Added COM_SEND_REPLICA_STATISTICS & background thread to send lag sta…

…tistics from secondary to primary and store it in information_schema.replica_statistics

Summary:
* I am adding a new RPC `COM_SEND_REPLICA_STATISTICS`. Slaves will use this RPC to send lag statistics to master. This will be done in the next diff.

* In addition, I have added the information_schema table named `replica_statistics` to store the slave lag stats.

* Added a new background thread that is started when the `mysqld` process starts and continuously publishes lag statistics from slaves to master every `slave_stats_daemon_interval` seconds.

The default values of `slave_stats_daemon_interval` is set to 0, which means do not send lag statistics to master. The unit for this sys_var is seconds.

**Points to note -**

* The background thread re-uses the connection to master to send stats. It does not reconnect every cycle.
* If it is not able to connect to the master in one cycle, it retries the connection in successive cycles until it is able to connect. After this point, it reuses the same connection.
* In case of topology changes, the thread is able to reconnect to the new master and send stats.

Reviewed By: mzait, lth

Differential Revision: D21440060

fbshipit-source-id: 9178c96

include/mysql.h.pp

@@ -13,7 +13,8 @@
   COM_STMT_RESET, COM_SET_OPTION, COM_STMT_FETCH, COM_DAEMON,
   COM_BINLOG_DUMP_GTID, COM_RESET_CONNECTION,
   COM_END,
-  COM_TOP_END = 254,
+  COM_TOP_END = 253,
+  COM_SEND_REPLICA_STATISTICS = 254,
   COM_QUERY_ATTRS = 255,
   COM_MAX = 256,
 };

include/mysql_com.h

@@ -91,7 +91,8 @@ enum enum_server_command
     The following are Facebook specific commands. They are put at the top end
     to avoid conflicting with upstream.
   */
-  COM_TOP_END = 254,
+  COM_TOP_END = 253,
+  COM_SEND_REPLICA_STATISTICS = 254,
   COM_QUERY_ATTRS = 255,
   COM_MAX = 256,
 };
@@ -784,8 +785,8 @@ typedef struct st_udf_init
   char *ptr;                   /* free pointer for function data */
   my_bool const_item;          /* 1 if function always returns the same value */
   void *extension;
-} UDF_INIT;
-/* 
+} UDF_INIT; 
+/*
   TODO: add a notion for determinism of the UDF. 
   See Item_udf_func::update_used_tables ()
 */

mysql-test/include/check-testcase.test

@@ -83,6 +83,7 @@ if ($tmp)
   --echo Master_SSL_Actual_Cipher	#
   --echo Master_SSL_Subject	#
   --echo Master_SSL_Issuer	#
+  --echo Slave_Lag_Stats_Thread_Running	No
 }
 if (!$tmp) {
   # Note: after WL#5177, fields 13-18 shall not be filtered-out.

mysql-test/r/disabled_replication.result

@@ -1,5 +1,5 @@
 SHOW SLAVE STATUS;
-Slave_IO_State	Master_Host	Master_User	Master_Port	Connect_Retry	Master_Log_File	Read_Master_Log_Pos	Relay_Log_File	Relay_Log_Pos	Relay_Master_Log_File	Slave_IO_Running	Slave_SQL_Running	Replicate_Do_DB	Replicate_Ignore_DB	Replicate_Do_Table	Replicate_Ignore_Table	Replicate_Wild_Do_Table	Replicate_Wild_Ignore_Table	Last_Errno	Last_Symbolic_Errno	Last_Error	Skip_Counter	Exec_Master_Log_Pos	Relay_Log_Space	Until_Condition	Until_Log_File	Until_Log_Pos	Master_SSL_Allowed	Master_SSL_CA_File	Master_SSL_CA_Path	Master_SSL_Cert	Master_SSL_Cipher	Master_SSL_Key	Seconds_Behind_Master	Lag_Peak_Over_Last_Period	Master_SSL_Verify_Server_Cert	Last_IO_Errno	Last_IO_Error	Last_SQL_Errno	Last_SQL_Error	Replicate_Ignore_Server_Ids	Master_Server_Id	Master_UUID	Master_Info_File	SQL_Delay	SQL_Remaining_Delay	Slave_SQL_Running_State	Master_Retry_Count	Master_Bind	Last_IO_Error_Timestamp	Last_SQL_Error_Timestamp	Master_SSL_Crl	Master_SSL_Crlpath	Retrieved_Gtid_Set	Executed_Gtid_Set	Auto_Position	Master_SSL_Actual_Cipher	Master_SSL_Subject	Master_SSL_Issuer
+Slave_IO_State	Master_Host	Master_User	Master_Port	Connect_Retry	Master_Log_File	Read_Master_Log_Pos	Relay_Log_File	Relay_Log_Pos	Relay_Master_Log_File	Slave_IO_Running	Slave_SQL_Running	Replicate_Do_DB	Replicate_Ignore_DB	Replicate_Do_Table	Replicate_Ignore_Table	Replicate_Wild_Do_Table	Replicate_Wild_Ignore_Table	Last_Errno	Last_Symbolic_Errno	Last_Error	Skip_Counter	Exec_Master_Log_Pos	Relay_Log_Space	Until_Condition	Until_Log_File	Until_Log_Pos	Master_SSL_Allowed	Master_SSL_CA_File	Master_SSL_CA_Path	Master_SSL_Cert	Master_SSL_Cipher	Master_SSL_Key	Seconds_Behind_Master	Lag_Peak_Over_Last_Period	Master_SSL_Verify_Server_Cert	Last_IO_Errno	Last_IO_Error	Last_SQL_Errno	Last_SQL_Error	Replicate_Ignore_Server_Ids	Master_Server_Id	Master_UUID	Master_Info_File	SQL_Delay	SQL_Remaining_Delay	Slave_SQL_Running_State	Master_Retry_Count	Master_Bind	Last_IO_Error_Timestamp	Last_SQL_Error_Timestamp	Master_SSL_Crl	Master_SSL_Crlpath	Retrieved_Gtid_Set	Executed_Gtid_Set	Auto_Position	Master_SSL_Actual_Cipher	Master_SSL_Subject	Master_SSL_Issuer	Slave_Lag_Stats_Thread_Running
 RESET SLAVE;
 ERROR HY000: Slave is not configured or failed to initialize properly. You must at least set --server-id to enable either a master or a slave. Additional error messages can be found in the MySQL error log.
 SHOW RELAYLOG EVENTS;

