) +``` + +### VIEWS table + +The `VIEWS` table provides information about SQL views: + +{{< copyable "sql" >}} + +```sql +create view test.v1 as select 1; +``` + +``` +Query OK, 0 rows affected (0.00 sec) +``` + +{{< copyable "sql" >}} + +```sql +select * from views; +``` + +``` +*************************** 1. row *************************** + TABLE_CATALOG: def + TABLE_SCHEMA: test + TABLE_NAME: v1 + VIEW_DEFINITION: select 1 + CHECK_OPTION: CASCADED + IS_UPDATABLE: NO + DEFINER: root@127.0.0.1 + SECURITY_TYPE: DEFINER +CHARACTER_SET_CLIENT: utf8 +COLLATION_CONNECTION: utf8_general_ci +1 row in set (0.00 sec) +``` + +## TIDB\_INDEXES table + +The `TIDB_INDEXES` table provides index-related information. + +{{< copyable "sql" >}} + +```sql +desc tidb_indexes\G +``` + +``` +*************************** 1. row *************************** + Table: TIDB_INDEXES +Create Table: CREATE TABLE `TIDB_INDEXES` ( + `TABLE_SCHEMA` varchar(64) DEFAULT NULL, + `TABLE_NAME` varchar(64) DEFAULT NULL, + `NON_UNIQUE` bigint(21) unsigned DEFAULT NULL, + `KEY_NAME` varchar(64) DEFAULT NULL, + `SEQ_IN_INDEX` bigint(21) unsigned DEFAULT NULL, + `COLUMN_NAME` varchar(64) DEFAULT NULL, + `SUB_PART` bigint(21) unsigned DEFAULT NULL, + `INDEX_COMMENT` varchar(2048) DEFAULT NULL, + `INDEX_ID` bigint(21) unsigned DEFAULT NULL +) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin +1 row in set (0.00 sec) +``` + +`INDEX_ID` is the unique ID that TiDB allocates for each index. It can be used to do a join operation with `INDEX_ID` obtained from another table or API. + +For example, you can obtain `TABLE_ID` and `INDEX_ID` that are involved in some slow query in the [`SLOW_QUERY` table](#slow_query-table) and then obtain the specific index information using the following SQL statements: + +```sql +select + tidb_indexes.* +from + tidb_indexes, + tables +where + tidb_indexes.table_schema = tables.table_schema + and tidb_indexes.table_name = tidb_indexes.table_name + and tables.tidb_table_id = ? + and index_id = ? +``` + +## TIDB\_HOT\_REGIONS table + +The `TIDB_HOT_REGIONS` table provides the hot Region information in the current TiKV instance. + +{{< copyable "sql" >}} + +```sql +desc tidb_hot_regions\G +``` + +``` +*************************** 1. row *************************** + Table: TIDB_HOT_REGIONS +Create Table: CREATE TABLE `TIDB_HOT_REGIONS` ( + `TABLE_ID` bigint(21) unsigned DEFAULT NULL, + `INDEX_ID` bigint(21) unsigned DEFAULT NULL, + `DB_NAME` varchar(64) DEFAULT NULL, + `TABLE_NAME` varchar(64) DEFAULT NULL, + `INDEX_NAME` varchar(64) DEFAULT NULL, + `TYPE` varchar(64) DEFAULT NULL, + `MAX_HOT_DEGREE` bigint(21) unsigned DEFAULT NULL, + `REGION_COUNT` bigint(21) unsigned DEFAULT NULL, + `FLOW_BYTES` bigint(21) unsigned DEFAULT NULL +) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin +1 row in set (0.00 sec) +``` + +- `TABLE_ID` and `INDEX_ID` are IDs generated for the corresponding table and index in TiDB. +- `TYPE` is the type for a hot Region. Its value can be `READ` or `WRITE`. + +## TIKV\_STORE\_STATUS table + +The `TIKV_STORE_STATUS` table shows some basic information of TiKV nodes via PD's API, like the ID allocated in the cluster, address and port, and status, capacity, and the number of Region leaders of the current node. + +{{< copyable "sql" >}} + +```sql +desc tikv_store_status\G +``` + +``` +*************************** 1. row *************************** + Table: TIKV_STORE_STATUS +Create Table: CREATE TABLE `TIKV_STORE_STATUS` ( + `STORE_ID` bigint(21) unsigned DEFAULT NULL, + `ADDRESS` varchar(64) DEFAULT NULL, + `STORE_STATE` bigint(21) unsigned DEFAULT NULL, + `STORE_STATE_NAME` varchar(64) DEFAULT NULL, + `LABEL` json unsigned DEFAULT NULL, + `VERSION` varchar(64) DEFAULT NULL, + `CAPACITY` varchar(64) DEFAULT NULL, + `AVAILABLE` varchar(64) DEFAULT NULL, + `LEADER_COUNT` bigint(21) unsigned DEFAULT NULL, + `LEADER_WEIGHT` bigint(21) unsigned DEFAULT NULL, + `LEADER_SCORE` bigint(21) unsigned DEFAULT NULL, + `LEADER_SIZE` bigint(21) unsigned DEFAULT NULL, + `REGION_COUNT` bigint(21) unsigned DEFAULT NULL, + `REGION_WEIGHT` bigint(21) unsigned DEFAULT NULL, + `REGION_SCORE` bigint(21) unsigned DEFAULT NULL, + `REGION_SIZE` bigint(21) unsigned DEFAULT NULL, + `START_TS` datetime unsigned DEFAULT NULL, + `LAST_HEARTBEAT_TS` datetime unsigned DEFAULT NULL, + `UPTIME` varchar(64) DEFAULT NULL +) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin +1 row in set (0.01 sec) +``` + +## TIKV\_REGION\_STATUS table + +The `TIKV_REGION_STATUS` table shows some basic information of TiKV Regions via PD's API, like the Region ID, starting and ending key-values, and read and write traffic. + +{{< copyable "sql" >}} + +```sql +desc tikv_region_status\G +``` + +``` +*************************** 1. row *************************** + Table: TIKV_REGION_STATUS +Create Table: CREATE TABLE `TIKV_REGION_STATUS` ( + `REGION_ID` bigint(21) unsigned DEFAULT NULL, + `START_KEY` text DEFAULT NULL, + `END_KEY` text DEFAULT NULL, + `EPOCH_CONF_VER` bigint(21) unsigned DEFAULT NULL, + `EPOCH_VERSION` bigint(21) unsigned DEFAULT NULL, + `WRITTEN_BYTES` bigint(21) unsigned DEFAULT NULL, + `READ_BYTES` bigint(21) unsigned DEFAULT NULL, + `APPROXIMATE_SIZE` bigint(21) unsigned DEFAULT NULL, + `APPROXIMATE_KEYS` bigint(21) unsigned DEFAULT NULL +) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin +1 row in set (0.00 sec) +``` + +You can implement the `top confver`, `top read` and `top write` operations in pd-ctl via the `ORDER BY X LIMIT Y` operation on the `EPOCH_CONF_VER`, `WRITTEN_BYTES` and `READ_BYTES` columns. + +You can query the top 3 Regions with the most write data using the following SQL statement: + +``` +select * from tikv_region_status order by written_bytes desc limit 3; +``` + +## TIKV\_REGION\_PEERS table + +The `TIKV_REGION_PEERS` table shows detailed information of a single Region node in TiKV, like whether it is a learner or leader. + +{{< copyable "sql" >}} + +```sql +desc tikv_region_peers\G +``` + +``` +*************************** 1. row *************************** + Table: TIKV_REGION_PEERS +Create Table: CREATE TABLE `TIKV_REGION_PEERS` ( + `REGION_ID` bigint(21) unsigned DEFAULT NULL, + `PEER_ID` bigint(21) unsigned DEFAULT NULL, + `STORE_ID` bigint(21) unsigned DEFAULT NULL, + `IS_LEARNER` tinyint(1) unsigned DEFAULT NULL, + `IS_LEADER` tinyint(1) unsigned DEFAULT NULL, + `STATUS` varchar(10) DEFAULT NULL, + `DOWN_SECONDS` bigint(21) unsigned DEFAULT NULL +) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin +1 row in set (0.00 sec) +``` + +For example, you can query the specific TiKV addresses for the top 3 Regions with the maximum value of `WRITTEN_BYTES` using the following SQL statement: + +```sql +select + address, + tikv.address, + region.region_id, +from + tikv_store_status tikv, + tikv_region_peers peer, + ( + select + * + from + tikv_region_status region + order by + written_bytes desc limit 3 + ) + region +where + region.region_id = peer.region_id + and peer.is_leader = 1 + and peer.store_id = tikv.region_id +``` + +## ANALYZE\_STATUS table + +The `ANALYZE_STATUS` table shows the execution status of the `ANALYZE` command in the current cluster. + +{{< copyable "sql" >}} + +```sql +desc analyze_status\G +``` + +``` +*************************** 1. row *************************** + Table: ANALYZE_STATUS +Create Table: CREATE TABLE `ANALYZE_STATUS` ( + `TABLE_SCHEMA` varchar(64) DEFAULT NULL, + `TABLE_NAME` varchar(64) DEFAULT NULL, + `PARTITION_NAME` varchar(64) DEFAULT NULL, + `JOB_INFO` varchar(64) DEFAULT NULL, + `PROCESSED_ROWS` bigint(20) unsigned DEFAULT NULL, + `START_TIME` datetime unsigned DEFAULT NULL, + `STATE` varchar(64) DEFAULT NULL +) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin +1 row in set (0.00 sec) +``` + +The `STATE` column shows the execution status of a specific `ANALYZE` task. Its value can be `pending`, `running`,`finished` or `failed`. + +## SLOW\_QUERY table + +The `SLOW_QUERY` table maps slow query logs. Its column names and field names of slow query logs have an one-to-one corresponse relationship. For details, see [Identify Slow Queries](/identify-slow-queries.md#identify-slow-queries). + +{{< copyable "sql" >}} + +```sql +desc slow_query\G +``` + +``` +*************************** 1. row *************************** + Table: SLOW_QUERY +Create Table: CREATE TABLE `SLOW_QUERY` ( + `Time` timestamp unsigned NULL DEFAULT NULL, + `Txn_start_ts` bigint(20) unsigned DEFAULT NULL, + `User` varchar(64) DEFAULT NULL, + `Host` varchar(64) DEFAULT NULL, + `Conn_ID` bigint(20) unsigned DEFAULT NULL, + `Query_time` double unsigned DEFAULT NULL, + `Process_time` double unsigned DEFAULT NULL, + `Wait_time` double unsigned DEFAULT NULL, + `Backoff_time` double unsigned DEFAULT NULL, + `Request_count` bigint(20) unsigned DEFAULT NULL, + `Total_keys` bigint(20) unsigned DEFAULT NULL, + `Process_keys` bigint(20) unsigned DEFAULT NULL, + `DB` varchar(64) DEFAULT NULL, + `Index_ids` varchar(100) DEFAULT NULL, + `Is_internal` tinyint(1) unsigned DEFAULT NULL, + `Digest` varchar(64) DEFAULT NULL, + `Stats` varchar(512) DEFAULT NULL, + `Cop_proc_avg` double unsigned DEFAULT NULL, + `Cop_proc_p90` double unsigned DEFAULT NULL, + `Cop_proc_max` double unsigned DEFAULT NULL, + `Cop_proc_addr` varchar(64) DEFAULT NULL, + `Cop_wait_avg` double unsigned DEFAULT NULL, + `Cop_wait_p90` double unsigned DEFAULT NULL, + `Cop_wait_max` double unsigned DEFAULT NULL, + `Cop_wait_addr` varchar(64) DEFAULT NULL, + `Mem_max` bigint(20) unsigned DEFAULT NULL, + `Query` varchar(4096) DEFAULT NULL +) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin +1 row in set (0.00 sec) +``` + +## Unsupported Information Schema Tables + +The following `INFORMATION_SCHEMA` tables are present in TiDB, but will always return zero rows: + +* `COLUMN_PRIVILEGES` +* `EVENTS` +* `FILES` +* `GLOBAL_STATUS` +* `GLOBAL_VARIABLES` +* `OPTIMIZER_TRACE` +* `PARAMETERS` +* `PARTITIONS` +* `PLUGINS` +* `PROFILING` +* `REFERENTIAL_CONSTRAINTS` +* `ROUTINES` +* `SCHEMA_PRIVILEGES` +* `SESSION_STATUS` +* `TABLESPACES` +* `TABLE_PRIVILEGES` +* `TRIGGERS` From fdb5e90ec26fd3adfef72f0ea2a20cab50f74cd9 Mon Sep 17 00:00:00 2001 From: Ran Date: Fri, 17 Jul 2020 18:18:57 +0800 Subject: [PATCH 2/8] align with #3678 Signed-off-by: Ran --- .../system-table-information-schema.md | 42 +++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md index 81ccfffa92b88..399b0a4956589 100644 --- a/system-tables/system-table-information-schema.md +++ b/system-tables/system-table-information-schema.md @@ -416,6 +416,11 @@ SELECT * FROM session_variables LIMIT 10; 10 rows in set (0.00 sec) ``` +The description of columns in the `SESSION_VARIABLES` table is as follows: + +* `VARIABLE_NAME`: The name of the session-level variable in the database. +* `VARIABLE_VALUE`: The value of the session-level variable in the database. + ## SLOW_QUERY table The `SLOW_QUERY` table provides the slow query information of the current node, which is the parsing result of the TiDB slow log file. The column names in the table are corresponding to the field names in the slow log. For how to use this table to identify problematic statements and improve query performance, see [Slow Query Log Document](/identify-slow-queries.md). @@ -672,6 +677,30 @@ SHOW TABLES [LIKE 'wild'] ``` +The description of columns in the `TABLES` table is as follows: + +* `TABLE_CATALOG`: The name of the catalog which the table belongs to. The value is always `def`. +* `TABLE_SCHEMA`: The name of the schema which the table belongs to. +* `TABLE_NAME`: The name of the table. +* `TABLE_TYPE`: The type of the table. +* `ENGINE`: The type of the storage engine. The value is currently `InnoDB`. +* `VERSION`: Version. The value is `10` by default. +* `ROW_FORMAT`: The row format. The value is currently `Compact`. +* `TABLE_ROWS`: The number of rows in the table in statistics. +* `AVG_ROW_LENGTH`: The average row length of the table. `AVG_ROW_LENGTH` = `DATA_LENGTH` / `TABLE_ROWS`. +* `DATA_LENGTH`: Data length. `DATA_LENGTH` = `TABLE_ROWS` * the sum of storage lengths of the columns in the tuple. The replicas of TiKV is not taken into account. +* `MAX_DATA_LENGTH`: The maximum data length. The value is currently `0`, which means the data length has no upper limit. +* `INDEX_LENGTH`: The index length. `INDEX_LENGTH` = `TABLE_ROWS` * the sum of lengths of the columns in the index tuple. The replicas of TiKV is not taken into account. +* `DATA_FREE`: Data fragment. The value is currently `0`. +* `AUTO_INCREMENT`: The current step of the auto-increment primary key. +* `CREATE_TIME`: The time at which the table is created. +* `UPDATE_TIME`: The time at which the table is updated. +* `CHECK_TIME`: The time at which the table is checked. +* `TABLE_COLLATION`: The character check code set of the table. +* `CHECKSUM`: Checksum. +* `CREATE_OPTIONS`: Create options. +* `TABLE_COMMENT`: The comments and notes of the table. + Most of the information in the table is the same as MySQL. Only two columns are newly defined by TiDB: * `TIDB_TABLE_ID`: to indicate the internal ID of a table. This ID is unique in a TiDB cluster. @@ -767,6 +796,19 @@ desc TIDB_HOT_REGIONS; +----------------+---------------------+------+-----+---------+-------+ ``` +The description of columns in the `TIDB_HOT_REGIONS` table is as follows: + +* `TABLE_ID`: ID of the table which the hot Region is located. +* `INDEX_ID`: ID of the index which the hot Region is located. +* `DB_NAME`: The database name of the object which the hot Region is located. +* `TABLE_NAME`: The name of the table which the hot Region is located. +* `INDEX_NAME`: The name of the index which the hot Region is located. +* `REGION_ID`: ID of the hot Region. +* `TYPE`: The type of the hot Region. +* `MAX_HOT_DEGREE`: The maximum hot degree of the Region. +* `REGION_COUNT`: The number of Regions in the instance. +* `FLOW_BYTES`: The number of bytes written and read in the Region. + ### TIDB_INDEXES table The `TIDB_INDEXES` table provides the INDEX information of all tables. From 2a8f301dab9b15077f25de35980582d0f3e67685 Mon Sep 17 00:00:00 2001 From: Ran Date: Fri, 17 Jul 2020 18:29:48 +0800 Subject: [PATCH 3/8] update an expression --- system-tables/system-table-information-schema.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md index 399b0a4956589..dcd2d03da83ad 100644 --- a/system-tables/system-table-information-schema.md +++ b/system-tables/system-table-information-schema.md @@ -696,7 +696,7 @@ The description of columns in the `TABLES` table is as follows: * `CREATE_TIME`: The time at which the table is created. * `UPDATE_TIME`: The time at which the table is updated. * `CHECK_TIME`: The time at which the table is checked. -* `TABLE_COLLATION`: The character check code set of the table. +* `TABLE_COLLATION`: Table collation (to compare string). * `CHECKSUM`: Checksum. * `CREATE_OPTIONS`: Create options. * `TABLE_COMMENT`: The comments and notes of the table. From 6e73744e2881ef733f84be0837fa89aeecf5e882 Mon Sep 17 00:00:00 2001 From: Ran Date: Fri, 17 Jul 2020 18:38:55 +0800 Subject: [PATCH 4/8] update an expression again --- system-tables/system-table-information-schema.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md index dcd2d03da83ad..cae4e850567c8 100644 --- a/system-tables/system-table-information-schema.md +++ b/system-tables/system-table-information-schema.md @@ -696,7 +696,7 @@ The description of columns in the `TABLES` table is as follows: * `CREATE_TIME`: The time at which the table is created. * `UPDATE_TIME`: The time at which the table is updated. * `CHECK_TIME`: The time at which the table is checked. -* `TABLE_COLLATION`: Table collation (to compare string). +* `TABLE_COLLATION`: The collation of strings in the table. * `CHECKSUM`: Checksum. * `CREATE_OPTIONS`: Create options. * `TABLE_COMMENT`: The comments and notes of the table. From a0d310b862ff6717d01003eab39fc551b9a50915 Mon Sep 17 00:00:00 2001 From: Ran Date: Tue, 21 Jul 2020 15:22:22 +0800 Subject: [PATCH 5/8] Apply suggestions from code review Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com> --- system-tables/system-table-information-schema.md | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md index cae4e850567c8..4973a1fd663ab 100644 --- a/system-tables/system-table-information-schema.md +++ b/system-tables/system-table-information-schema.md @@ -61,7 +61,7 @@ The description of columns in the `CHARACTER_SETS` table is as follows: * `CHARACTER_SET_NAME`: The name of the character set. * `DEFAULT_COLLATE_NAME`：The default collation name of the character set. -* `DESCRIPTION`：The description of the character set +* `DESCRIPTION`：The description of the character set. * `MAXLEN`：The maximum length required to store a character in this character set. ### COLLATIONS table @@ -688,9 +688,9 @@ The description of columns in the `TABLES` table is as follows: * `ROW_FORMAT`: The row format. The value is currently `Compact`. * `TABLE_ROWS`: The number of rows in the table in statistics. * `AVG_ROW_LENGTH`: The average row length of the table. `AVG_ROW_LENGTH` = `DATA_LENGTH` / `TABLE_ROWS`. -* `DATA_LENGTH`: Data length. `DATA_LENGTH` = `TABLE_ROWS` * the sum of storage lengths of the columns in the tuple. The replicas of TiKV is not taken into account. +* `DATA_LENGTH`: Data length. `DATA_LENGTH` = `TABLE_ROWS` \* the sum of storage lengths of the columns in the tuple. The replicas of TiKV are not taken into account. * `MAX_DATA_LENGTH`: The maximum data length. The value is currently `0`, which means the data length has no upper limit. -* `INDEX_LENGTH`: The index length. `INDEX_LENGTH` = `TABLE_ROWS` * the sum of lengths of the columns in the index tuple. The replicas of TiKV is not taken into account. +* `INDEX_LENGTH`: The index length. `INDEX_LENGTH` = `TABLE_ROWS` \* the sum of lengths of the columns in the index tuple. The replicas of TiKV are not taken into account. * `DATA_FREE`: Data fragment. The value is currently `0`. * `AUTO_INCREMENT`: The current step of the auto-increment primary key. * `CREATE_TIME`: The time at which the table is created. @@ -698,7 +698,7 @@ The description of columns in the `TABLES` table is as follows: * `CHECK_TIME`: The time at which the table is checked. * `TABLE_COLLATION`: The collation of strings in the table. * `CHECKSUM`: Checksum. -* `CREATE_OPTIONS`: Create options. +* `CREATE_OPTIONS`: Creates options. * `TABLE_COMMENT`: The comments and notes of the table. Most of the information in the table is the same as MySQL. Only two columns are newly defined by TiDB: @@ -798,9 +798,9 @@ desc TIDB_HOT_REGIONS; The description of columns in the `TIDB_HOT_REGIONS` table is as follows: -* `TABLE_ID`: ID of the table which the hot Region is located. -* `INDEX_ID`: ID of the index which the hot Region is located. -* `DB_NAME`: The database name of the object which the hot Region is located. +* `TABLE_ID`: ID of the table in which the hot Region is located. +* `INDEX_ID`: ID of the index in which the hot Region is located. +* `DB_NAME`: The database name of the object in which the hot Region is located. * `TABLE_NAME`: The name of the table which the hot Region is located. * `INDEX_NAME`: The name of the index which the hot Region is located. * `REGION_ID`: ID of the hot Region. From f6ee628d4660af94699097576294db7ffdac94e4 Mon Sep 17 00:00:00 2001 From: Ran Date: Tue, 21 Jul 2020 15:22:51 +0800 Subject: [PATCH 6/8] Apply suggestions from code review --- system-tables/system-table-information-schema.