mysql-test/r/information_schema-big.result

@@ -67,6 +67,7 @@ VIEWS	TABLE_SCHEMA
 AUTHINFO	ID
 SLAVE_DB_LOAD	DB
 RBR_BI_INCONSISTENCIES	TABLE
+REPLICA_STATISTICS	SERVER_ID
 SCHEMATA_EXT	SCHEMA_NAME
 SOCKET_DIAG_SLAVES	ID
 USER_TABLE_STATISTICS	TABLE_SCHEMA
@@ -141,6 +142,7 @@ VIEWS	TABLE_SCHEMA
 AUTHINFO	ID
 SLAVE_DB_LOAD	DB
 RBR_BI_INCONSISTENCIES	TABLE
+REPLICA_STATISTICS	SERVER_ID
 SCHEMATA_EXT	SCHEMA_NAME
 SOCKET_DIAG_SLAVES	ID
 USER_TABLE_STATISTICS	TABLE_SCHEMA

mysql-test/r/information_schema.result

@@ -99,6 +99,7 @@ VIEWS
 AUTHINFO
 SLAVE_DB_LOAD
 RBR_BI_INCONSISTENCIES
+REPLICA_STATISTICS
 SCHEMATA_EXT
 SOCKET_DIAG_SLAVES
 USER_TABLE_STATISTICS
@@ -886,6 +887,7 @@ TABLES	CREATE_TIME	datetime
 TABLES	UPDATE_TIME	datetime
 TABLES	CHECK_TIME	datetime
 TRIGGERS	CREATED	datetime
+REPLICA_STATISTICS	TIMESTAMP	datetime
 SQL_STATISTICS	QUERY_SAMPLE_SEEN	datetime
 event	execute_at	datetime
 event	last_executed	datetime
@@ -954,7 +956,7 @@ table_schema IN ('mysql', 'INFORMATION_SCHEMA', 'test', 'mysqltest')
 AND table_name not like 'ndb%' AND table_name not like 'innodb_%'  AND table_name not like 'rocksdb_%'
 GROUP BY TABLE_SCHEMA;
 table_schema	count(*)
-information_schema	56
+information_schema	57
 mysql	27
 create table t1 (i int, j int);
 create trigger trg1 before insert on t1 for each row
@@ -1425,6 +1427,7 @@ QUERY_ATTRIBUTES	information_schema.QUERY_ATTRIBUTES	1
 QUERY_PERF_COUNTER	information_schema.QUERY_PERF_COUNTER	1
 RBR_BI_INCONSISTENCIES	information_schema.RBR_BI_INCONSISTENCIES	1
 REFERENTIAL_CONSTRAINTS	information_schema.REFERENTIAL_CONSTRAINTS	1
+REPLICA_STATISTICS	information_schema.REPLICA_STATISTICS	1
 ROUTINES	information_schema.ROUTINES	1
 SCHEMATA	information_schema.SCHEMATA	1
 SCHEMATA_EXT	information_schema.SCHEMATA_EXT	1

mysql-test/r/information_schema_db.result

@@ -51,6 +51,7 @@ VIEWS
 AUTHINFO
 SLAVE_DB_LOAD
 RBR_BI_INCONSISTENCIES
+REPLICA_STATISTICS
 SCHEMATA_EXT
 SOCKET_DIAG_SLAVES
 USER_TABLE_STATISTICS