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md index 4973a1fd663ab..1eb31919fed7c 100644 --- a/system-tables/system-table-information-schema.md +++ b/system-tables/system-table-information-schema.md @@ -801,8 +801,8 @@ The description of columns in the `TIDB_HOT_REGIONS` table is as follows: * `TABLE_ID`: ID of the table in which the hot Region is located. * `INDEX_ID`: ID of the index in which the hot Region is located. * `DB_NAME`: The database name of the object in which the hot Region is located. -* `TABLE_NAME`: The name of the table which the hot Region is located. -* `INDEX_NAME`: The name of the index which the hot Region is located. +* `TABLE_NAME`: The name of the table in which the hot Region is located. +* `INDEX_NAME`: The name of the index in which the hot Region is located. * `REGION_ID`: ID of the hot Region. * `TYPE`: The type of the hot Region. * `MAX_HOT_DEGREE`: The maximum hot degree of the Region. From 595a774381571985e14ef619bc79fa155170c23c Mon Sep 17 00:00:00 2001 From: Ran Date: Tue, 21 Jul 2020 16:10:30 +0800 Subject: [PATCH 7/8] resolve conflicts Signed-off-by: Ran --- ...a-collation-character-set-applicability.md | 10 + .../information-schema-collations.md | 14 + .../information-schema-session-variables.md | 8 +- .../information-schema-tables.md | 24 + .../information-schema-tidb-hot-regions.md | 14 +- .../system-table-information-schema.md | 1269 ----------------- 6 files changed, 67 insertions(+), 1272 deletions(-) delete mode 100644 system-tables/system-table-information-schema.md diff --git a/information-schema/information-schema-collation-character-set-applicability.md b/information-schema/information-schema-collation-character-set-applicability.md index 67ee8ac0ae684..1bc8238b9f1e0 100644 --- a/information-schema/information-schema-collation-character-set-applicability.md +++ b/information-schema/information-schema-collation-character-set-applicability.md @@ -38,3 +38,13 @@ SELECT * FROM collation_character_set_applicability WHERE character_set_name='ut +----------------+--------------------+ 1 row in set (0.00 sec) ``` + ++----------------+--------------------+ +| COLLATION_NAME | CHARACTER_SET_NAME | +| utf8mb4_bin | utf8mb4 | ++----------------+--------------------+ + +The description of columns in the `COLLATION_CHARACTER_SET_APPLICABILITY` table is as follows: + +* `COLLATION_NAME`: The name of the collation. +* `CHARACTER_SET_NAME`: The name of the character set which the collation belongs to. diff --git a/information-schema/information-schema-collations.md b/information-schema/information-schema-collations.md index 5196b77c49090..1b3dec5ecc476 100644 --- a/information-schema/information-schema-collations.md +++ b/information-schema/information-schema-collations.md @@ -42,3 +42,17 @@ SELECT * FROM collations WHERE character_set_name='utf8mb4'; +----------------+--------------------+------+------------+-------------+---------+ 1 row in set (0.00 sec) ``` + +The description of columns in the `COLLATION` table is +as follows: + +* `COLLATION_NAME`: The name of the collation. +* `CHARACTER_SET_NAME`: The name of the character set +which the collation belongs to. +* `ID`: The ID of the collation. +* `IS_DEFAULT`: Whether this collation is the default +collation of the character set it belongs to. +* `IS_COMPILED`: Whether the character set is compiled +into the server. +* `SORTLEN`: The minimum length of memory allocated when +the collation sorts characters. diff --git a/information-schema/information-schema-session-variables.md b/information-schema/information-schema-session-variables.md index bc8a786696b20..04460c8838e7c 100644 --- a/information-schema/information-schema-session-variables.md +++ b/information-schema/information-schema-session-variables.md @@ -46,4 +46,10 @@ SELECT * FROM session_variables ORDER BY variable_name LIMIT 10; | bind_address | * | +-----------------------------------+------------------+ 10 rows in set (0.00 sec) -``` \ No newline at end of file +``` + +The description of columns in the `SESSION_VARIABLES` table is as follows: + +* `VARIABLE_NAME`: The name of the session-level variable in the database. +* `VARIABLE_VALUE`: The value of the session-level +variable in the database. diff --git a/information-schema/information-schema-tables.md b/information-schema/information-schema-tables.md index 28dca095253fe..616be7fde1115 100644 --- a/information-schema/information-schema-tables.md +++ b/information-schema/information-schema-tables.md @@ -91,6 +91,30 @@ SHOW TABLES [LIKE 'wild'] ``` +The description of columns in the `TABLES` table is as follows: + +* `TABLE_CATALOG`: The name of the catalog which the table belongs to. The value is always `def`. +* `TABLE_SCHEMA`: The name of the schema which the table belongs to. +* `TABLE_NAME`: The name of the table. +* `TABLE_TYPE`: The type of the table. +* `ENGINE`: The type of the storage engine. The value is currently `InnoDB`. +* `VERSION`: Version. The value is `10` by default. +* `ROW_FORMAT`: The row format. The value is currently `Compact`. +* `TABLE_ROWS`: The number of rows in the table in statistics. +* `AVG_ROW_LENGTH`: The average row length of the table. `AVG_ROW_LENGTH` = `DATA_LENGTH` / `TABLE_ROWS`. +* `DATA_LENGTH`: Data length. `DATA_LENGTH` = `TABLE_ROWS` \* the sum of storage lengths of the columns in the tuple. The replicas of TiKV are not taken into account. +* `MAX_DATA_LENGTH`: The maximum data length. The value is currently `0`, which means the data length has no upper limit. +* `INDEX_LENGTH`: The index length. `INDEX_LENGTH` = `TABLE_ROWS` \* the sum of lengths of the columns in the index tuple. The replicas of TiKV are not taken into account. +* `DATA_FREE`: Data fragment. The value is currently `0`. +* `AUTO_INCREMENT`: The current step of the auto- increment primary key. +* `CREATE_TIME`: The time at which the table is created. +* `UPDATE_TIME`: The time at which the table is updated. +* `CHECK_TIME`: The time at which the table is checked. +* `TABLE_COLLATION`: The collation of strings in the table. +* `CHECKSUM`: Checksum. +* `CREATE_OPTIONS`: Creates options. +* `TABLE_COMMENT`: The comments and notes of the table. + Most of the information in the table is the same as MySQL. Only two columns are newly defined by TiDB: * `TIDB_TABLE_ID`: to indicate the internal ID of a table. This ID is unique in a TiDB cluster. diff --git a/information-schema/information-schema-tidb-hot-regions.md b/information-schema/information-schema-tidb-hot-regions.md index 98ead5d7daa1b..7ced317f88518 100644 --- a/information-schema/information-schema-tidb-hot-regions.md +++ b/information-schema/information-schema-tidb-hot-regions.md @@ -32,5 +32,15 @@ DESC tidb_hot_regions; 10 rows in set (0.00 sec) ``` -- `TABLE_ID` and `INDEX_ID` are IDs generated for the corresponding table and index in TiDB. -- `TYPE` is the type for a hot Region. Its value can be `READ` or `WRITE`. \ No newline at end of file +The description of columns in the `TIDB_HOT_REGIONS` table is as follows: + +* `TABLE_ID`: ID of located. +* `INDEX_ID`: ID of the table in which the hot Region is the index in which the hot Region is located. +* `DB_NAME`: The database name of the object in which the hot Region is located. +* `TABLE_NAME`: The name of the table in which the hot Region is located. +* `INDEX_NAME`: The name of the index in which the hot Region is located. +* `REGION_ID`: ID of the hot Region. +* `TYPE`: The type of the hot Region. +* `MAX_HOT_DEGREE`: The maximum hot degree of the Region. +* `REGION_COUNT`: The number of Regions in the instance. +* `FLOW_BYTES`: The number of bytes written and read in the Region. diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md deleted file mode 100644 index 1eb31919fed7c..0000000000000 --- a/system-tables/system-table-information-schema.md +++ /dev/null @@ -1,1269 +0,0 @@ ---- -title: Information Schema -summary: Learn how to use Information Schema in TiDB. -aliases: ['/docs/dev/system-tables/system-table-information-schema/','/docs/dev/reference/system-databases/information-schema/'] ---- - -# Information Schema - -As part of MySQL compatibility, TiDB supports a number of `INFORMATION_SCHEMA` tables. Many of these tables also have a corresponding `SHOW` command. The benefit of querying `INFORMATION_SCHEMA` is that it is possible to join between tables. - -## Fully Supported Information Schema Tables - -### ANALYZE_STATUS table - -The `ANALYZE_STATUS` table provides information about the running tasks that collect statistics and a limited number of history tasks. - -{{< copyable "sql" >}} - -```sql -select * from `ANALYZE_STATUS`; -``` - -``` -+--------------+------------+----------------+-------------------+----------------+---------------------+----------+ -| TABLE_SCHEMA | TABLE_NAME | PARTITION_NAME | JOB_INFO | PROCESSED_ROWS | START_TIME | STATE | -+--------------+------------+----------------+-------------------+----------------+---------------------+----------+ -| test | t | | analyze index idx | 2 | 2019-06-21 19:51:14 | finished | -| test | t | | analyze columns | 2 | 2019-06-21 19:51:14 | finished | -| test | t1 | p0 | analyze columns | 0 | 2019-06-21 19:51:15 | finished | -| test | t1 | p3 | analyze columns | 0 | 2019-06-21 19:51:15 | finished | -| test | t1 | p1 | analyze columns | 0 | 2019-06-21 19:51:15 | finished | -| test | t1 | p2 | analyze columns | 1 | 2019-06-21 19:51:15 | finished | -+--------------+------------+----------------+-------------------+----------------+---------------------+----------+ -6 rows in set -``` - -### CHARACTER_SETS table - -The `CHARACTER_SETS` table provides information about [character sets](/character-set-and-collation.md). Currently, TiDB only supports some of the character sets. - -{{< copyable "sql" >}} - -```sql -SELECT * FROM character_sets; -``` - -``` -+--------------------+----------------------+---------------+--------+ -| CHARACTER_SET_NAME | DEFAULT_COLLATE_NAME | DESCRIPTION | MAXLEN | -+--------------------+----------------------+---------------+--------+ -| utf8 | utf8_bin | UTF-8 Unicode | 3 | -| utf8mb4 | utf8mb4_bin | UTF-8 Unicode | 4 | -| ascii | ascii_bin | US ASCII | 1 | -| latin1 | latin1_bin | Latin1 | 1 | -| binary | binary | binary | 1 | -+--------------------+----------------------+---------------+--------+ -5 rows in set (0.00 sec) -``` - -The description of columns in the `CHARACTER_SETS` table is as follows: - -* `CHARACTER_SET_NAME`: The name of the character set. -* `DEFAULT_COLLATE_NAME`：The default collation name of the character set. -* `DESCRIPTION`：The description of the character set. -* `MAXLEN`：The maximum length required to store a character in this character set. - -### COLLATIONS table - -The `COLLATIONS` table provides a list of collations that correspond to character sets in the `CHARACTER_SETS` table. Currently this table is included only for compatibility with MySQL, as TiDB only supports binary collation: - -{{< copyable "sql" >}} - -```sql -SELECT * FROM collations WHERE character_set_name='utf8mb4'; -``` - -``` -+------------------------+--------------------+------+------------+-------------+---------+ -| COLLATION_NAME | CHARACTER_SET_NAME | ID | IS_DEFAULT | IS_COMPILED | SORTLEN | -+------------------------+--------------------+------+------------+-------------+---------+ -| utf8mb4_general_ci | utf8mb4 | 45 | Yes | Yes | 1 | -| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 | -| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 | -| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 1 | -| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 1 | -| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 1 | -| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 1 | -| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 1 | -| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 1 | -| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 1 | -| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 1 | -| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 1 | -| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 1 | -| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 1 | -| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 1 | -| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 1 | -| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 1 | -| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 1 | -| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 1 | -| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 1 | -| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 1 | -| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 1 | -| utf8mb4_german2_ci | utf8mb4 | 244 | | Yes | 1 | -| utf8mb4_croatian_ci | utf8mb4 | 245 | | Yes | 1 | -| utf8mb4_unicode_520_ci | utf8mb4 | 246 | | Yes | 1 | -| utf8mb4_vietnamese_ci | utf8mb4 | 247 | | Yes | 1 | -+------------------------+--------------------+------+------------+-------------+---------+ -26 rows in set (0.00 sec) -``` - -The description of columns in the `COLLATION` table is as follows: - -* `COLLATION_NAME`: The name of the collation. -* `CHARACTER_SET_NAME`: The name of the character set which the collation belongs to. -* `ID`: The ID of the collation. -* `IS_DEFAULT`: Whether this collation is the default collation of the character set it belongs to. -* `IS_COMPILED`: Whether the character set is compiled into the server. -* `SORTLEN`: The minimum length of memory allocated when the collation sorts characters. - -### COLLATION_CHARACTER_SET_APPLICABILITY table - -The `COLLATION_CHARACTER_SET_APPLICABILITY` table maps collations to the applicable character set name. Similar to the `COLLATIONS` table, it is included only for compatibility with MySQL: - -{{< copyable "sql" >}} - -```sql -SELECT * FROM collation_character_set_applicability WHERE character_set_name='utf8mb4'; -``` - -+----------------+--------------------+ -| COLLATION_NAME | CHARACTER_SET_NAME | -+----------------+--------------------+ -| utf8mb4_bin | utf8mb4 | -+----------------+--------------------+ - -The description of columns in the `COLLATION_CHARACTER_SET_APPLICABILITY` table is as follows: - -* `COLLATION_NAME`: The name of the collation. -* `CHARACTER_SET_NAME`: The name of the character set which the collation belongs to. - -### COLUMNS table - -The `COLUMNS` table provides detailed information about columns in tables: - -{{< copyable "sql" >}} - -```sql -CREATE TABLE test.t1 (a int); -``` - -``` -1 row in set (0.01 sec) -``` - -{{< copyable "sql" >}} - -```sql -SELECT * FROM information_schema.columns WHERE table_schema='test' AND TABLE_NAME='t1'; -``` - -``` -*************************** 1. row *************************** - TABLE_CATALOG: def - TABLE_SCHEMA: test - TABLE_NAME: t1 - COLUMN_NAME: a - ORDINAL_POSITION: 1 - COLUMN_DEFAULT: NULL - IS_NULLABLE: YES - DATA_TYPE: int -CHARACTER_MAXIMUM_LENGTH: NULL - CHARACTER_OCTET_LENGTH: NULL - NUMERIC_PRECISION: 11 - NUMERIC_SCALE: 0 - DATETIME_PRECISION: NULL - CHARACTER_SET_NAME: NULL - COLLATION_NAME: NULL - COLUMN_TYPE: int(11) - COLUMN_KEY: - EXTRA: - PRIVILEGES: select,insert,update,references - COLUMN_COMMENT: - GENERATION_EXPRESSION: -1 row in set (0.01 sec) -``` - -The description of columns in the `COLUMNS` table is as follows: - -* `TABLE_CATALOG`: The name of the catalog to which the table with the column belongs. The value is always `def`. -* `TABLE_SCHEMA`: The name of the schema in which the table with the column is located. -* `TABLE_NAME`: The name of the table with the column. -* `COLUMN_NAME`: The name of the column. -* `ORDINAL_POSITION`: The position of the column in the table. -* `COLUMN_DEFAULT`: The default value of the column. If the explicit default value is `NULL`, or if the column definition does not include the `default` clause, this value is `NULL`. -* `IS_NULLABLE`: Whether the column is nullable. If the column can store null values, this value is `YES`; otherwise, it is `NO`. -* `DATA_TYPE`: The type of data in the column. -* `CHARACTER_MAXIMUM_LENGTH`: For string columns, the maximum length in characters. -* `CHARACTER_OCTET_LENGTH`: For string columns, the maximum length in bytes. -* `NUMERIC_PRECISION`: The numeric precision of a number-type column. -* `NUMERIC_SCALE`: The numeric scale of a number-type column. -* `DATETIME_PRECISION`: For time-type columns, the fractional seconds precision. -* `CHARACTER_SET_NAME`: The name of the character set of a string column. -* `COLLATION_NAME`: The name of the collation of a string column. -* `COLUMN_TYPE`: The column type. -* `COLUMN_KEY`: Whether this column is indexed. This field might have the following values: - * Empty: This column is not indexed, or this column is indexed and is the second column in a multi-column non-unique index. - * `PRI`: This column is the primary key or one of multiple primary keys. - * `UNI`: This column is the first column of the unique index. - * `MUL`: The column is the first column of a non-unique index, in which a given value is allowed to occur for multiple times. -* `EXTRA`: Any additional information of the given column. -* `PRIVILEGES`: The privilege that the current user has on this column. Currently, this value is fixed in TiDB, and is always `select,insert,update,references`. -* `COLUMN_COMMENT`: Comments contained in the column definition. -* `GENERATION_EXPRESSION`: For generated columns, this value displays the expression used to calculate the column value. For non-generated columns, the value is empty. - -The corresponding `SHOW` statement is as follows: - -{{< copyable "sql" >}} - -```sql -SHOW COLUMNS FROM t1 FROM test; -``` - -``` -+-------+---------+------+------+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+-------+---------+------+------+---------+-------+ -| a | int(11) | YES | | NULL | | -+-------+---------+------+------+---------+-------+ -1 row in set (0.00 sec) -``` - -### ENGINES table - -The `ENGINES` table provides information about storage engines. For compatibility, TiDB will always describe InnoDB as the only supported engine. In addition, other column values in the `ENGINES` table are also fixed values. - -{{< copyable "sql" >}} - -```sql -SELECT * FROM engines; -``` - -``` -*************************** 1. row *************************** - ENGINE: InnoDB - SUPPORT: DEFAULT - COMMENT: Supports transactions, row-level locking, and foreign keys -TRANSACTIONS: YES - XA: YES - SAVEPOINTS: YES -1 row in set (0.00 sec) -``` - -The description of columns in the `ENGINES` table is as follows: - -* `ENGINES`: The name of the storage engine. -* `SUPPORT`: The level of support that the server has on the storage engine. In TiDB, the value is always `DEFAULT`. -* `COMMENT`: The brief comment on the storage engine. -* `TRANSACTIONS`：Whether the storage engine supports transactions. -* `XA`: Whether the storage engine supports XA transactions. -* `SAVEPOINTS`: Whether the storage engine supports `savepoints`. - -### KEY_COLUMN_USAGE table - -The `KEY_COLUMN_USAGE` table describes the key constraints of the columns, such as the primary key constraint: - -{{< copyable "sql" >}} - -```sql -SELECT * FROM key_column_usage WHERE table_schema='mysql' and table_name='user'; -``` - -``` -*************************** 1. row *************************** - CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: PRIMARY - TABLE_CATALOG: def - TABLE_SCHEMA: mysql - TABLE_NAME: user - COLUMN_NAME: Host - ORDINAL_POSITION: 1 -POSITION_IN_UNIQUE_CONSTRAINT: NULL - REFERENCED_TABLE_SCHEMA: NULL - REFERENCED_TABLE_NAME: NULL - REFERENCED_COLUMN_NAME: NULL -*************************** 2. row *************************** - CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: PRIMARY - TABLE_CATALOG: def - TABLE_SCHEMA: mysql - TABLE_NAME: user - COLUMN_NAME: User - ORDINAL_POSITION: 2 -POSITION_IN_UNIQUE_CONSTRAINT: NULL - REFERENCED_TABLE_SCHEMA: NULL - REFERENCED_TABLE_NAME: NULL - REFERENCED_COLUMN_NAME: NULL -2 rows in set (0.00 sec) -``` - -The description of columns in the `KEY_COLUMN_USAGE` table is as follows: - -* `CONSTRAINT_CATALOG`: The name of the catalog to which the constraint belongs. The value is always `def`. -* `CONSTRAINT_SCHEMA`: The name of the schema to which the constraint belongs. -* `CONSTRAINT_NAME`: The name of the constraint. -* `TABLE_CATALOG`: The name of the catalog to which the table belongs. The value is always `def`. -* `TABLE_SCHEMA`: The name of the schema to which the table belongs. -* `TABLE_NAME`: The name of the table with constraints. -* `COLUMN_NAME`: The name of the column with constraints. -* `ORDINAL_POSITION`: The position of the column in the constraint, rather than in the table. The position number starts from `1`. -* `POSITION_IN_UNIQUE_CONSTRAINT`: The unique constraint and the primary key constraint are empty. For foreign key constraints, this column is the position of the referenced table's key. -* `REFERENCED_TABLE_SCHEMA`: The name of the schema referenced by the constraint. Currently in TiDB, the value of this column in all constraints is `nil`, except for the foreign key constraint. -* `REFERENCED_TABLE_NAME`: The name of the table referenced by the constraint. Currently in TiDB, the value of this column in all constraints is `nil`, except for the foreign key constraint. -* `REFERENCED_COLUMN_NAME`: The name of the column referenced by the constraint. Currently in TiDB, the value of this column in all constraints is `nil`, except for the foreign key constraint. - -### PROCESSLIST table - -`PROCESSLIST`, just like `show processlist`, is used to view the requests that are being handled. - -The `PROCESSLIST` table has a `MEM` column that `show processlist` does not have. `MEM` means the occupied memory of the requests being handled, and its unit is `byte`. - -``` -+----+------+------+--------------------+---------+------+-------+---------------------------+-----+ -| ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | MEM | -+----+------+------+--------------------+---------+------+-------+---------------------------+-----+ -| 1 | root | ::1 | INFORMATION_SCHEMA | Query | 0 | 2 | select * from PROCESSLIST | 0 | -+----+------+------+--------------------+---------+------+-------+---------------------------+-----+ -``` - -### SCHEMATA table - -The `SCHEMATA` table provides information about databases. The table data is equivalent to the result of the `SHOW DATABASES` statement: - -{{< copyable "sql" >}} - -```sql -select * from SCHEMATA; -``` - -``` -*************************** 1. row *************************** - CATALOG_NAME: def - SCHEMA_NAME: INFORMATION_SCHEMA -DEFAULT_CHARACTER_SET_NAME: utf8mb4 - DEFAULT_COLLATION_NAME: utf8mb4_bin - SQL_PATH: NULL -*************************** 2. row *************************** - CATALOG_NAME: def - SCHEMA_NAME: mysql -DEFAULT_CHARACTER_SET_NAME: utf8mb4 - DEFAULT_COLLATION_NAME: utf8mb4_bin - SQL_PATH: NULL -*************************** 3. row *************************** - CATALOG_NAME: def - SCHEMA_NAME: PERFORMANCE_SCHEMA -DEFAULT_CHARACTER_SET_NAME: utf8mb4 - DEFAULT_COLLATION_NAME: utf8mb4_bin - SQL_PATH: NULL -*************************** 4. row *************************** - CATALOG_NAME: def - SCHEMA_NAME: test -DEFAULT_CHARACTER_SET_NAME: utf8mb4 - DEFAULT_COLLATION_NAME: utf8mb4_bin - SQL_PATH: NULL -4 rows in set (0.00 sec) -``` - -## CLUSTER_PROCESSLIST - -`CLUSTER_PROCESSLIST` is the cluster system table corresponding to `PROCESSLIST`. It is used to query the `PROCESSLIST` information of all TiDB nodes in the cluster. The table schema of `CLUSTER_PROCESSLIST` has one more column than `PROCESSLIST`, the `INSTANCE` column, which stores the address of the TiDB node this row of data is from. - -{{< copyable "sql" >}} - -```sql -SELECT * FROM information_schema.cluster_processlist; -``` - -``` -+-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ -| INSTANCE | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | MEM | TxnStart | -+-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ -| 10.0.1.22:10080 | 150 | u1 | 10.0.1.1 | test | Query | 0 | autocommit | select count(*) from usertable | 372 | 05-28 03:54:21.230(416976223923077223) | -| 10.0.1.22:10080 | 138 | root | 10.0.1.1 | test | Query | 0 | autocommit | SELECT * FROM information_schema.cluster_processlist | 0 | 05-28 03:54:21.230(416976223923077220) | -| 10.0.1.22:10080 | 151 | u1 | 10.0.1.1 | test | Query | 0 | autocommit | select count(*) from usertable | 372 | 05-28 03:54:21.230(416976223923077224) | -| 10.0.1.21:10080 | 15 | u2 | 10.0.1.1 | test | Query | 0 | autocommit | select max(field0) from usertable | 496 | 05-28 03:54:21.230(416976223923077222) | -| 10.0.1.21:10080 | 14 | u2 | 10.0.1.1 | test | Query | 0 | autocommit | select max(field0) from usertable | 496 | 05-28 03:54:21.230(416976223923077225) | -+-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ -``` - -### SESSION_VARIABLES table - -The `SESSION_VARIABLES` table provides information about session variables. The table data is similar to the result of the `SHOW SESSION VARIABLES` statement: - -{{< copyable "sql" >}} - -```sql -SELECT * FROM session_variables LIMIT 10; -``` - -``` -+----------------------------------+----------------------+ -| VARIABLE_NAME | VARIABLE_VALUE | -+----------------------------------+----------------------+ -| max_write_lock_count | 18446744073709551615 | -| server_id_bits | 32 | -| net_read_timeout | 30 | -| innodb_online_alter_log_max_size | 134217728 | -| innodb_optimize_fulltext_only | OFF | -| max_join_size | 18446744073709551615 | -| innodb_read_io_threads | 4 | -| session_track_gtids | OFF | -| have_ssl | DISABLED | -| max_binlog_cache_size | 18446744073709547520 | -+----------------------------------+----------------------+ -10 rows in set (0.00 sec) -``` - -The description of columns in the `SESSION_VARIABLES` table is as follows: - -* `VARIABLE_NAME`: The name of the session-level variable in the database. -* `VARIABLE_VALUE`: The value of the session-level variable in the database. - -## SLOW_QUERY table - -The `SLOW_QUERY` table provides the slow query information of the current node, which is the parsing result of the TiDB slow log file. The column names in the table are corresponding to the field names in the slow log. For how to use this table to identify problematic statements and improve query performance, see [Slow Query Log Document](/identify-slow-queries.md). - -{{< copyable "sql" >}} - -```sql -desc information_schema.slow_query; -``` - -```sql -+---------------------------+---------------------+------+-----+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+---------------------------+---------------------+------+-----+---------+-------+ -| Time | timestamp unsigned | YES | | | | -| Txn_start_ts | bigint(20) unsigned | YES | | | | -| User | varchar(64) | YES | | | | -| Host | varchar(64) | YES | | | | -| Conn_ID | bigint(20) unsigned | YES | | | | -| Query_time | double unsigned | YES | | | | -| Parse_time | double unsigned | YES | | | | -| Compile_time | double unsigned | YES | | | | -| Prewrite_time | double unsigned | YES | | | | -| Wait_prewrite_binlog_time | double unsigned | YES | | | | -| Commit_time | double unsigned | YES | | | | -| Get_commit_ts_time | double unsigned | YES | | | | -| Commit_backoff_time | double unsigned | YES | | | | -| Backoff_types | varchar(64) | YES | | | | -| Resolve_lock_time | double unsigned | YES | | | | -| Local_latch_wait_time | double unsigned | YES | | | | -| Write_keys | bigint(22) unsigned | YES | | | | -| Write_size | bigint(22) unsigned | YES | | | | -| Prewrite_region | bigint(22) unsigned | YES | | | | -| Txn_retry | bigint(22) unsigned | YES | | | | -| Process_time | double unsigned | YES | | | | -| Wait_time | double unsigned | YES | | | | -| Backoff_time | double unsigned | YES | | | | -| LockKeys_time | double unsigned | YES | | | | -| Request_count | bigint(20) unsigned | YES | | | | -| Total_keys | bigint(20) unsigned | YES | | | | -| Process_keys | bigint(20) unsigned | YES | | | | -| DB | varchar(64) | YES | | | | -| Index_names | varchar(100) | YES | | | | -| Is_internal | tinyint(1) unsigned | YES | | | | -| Digest | varchar(64) | YES | | | | -| Stats | varchar(512) | YES | | | | -| Cop_proc_avg | double unsigned | YES | | | | -| Cop_proc_p90 | double unsigned | YES | | | | -| Cop_proc_max | double unsigned | YES | | | | -| Cop_proc_addr | varchar(64) | YES | | | | -| Cop_wait_avg | double unsigned | YES | | | | -| Cop_wait_p90 | double unsigned | YES | | | | -| Cop_wait_max | double unsigned | YES | | | | -| Cop_wait_addr | varchar(64) | YES | | | | -| Mem_max | bigint(20) unsigned | YES | | | | -| Succ | tinyint(1) unsigned | YES | | | | -| Plan_from_cache | tinyint(1) | YES | | | | -| Plan | longblob unsigned | YES | | | | -| Plan_digest | varchar(128) | YES | | | | -| Prev_stmt | longblob unsigned | YES | | | | -| Query | longblob unsigned | YES | | | | -+---------------------------+---------------------+------+-----+---------+-------+ -``` - -## CLUSTER_SLOW_QUERY table - -The `CLUSTER_SLOW_QUERY` table provides the slow query information of all nodes in the cluster, which is the parsing result of the TiDB slow log files. You can use the `CLUSTER_SLOW_QUERY` table the way you do with [`SLOW_QUERY`](#slow_query-table). The table schema of the `CLUSTER_SLOW_QUERY` table differs from that of the `SLOW_QUERY` table in that an `INSTANCE` column is added to `CLUSTER_SLOW_QUERY`. The `INSTANCE` column represents the TiDB node address of the row information on the slow query. For how to use this table to identify problematic statements and improve query performance, see [Slow Query Log Document](/identify-slow-queries.md). - -{{< copyable "sql" >}} - -```sql -desc information_schema.cluster_slow_query; -``` - -```sql -+---------------------------+---------------------+------+-----+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+---------------------------+---------------------+------+-----+---------+-------+ -| INSTANCE | varchar(64) | YES | | | | -| Time | timestamp unsigned | YES | | | | -| Txn_start_ts | bigint(20) unsigned | YES | | | | -| User | varchar(64) | YES | | | | -| Host | varchar(64) | YES | | | | -| Conn_ID | bigint(20) unsigned | YES | | | | -| Query_time | double unsigned | YES | | | | -| Parse_time | double unsigned | YES | | | | -| Compile_time | double unsigned | YES | | | | -| Prewrite_time | double unsigned | YES | | | | -| Wait_prewrite_binlog_time | double unsigned | YES | | | | -| Commit_time | double unsigned | YES | | | | -| Get_commit_ts_time | double unsigned | YES | | | | -| Commit_backoff_time | double unsigned | YES | | | | -| Backoff_types | varchar(64) | YES | | | | -| Resolve_lock_time | double unsigned | YES | | | | -| Local_latch_wait_time | double unsigned | YES | | | | -| Write_keys | bigint(22) unsigned | YES | | | | -| Write_size | bigint(22) unsigned | YES | | | | -| Prewrite_region | bigint(22) unsigned | YES | | | | -| Txn_retry | bigint(22) unsigned | YES | | | | -| Process_time | double unsigned | YES | | | | -| Wait_time | double unsigned | YES | | | | -| Backoff_time | double unsigned | YES | | | | -| LockKeys_time | double unsigned | YES | | | | -| Request_count | bigint(20) unsigned | YES | | | | -| Total_keys | bigint(20) unsigned | YES | | | | -| Process_keys | bigint(20) unsigned | YES | | | | -| DB | varchar(64) | YES | | | | -| Index_names | varchar(100) | YES | | | | -| Is_internal | tinyint(1) unsigned | YES | | | | -| Digest | varchar(64) | YES | | | | -| Stats | varchar(512) | YES | | | | -| Cop_proc_avg | double unsigned | YES | | | | -| Cop_proc_p90 | double unsigned | YES | | | | -| Cop_proc_max | double unsigned | YES | | | | -| Cop_proc_addr | varchar(64) | YES | | | | -| Cop_wait_avg | double unsigned | YES | | | | -| Cop_wait_p90 | double unsigned | YES | | | | -| Cop_wait_max | double unsigned | YES | | | | -| Cop_wait_addr | varchar(64) | YES | | | | -| Mem_max | bigint(20) unsigned | YES | | | | -| Succ | tinyint(1) unsigned | YES | | | | -| Plan_from_cache | tinyint(1) | YES | | | | -| Plan | longblob unsigned | YES | | | | -| Plan_digest | varchar(128) | YES | | | | -| Prev_stmt | longblob unsigned | YES | | | | -| Query | longblob unsigned | YES | | | | -+---------------------------+---------------------+------+-----+---------+-------+ -``` - -When the cluster system table is queried, TiDB does not obtain data from all nodes, but pushes down the related calculation to other nodes. The execution plan is as follows: - -{{< copyable "sql" >}} - -```sql -desc select count(*) from information_schema.cluster_slow_query where user = 'u1'; -``` - -``` -+--------------------------+----------+-----------+--------------------------+------------------------------------------------------+ -| id | estRows | task | access object | operator info | -+--------------------------+----------+-----------+--------------------------+------------------------------------------------------+ -| StreamAgg_20 | 1.00 | root | | funcs:count(Column#53)->Column#51 | -| └─TableReader_21 | 1.00 | root | | data:StreamAgg_9 | -| └─StreamAgg_9 | 1.00 | cop[tidb] | | funcs:count(1)->Column#53 | -| └─Selection_19 | 10.00 | cop[tidb] | | eq(information_schema.cluster_slow_query.user, "u1") | -| └─TableFullScan_18 | 10000.00 | cop[tidb] | table:CLUSTER_SLOW_QUERY | keep order:false, stats:pseudo | -+--------------------------+----------+-----------+--------------------------+------------------------------------------------------+ -``` - -In the above execution plan, the `user = u1` condition is pushed down to other (`cop`) TiDB nodes, and the aggregate operator is also pushed down (the `StreamAgg` operator in the graph). - -Currently, because statistics of the system tables are not collected, sometimes some aggregation operators cannot be pushed down, which results in slow execution. In this case, you can manually specify the SQL HINT to push down the aggregation operators. For example: - -{{< copyable "sql" >}} - -```sql -select /*+ AGG_TO_COP() */ count(*) from information_schema.cluster_slow_query group by user; -``` - -### STATISTICS table - -The `STATISTICS` table provides information about table indexes: - -{{< copyable "sql" >}} - -```sql -desc statistics; -``` - -``` -+---------------+---------------+------+------+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+---------------+---------------+------+------+---------+-------+ -| TABLE_CATALOG | varchar(512) | YES | | NULL | | -| TABLE_SCHEMA | varchar(64) | YES | | NULL | | -| TABLE_NAME | varchar(64) | YES | | NULL | | -| NON_UNIQUE | varchar(1) | YES | | NULL | | -| INDEX_SCHEMA | varchar(64) | YES | | NULL | | -| INDEX_NAME | varchar(64) | YES | | NULL | | -| SEQ_IN_INDEX | bigint(2) | YES | | NULL | | -| COLUMN_NAME | varchar(21) | YES | | NULL | | -| COLLATION | varchar(1) | YES | | NULL | | -| CARDINALITY | bigint(21) | YES | | NULL | | -| SUB_PART | bigint(3) | YES | | NULL | | -| PACKED | varchar(10) | YES | | NULL | | -| NULLABLE | varchar(3) | YES | | NULL | | -| INDEX_TYPE | varchar(16) | YES | | NULL | | -| COMMENT | varchar(16) | YES | | NULL | | -| INDEX_COMMENT | varchar(1024) | YES | | NULL | | -| IS_VISIBLE | varchar(3) | YES | | NULL | | -| Expression | varchar(64) | YES | | NULL | | -+---------------+---------------+------+------+---------+-------+ -``` - -The following statements are equivalent: - -```sql -SELECT * FROM INFORMATION_SCHEMA.STATISTICS - WHERE table_name = 'tbl_name' - AND table_schema = 'db_name' - -SHOW INDEX - FROM tbl_name - FROM db_name -``` - -### TABLES table - -The `TABLES` table provides information about tables in databases: - -{{< copyable "sql" >}} - -```sql -SELECT * FROM tables WHERE table_schema='mysql' AND table_name='user'; -``` - -``` -*************************** 1. row *************************** - TABLE_CATALOG: def - TABLE_SCHEMA: mysql - TABLE_NAME: user - TABLE_TYPE: BASE TABLE - ENGINE: InnoDB - VERSION: 10 - ROW_FORMAT: Compact - TABLE_ROWS: 0 - AVG_ROW_LENGTH: 0 - DATA_LENGTH: 0 - MAX_DATA_LENGTH: 0 - INDEX_LENGTH: 0 - DATA_FREE: 0 - AUTO_INCREMENT: 0 - CREATE_TIME: 2019-03-29 09:17:27 - UPDATE_TIME: NULL - CHECK_TIME: NULL - TABLE_COLLATION: utf8mb4_bin - CHECKSUM: NULL - CREATE_OPTIONS: - TABLE_COMMENT: - TIDB_TABLE_ID: 5 -TIDB_ROW_ID_SHARDING_INFO: NULL -1 row in set (0.00 sec) -``` - -The following statements are equivalent: - -```sql -SELECT table_name FROM INFORMATION_SCHEMA.TABLES - WHERE table_schema = 'db_name' - [AND table_name LIKE 'wild'] - -SHOW TABLES - FROM db_name - [LIKE 'wild'] -``` - -The description of columns in the `TABLES` table is as follows: - -* `TABLE_CATALOG`: The name of the catalog which the table belongs to. The value is always `def`. -* `TABLE_SCHEMA`: The name of the schema which the table belongs to. -* `TABLE_NAME`: The name of the table. -* `TABLE_TYPE`: The type of the table. -* `ENGINE`: The type of the storage engine. The value is currently `InnoDB`. -* `VERSION`: Version. The value is `10` by default. -* `ROW_FORMAT`: The row format. The value is currently `Compact`. -* `TABLE_ROWS`: The number of rows in the table in statistics. -* `AVG_ROW_LENGTH`: The average row length of the table. `AVG_ROW_LENGTH` = `DATA_LENGTH` / `TABLE_ROWS`. -* `DATA_LENGTH`: Data length. `DATA_LENGTH` = `TABLE_ROWS` \* the sum of storage lengths of the columns in the tuple. The replicas of TiKV are not taken into account. -* `MAX_DATA_LENGTH`: The maximum data length. The value is currently `0`, which means the data length has no upper limit. -* `INDEX_LENGTH`: The index length. `INDEX_LENGTH` = `TABLE_ROWS` \* the sum of lengths of the columns in the index tuple. The replicas of TiKV are not taken into account. -* `DATA_FREE`: Data fragment. The value is currently `0`. -* `AUTO_INCREMENT`: The current step of the auto-increment primary key. -* `CREATE_TIME`: The time at which the table is created. -* `UPDATE_TIME`: The time at which the table is updated. -* `CHECK_TIME`: The time at which the table is checked. -* `TABLE_COLLATION`: The collation of strings in the table. -* `CHECKSUM`: Checksum. -* `CREATE_OPTIONS`: Creates options. -* `TABLE_COMMENT`: The comments and notes of the table. - -Most of the information in the table is the same as MySQL. Only two columns are newly defined by TiDB: - -* `TIDB_TABLE_ID`: to indicate the internal ID of a table. This ID is unique in a TiDB cluster. -* `TIDDB_ROW_ID_SHARDING_INFO`: to indicate the sharding type of a table. The possible values are as follows: - - `"NOT_SHARDED"`: the table is not sharded. - - `"NOT_SHARDED(PK_IS_HANDLE)"`: the table that defines an integer Primary Key as its row id is not sharded. - - `"PK_AUTO_RANDOM_BITS={bit_number}"`: the table that defines an integer Primary Key as its row id is sharded because the Primary Key is assigned with `AUTO_RANDOM` attribute. - - `"SHARD_BITS={bit_number}"`: the table is sharded using `SHARD_ROW_ID_BITS={bit_number}`. - - NULL: the table is a system table or view, and thus cannot be sharded. - -### TABLE_CONSTRAINTS table - -The `TABLE_CONSTRAINTS` table describes which tables have constraints: - -{{< copyable "sql" >}} - -```sql -SELECT * FROM table_constraints WHERE constraint_type='UNIQUE'; -``` - -``` -*************************** 1. row *************************** -CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: name - TABLE_SCHEMA: mysql - TABLE_NAME: help_topic - CONSTRAINT_TYPE: UNIQUE -*************************** 2. row *************************** -CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: tbl - TABLE_SCHEMA: mysql - TABLE_NAME: stats_meta - CONSTRAINT_TYPE: UNIQUE -*************************** 3. row *************************** -CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: tbl - TABLE_SCHEMA: mysql - TABLE_NAME: stats_histograms - CONSTRAINT_TYPE: UNIQUE -*************************** 4. row *************************** -CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: tbl - TABLE_SCHEMA: mysql - TABLE_NAME: stats_buckets - CONSTRAINT_TYPE: UNIQUE -*************************** 5. row *************************** -CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: delete_range_index - TABLE_SCHEMA: mysql - TABLE_NAME: gc_delete_range - CONSTRAINT_TYPE: UNIQUE -*************************** 6. row *************************** -CONSTRAINT_CATALOG: def - CONSTRAINT_SCHEMA: mysql - CONSTRAINT_NAME: delete_range_done_index - TABLE_SCHEMA: mysql - TABLE_NAME: gc_delete_range_done - CONSTRAINT_TYPE: UNIQUE -6 rows in set (0.00 sec) -``` - -- The `CONSTRAINT_TYPE` value can be `UNIQUE`, `PRIMARY KEY`, or `FOREIGN KEY`. -- The `UNIQUE` and `PRIMARY KEY` information is similar to the result of the `SHOW INDEX` statement. - -### TIDB_HOT_REGIONS table - -The `TIDB_HOT_REGIONS` table provides information about hotspot Regions. - -{{< copyable "sql" >}} - -```sql -desc TIDB_HOT_REGIONS; -``` - -``` -+----------------+---------------------+------+-----+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+----------------+---------------------+------+-----+---------+-------+ -| TABLE_ID | bigint(21) unsigned | YES | | | | -| INDEX_ID | bigint(21) unsigned | YES | | | | -| DB_NAME | varchar(64) | YES | | | | -| TABLE_NAME | varchar(64) | YES | | | | -| INDEX_NAME | varchar(64) | YES | | | | -| TYPE | varchar(64) | YES | | | | -| MAX_HOT_DEGREE | bigint(21) unsigned | YES | | | | -| REGION_COUNT | bigint(21) unsigned | YES | | | | -| FLOW_BYTES | bigint(21) unsigned | YES | | | | -+----------------+---------------------+------+-----+---------+-------+ -``` - -The description of columns in the `TIDB_HOT_REGIONS` table is as follows: - -* `TABLE_ID`: ID of the table in which the hot Region is located. -* `INDEX_ID`: ID of the index in which the hot Region is located. -* `DB_NAME`: The database name of the object in which the hot Region is located. -* `TABLE_NAME`: The name of the table in which the hot Region is located. -* `INDEX_NAME`: The name of the index in which the hot Region is located. -* `REGION_ID`: ID of the hot Region. -* `TYPE`: The type of the hot Region. -* `MAX_HOT_DEGREE`: The maximum hot degree of the Region. -* `REGION_COUNT`: The number of Regions in the instance. -* `FLOW_BYTES`: The number of bytes written and read in the Region. - -### TIDB_INDEXES table - -The `TIDB_INDEXES` table provides the INDEX information of all tables. - -{{< copyable "sql" >}} - -```sql -desc TIDB_INDEXES; -``` - -``` -+---------------+---------------------+------+-----+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+---------------+---------------------+------+-----+---------+-------+ -| TABLE_SCHEMA | varchar(64) | YES | | | | -| TABLE_NAME | varchar(64) | YES | | | | -| NON_UNIQUE | bigint(21) unsigned | YES | | | | -| KEY_NAME | varchar(64) | YES | | | | -| SEQ_IN_INDEX | bigint(21) unsigned | YES | | | | -| COLUMN_NAME | varchar(64) | YES | | | | -| SUB_PART | bigint(21) unsigned | YES | | | | -| INDEX_COMMENT | varchar(2048) | YES | | | | -| INDEX_ID | bigint(21) unsigned | YES | | | | -+---------------+---------------------+------+-----+---------+-------+ -``` - -### TIKV_REGION_PEERS table - -The `TIKV_REGION_PEERS` table provides the peer information of all Regions. - -{{< copyable "sql" >}} - -```sql -desc TIKV_REGION_PEERS; -``` - -``` -+--------------+---------------------+------+-----+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+--------------+---------------------+------+-----+---------+-------+ -| REGION_ID | bigint(21) unsigned | YES | | | | -| PEER_ID | bigint(21) unsigned | YES | | | | -| STORE_ID | bigint(21) unsigned | YES | | | | -| IS_LEARNER | tinyint(1) unsigned | YES | | | | -| IS_LEADER | tinyint(1) unsigned | YES | | | | -| STATUS | varchar(10) | YES | | | | -| DOWN_SECONDS | bigint(21) unsigned | YES | | | | -+--------------+---------------------+------+-----+---------+-------+ -``` - -### TIKV_REGION_STATUS table - -The `TIKV_REGION_STATUS` table provides the status information of all Regions. - -{{< copyable "sql" >}} - -```sql -desc TIKV_REGION_STATUS; -``` - -``` -+------------------+---------------------+------+-----+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+------------------+---------------------+------+-----+---------+-------+ -| REGION_ID | bigint(21) unsigned | YES | | | | -| START_KEY | text | YES | | | | -| END_KEY | text | YES | | | | -| EPOCH_CONF_VER | bigint(21) unsigned | YES | | | | -| EPOCH_VERSION | bigint(21) unsigned | YES | | | | -| WRITTEN_BYTES | bigint(21) unsigned | YES | | | | -| READ_BYTES | bigint(21) unsigned | YES | | | | -| APPROXIMATE_SIZE | bigint(21) unsigned | YES | | | | -| APPROXIMATE_KEYS | bigint(21) unsigned | YES | | | | -+------------------+---------------------+------+-----+---------+-------+ -``` - -### TIKV_STORE_STATUS table - -The `TIKV_STORE_STATUS` table provides the status information of all TiKV Stores. - -{{< copyable "sql" >}} - -```sql -desc TIKV_STORE_STATUS; -``` - -``` -+-------------------+---------------------+------+-----+---------+-------+ -| Field | Type | Null | Key | Default | Extra | -+-------------------+---------------------+------+-----+---------+-------+ -| STORE_ID | bigint(21) unsigned | YES | | | | -| ADDRESS | varchar(64) | YES | | | | -| STORE_STATE | bigint(21) unsigned | YES | | | | -| STORE_STATE_NAME | varchar(64) | YES | | | | -| LABEL | json unsigned | YES | | | | -| VERSION | varchar(64) | YES | | | | -| CAPACITY | varchar(64) | YES | | | | -| AVAILABLE | varchar(64) | YES | | | | -| LEADER_COUNT | bigint(21) unsigned | YES | | | | -| LEADER_WEIGHT | bigint(21) unsigned | YES | | | | -| LEADER_SCORE | bigint(21) unsigned | YES | | | | -| LEADER_SIZE | bigint(21) unsigned | YES | | | | -| REGION_COUNT | bigint(21) unsigned | YES | | | | -| REGION_WEIGHT | bigint(21) unsigned | YES | | | | -| REGION_SCORE | bigint(21) unsigned | YES | | | | -| REGION_SIZE | bigint(21) unsigned | YES | | | | -| START_TS | datetime unsigned | YES | | | | -| LAST_HEARTBEAT_TS | datetime unsigned | YES | | | | -| UPTIME | varchar(64) | YES | | | | -+-------------------+---------------------+------+-----+---------+-------+ -``` - -### USER_PRIVILEGES table - -The `USER_PRIVILEGES` table provides information about global privileges. This information comes from the `mysql.user` system table: - -{{< copyable "sql" >}} - -```sql -desc USER_PRIVILEGES; -``` - -``` -+----------------|--------------|------|------|---------|-------+ -| Field | Type | Null | Key | Default | Extra | -+----------------|--------------|------|------|---------|-------+ -| GRANTEE | varchar(81) | YES | | NULL | | -| TABLE_CATALOG | varchar(512) | YES | | NULL | | -| PRIVILEGE_TYPE | varchar(64) | YES | | NULL | | -| IS_GRANTABLE | varchar(3) | YES | | NULL | | -+----------------|--------------|------|------|---------|-------+ -4 rows in set (0.00 sec) -``` - -### VIEWS table - -The `VIEWS` table provides information about SQL views: - -{{< copyable "sql" >}} - -```sql -create view test.v1 as select 1; -``` - -``` -Query OK, 0 rows affected (0.00 sec) -``` - -{{< copyable "sql" >}} - -```sql -select * from views; -``` - -``` -*************************** 1. row *************************** - TABLE_CATALOG: def - TABLE_SCHEMA: test - TABLE_NAME: v1 - VIEW_DEFINITION: select 1 - CHECK_OPTION: CASCADED - IS_UPDATABLE: NO - DEFINER: root@127.0.0.1 - SECURITY_TYPE: DEFINER -CHARACTER_SET_CLIENT: utf8 -COLLATION_CONNECTION: utf8_general_ci -1 row in set (0.00 sec) -``` - -## TIDB\_INDEXES table - -The `TIDB_INDEXES` table provides index-related information. - -{{< copyable "sql" >}} - -```sql -desc tidb_indexes\G -``` - -``` -*************************** 1. row *************************** - Table: TIDB_INDEXES -Create Table: CREATE TABLE `TIDB_INDEXES` ( - `TABLE_SCHEMA` varchar(64) DEFAULT NULL, - `TABLE_NAME` varchar(64) DEFAULT NULL, - `NON_UNIQUE` bigint(21) unsigned DEFAULT NULL, - `KEY_NAME` varchar(64) DEFAULT NULL, - `SEQ_IN_INDEX` bigint(21) unsigned DEFAULT NULL, - `COLUMN_NAME` varchar(64) DEFAULT NULL, - `SUB_PART` bigint(21) unsigned DEFAULT NULL, - `INDEX_COMMENT` varchar(2048) DEFAULT NULL, - `INDEX_ID` bigint(21) unsigned DEFAULT NULL -) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -1 row in set (0.00 sec) -``` - -`INDEX_ID` is the unique ID that TiDB allocates for each index. It can be used to do a join operation with `INDEX_ID` obtained from another table or API. - -For example, you can obtain `TABLE_ID` and `INDEX_ID` that are involved in some slow query in the [`SLOW_QUERY` table](#slow_query-table) and then obtain the specific index information using the following SQL statements: - -```sql -select - tidb_indexes.* -from - tidb_indexes, - tables -where - tidb_indexes.table_schema = tables.table_schema - and tidb_indexes.table_name = tidb_indexes.table_name - and tables.tidb_table_id = ? - and index_id = ? -``` - -## TIDB\_HOT\_REGIONS table - -The `TIDB_HOT_REGIONS` table provides the hot Region information in the current TiKV instance. - -{{< copyable "sql" >}} - -```sql -desc tidb_hot_regions\G -``` - -``` -*************************** 1. row *************************** - Table: TIDB_HOT_REGIONS -Create Table: CREATE TABLE `TIDB_HOT_REGIONS` ( - `TABLE_ID` bigint(21) unsigned DEFAULT NULL, - `INDEX_ID` bigint(21) unsigned DEFAULT NULL, - `DB_NAME` varchar(64) DEFAULT NULL, - `TABLE_NAME` varchar(64) DEFAULT NULL, - `INDEX_NAME` varchar(64) DEFAULT NULL, - `TYPE` varchar(64) DEFAULT NULL, - `MAX_HOT_DEGREE` bigint(21) unsigned DEFAULT NULL, - `REGION_COUNT` bigint(21) unsigned DEFAULT NULL, - `FLOW_BYTES` bigint(21) unsigned DEFAULT NULL -) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -1 row in set (0.00 sec) -``` - -- `TABLE_ID` and `INDEX_ID` are IDs generated for the corresponding table and index in TiDB. -- `TYPE` is the type for a hot Region. Its value can be `READ` or `WRITE`. - -## TIKV\_STORE\_STATUS table - -The `TIKV_STORE_STATUS` table shows some basic information of TiKV nodes via PD's API, like the ID allocated in the cluster, address and port, and status, capacity, and the number of Region leaders of the current node. - -{{< copyable "sql" >}} - -```sql -desc tikv_store_status\G -``` - -``` -*************************** 1. row *************************** - Table: TIKV_STORE_STATUS -Create Table: CREATE TABLE `TIKV_STORE_STATUS` ( - `STORE_ID` bigint(21) unsigned DEFAULT NULL, - `ADDRESS` varchar(64) DEFAULT NULL, - `STORE_STATE` bigint(21) unsigned DEFAULT NULL, - `STORE_STATE_NAME` varchar(64) DEFAULT NULL, - `LABEL` json unsigned DEFAULT NULL, - `VERSION` varchar(64) DEFAULT NULL, - `CAPACITY` varchar(64) DEFAULT NULL, - `AVAILABLE` varchar(64) DEFAULT NULL, - `LEADER_COUNT` bigint(21) unsigned DEFAULT NULL, - `LEADER_WEIGHT` bigint(21) unsigned DEFAULT NULL, - `LEADER_SCORE` bigint(21) unsigned DEFAULT NULL, - `LEADER_SIZE` bigint(21) unsigned DEFAULT NULL, - `REGION_COUNT` bigint(21) unsigned DEFAULT NULL, - `REGION_WEIGHT` bigint(21) unsigned DEFAULT NULL, - `REGION_SCORE` bigint(21) unsigned DEFAULT NULL, - `REGION_SIZE` bigint(21) unsigned DEFAULT NULL, - `START_TS` datetime unsigned DEFAULT NULL, - `LAST_HEARTBEAT_TS` datetime unsigned DEFAULT NULL, - `UPTIME` varchar(64) DEFAULT NULL -) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -1 row in set (0.01 sec) -``` - -## TIKV\_REGION\_STATUS table - -The `TIKV_REGION_STATUS` table shows some basic information of TiKV Regions via PD's API, like the Region ID, starting and ending key-values, and read and write traffic. - -{{< copyable "sql" >}} - -```sql -desc tikv_region_status\G -``` - -``` -*************************** 1. row *************************** - Table: TIKV_REGION_STATUS -Create Table: CREATE TABLE `TIKV_REGION_STATUS` ( - `REGION_ID` bigint(21) unsigned DEFAULT NULL, - `START_KEY` text DEFAULT NULL, - `END_KEY` text DEFAULT NULL, - `EPOCH_CONF_VER` bigint(21) unsigned DEFAULT NULL, - `EPOCH_VERSION` bigint(21) unsigned DEFAULT NULL, - `WRITTEN_BYTES` bigint(21) unsigned DEFAULT NULL, - `READ_BYTES` bigint(21) unsigned DEFAULT NULL, - `APPROXIMATE_SIZE` bigint(21) unsigned DEFAULT NULL, - `APPROXIMATE_KEYS` bigint(21) unsigned DEFAULT NULL -) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -1 row in set (0.00 sec) -``` - -You can implement the `top confver`, `top read` and `top write` operations in pd-ctl via the `ORDER BY X LIMIT Y` operation on the `EPOCH_CONF_VER`, `WRITTEN_BYTES` and `READ_BYTES` columns. - -You can query the top 3 Regions with the most write data using the following SQL statement: - -``` -select * from tikv_region_status order by written_bytes desc limit 3; -``` - -## TIKV\_REGION\_PEERS table - -The `TIKV_REGION_PEERS` table shows detailed information of a single Region node in TiKV, like whether it is a learner or leader. - -{{< copyable "sql" >}} - -```sql -desc tikv_region_peers\G -``` - -``` -*************************** 1. row *************************** - Table: TIKV_REGION_PEERS -Create Table: CREATE TABLE `TIKV_REGION_PEERS` ( - `REGION_ID` bigint(21) unsigned DEFAULT NULL, - `PEER_ID` bigint(21) unsigned DEFAULT NULL, - `STORE_ID` bigint(21) unsigned DEFAULT NULL, - `IS_LEARNER` tinyint(1) unsigned DEFAULT NULL, - `IS_LEADER` tinyint(1) unsigned DEFAULT NULL, - `STATUS` varchar(10) DEFAULT NULL, - `DOWN_SECONDS` bigint(21) unsigned DEFAULT NULL -) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -1 row in set (0.00 sec) -``` - -For example, you can query the specific TiKV addresses for the top 3 Regions with the maximum value of `WRITTEN_BYTES` using the following SQL statement: - -```sql -select - address, - tikv.address, - region.region_id, -from - tikv_store_status tikv, - tikv_region_peers peer, - ( - select - * - from - tikv_region_status region - order by - written_bytes desc limit 3 - ) - region -where - region.region_id = peer.region_id - and peer.is_leader = 1 - and peer.store_id = tikv.region_id -``` - -## ANALYZE\_STATUS table - -The `ANALYZE_STATUS` table shows the execution status of the `ANALYZE` command in the current cluster. - -{{< copyable "sql" >}} - -```sql -desc analyze_status\G -``` - -``` -*************************** 1. row *************************** - Table: ANALYZE_STATUS -Create Table: CREATE TABLE `ANALYZE_STATUS` ( - `TABLE_SCHEMA` varchar(64) DEFAULT NULL, - `TABLE_NAME` varchar(64) DEFAULT NULL, - `PARTITION_NAME` varchar(64) DEFAULT NULL, - `JOB_INFO` varchar(64) DEFAULT NULL, - `PROCESSED_ROWS` bigint(20) unsigned DEFAULT NULL, - `START_TIME` datetime unsigned DEFAULT NULL, - `STATE` varchar(64) DEFAULT NULL -) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -1 row in set (0.00 sec) -``` - -The `STATE` column shows the execution status of a specific `ANALYZE` task. Its value can be `pending`, `running`,`finished` or `failed`. - -## SLOW\_QUERY table - -The `SLOW_QUERY` table maps slow query logs. Its column names and field names of slow query logs have an one-to-one corresponse relationship. For details, see [Identify Slow Queries](/identify-slow-queries.md#identify-slow-queries). - -{{< copyable "sql" >}} - -```sql -desc slow_query\G -``` - -``` -*************************** 1. row *************************** - Table: SLOW_QUERY -Create Table: CREATE TABLE `SLOW_QUERY` ( - `Time` timestamp unsigned NULL DEFAULT NULL, - `Txn_start_ts` bigint(20) unsigned DEFAULT NULL, - `User` varchar(64) DEFAULT NULL, - `Host` varchar(64) DEFAULT NULL, - `Conn_ID` bigint(20) unsigned DEFAULT NULL, - `Query_time` double unsigned DEFAULT NULL, - `Process_time` double unsigned DEFAULT NULL, - `Wait_time` double unsigned DEFAULT NULL, - `Backoff_time` double unsigned DEFAULT NULL, - `Request_count` bigint(20) unsigned DEFAULT NULL, - `Total_keys` bigint(20) unsigned DEFAULT NULL, - `Process_keys` bigint(20) unsigned DEFAULT NULL, - `DB` varchar(64) DEFAULT NULL, - `Index_ids` varchar(100) DEFAULT NULL, - `Is_internal` tinyint(1) unsigned DEFAULT NULL, - `Digest` varchar(64) DEFAULT NULL, - `Stats` varchar(512) DEFAULT NULL, - `Cop_proc_avg` double unsigned DEFAULT NULL, - `Cop_proc_p90` double unsigned DEFAULT NULL, - `Cop_proc_max` double unsigned DEFAULT NULL, - `Cop_proc_addr` varchar(64) DEFAULT NULL, - `Cop_wait_avg` double unsigned DEFAULT NULL, - `Cop_wait_p90` double unsigned DEFAULT NULL, - `Cop_wait_max` double unsigned DEFAULT NULL, - `Cop_wait_addr` varchar(64) DEFAULT NULL, - `Mem_max` bigint(20) unsigned DEFAULT NULL, - `Query` varchar(4096) DEFAULT NULL -) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin -1 row in set (0.00 sec) -``` - -## Unsupported Information Schema Tables - -The following `INFORMATION_SCHEMA` tables are present in TiDB, but will always return zero rows: - -* `COLUMN_PRIVILEGES` -* `EVENTS` -* `FILES` -* `GLOBAL_STATUS` -* `GLOBAL_VARIABLES` -* `OPTIMIZER_TRACE` -* `PARAMETERS` -* `PARTITIONS` -* `PLUGINS` -* `PROFILING` -* `REFERENTIAL_CONSTRAINTS` -* `ROUTINES` -* `SCHEMA_PRIVILEGES` -* `SESSION_STATUS` -* `TABLESPACES` -* `TABLE_PRIVILEGES` -* `TRIGGERS` From 74f813391fd4806bc2f630cd9054775092fea684 Mon Sep 17 00:00:00 2001 From: Ran Date: Tue, 21 Jul 2020 16:35:25 +0800 Subject: [PATCH 8/8] Update information-schema-character-sets.md --- information-schema/information-schema-character-sets.md | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/information-schema/information-schema-character-sets.md b/information-schema/information-schema-character-sets.md index 3c7939cf5ddf8..c579e9c27fe05 100644 --- a/information-schema/information-schema-character-sets.md +++ b/information-schema/information-schema-character-sets.md @@ -43,4 +43,11 @@ SELECT * FROM `character_sets`; | binary | binary | binary | 1 | +--------------------+----------------------+---------------+--------+ 5 rows in set (0.00 sec) -``` \ No newline at end of file +``` + +The description of columns in the `CHARACTER_SETS` table is as follows: + +* `CHARACTER_SET_NAME`: The name of the character set. +* `DEFAULT_COLLATE_NAME` The default collation name of the character set. +* `DESCRIPTION` The description of the character set. +* `MAXLEN` The maximum length required to store a character in this character set.