mysql-test/r/mysqld--help-notwin-profiling.result

@@ -1932,6 +1932,10 @@ The following options may be given as the first argument:
  network before writing them to the relay log. Enabled by
  default.
  (Defaults to on; use --skip-slave-sql-verify-checksum to disable.)
+ --slave-stats-daemon-interval=# 
+ Period(seconds) for the background thread responsible for
+ sending slave lag statistics to master.New period is
+ applied after the current period finishes.
  --slave-transaction-retries=# 
  Number of times the slave SQL thread will retry a
  transaction in case it failed with a deadlock or elapsed
@@ -2454,7 +2458,7 @@ performance-schema-max-rwlock-instances -1
 performance-schema-max-socket-classes 10
 performance-schema-max-socket-instances -1
 performance-schema-max-stage-classes 150
-performance-schema-max-statement-classes 187
+performance-schema-max-statement-classes 188
 performance-schema-max-table-handles -1
 performance-schema-max-table-instances -1
 performance-schema-max-thread-classes 50
@@ -2725,6 +2729,7 @@ slave-rows-search-algorithms TABLE_SCAN,INDEX_SCAN
 slave-run-triggers-for-rbr NO
 slave-skip-errors (No default value)
 slave-sql-verify-checksum TRUE
+slave-stats-daemon-interval 0
 slave-transaction-retries 10
 slave-tx-isolation REPEATABLE-READ
 slave-type-conversions 

mysql-test/r/mysqld--help-notwin.result

@@ -1930,6 +1930,10 @@ The following options may be given as the first argument:
  network before writing them to the relay log. Enabled by
  default.
  (Defaults to on; use --skip-slave-sql-verify-checksum to disable.)
+ --slave-stats-daemon-interval=# 
+ Period(seconds) for the background thread responsible for
+ sending slave lag statistics to master.New period is
+ applied after the current period finishes.
  --slave-transaction-retries=# 
  Number of times the slave SQL thread will retry a
  transaction in case it failed with a deadlock or elapsed
@@ -2452,7 +2456,7 @@ performance-schema-max-rwlock-instances -1
 performance-schema-max-socket-classes 10
 performance-schema-max-socket-instances -1
 performance-schema-max-stage-classes 150
-performance-schema-max-statement-classes 187
+performance-schema-max-statement-classes 188
 performance-schema-max-table-handles -1
 performance-schema-max-table-instances -1
 performance-schema-max-thread-classes 50
@@ -2722,6 +2726,7 @@ slave-rows-search-algorithms TABLE_SCAN,INDEX_SCAN
 slave-run-triggers-for-rbr NO
 slave-skip-errors (No default value)
 slave-sql-verify-checksum TRUE
+slave-stats-daemon-interval 0
 slave-transaction-retries 10
 slave-tx-isolation REPEATABLE-READ
 slave-type-conversions 

mysql-test/r/mysqlshow.result

@@ -136,6 +136,7 @@ DROP TABLE t1, t2;
 | QUERY_PERF_COUNTER                    |
 | RBR_BI_INCONSISTENCIES                |
 | REFERENTIAL_CONSTRAINTS               |
+| REPLICA_STATISTICS                    |
 | ROCKSDB_CFSTATS                       |
 | ROCKSDB_CF_OPTIONS                    |
 | ROCKSDB_COMPACTION_STATS              |
@@ -235,6 +236,7 @@ DROP TABLE t1, t2;
 | QUERY_PERF_COUNTER                    |
 | RBR_BI_INCONSISTENCIES                |
 | REFERENTIAL_CONSTRAINTS               |
+| REPLICA_STATISTICS                    |
 | ROCKSDB_CFSTATS                       |
 | ROCKSDB_CF_OPTIONS                    |
 | ROCKSDB_COMPACTION_STATS              |

mysql-test/r/slave_stats_daemon.result

@@ -0,0 +1,101 @@
+include/master-slave.inc
+Warnings:
+Note	####	Sending passwords in plain text without SSL/TLS is extremely insecure.
+Note	####	Storing MySQL user name or password information in the master info repository is not secure and is therefore not recommended. Please consider using the USER and PASSWORD connection options for START SLAVE; see the 'START SLAVE Syntax' in the MySQL Manual for more information.
+[connection master]
+select @@slave_stats_daemon_interval;
+@@slave_stats_daemon_interval
+0
+select sleep(2);
+sleep(2)
+0
+select count(*) = 0 as stats_samples_collected from information_schema.replica_statistics;
+stats_samples_collected
+1
+set @@GLOBAL.slave_stats_daemon_interval=1;
+select @@slave_stats_daemon_interval;
+@@slave_stats_daemon_interval
+1
+select sleep(2);
+sleep(2)
+0
+select count(*) > 0 as stats_samples_collected from information_schema.replica_statistics;
+stats_samples_collected
+1
+set @@GLOBAL.slave_stats_daemon_interval=1;
+select @@slave_stats_daemon_interval;
+@@slave_stats_daemon_interval
+1
+select sleep(1);
+sleep(1)
+0
+select count(*) > 0 as stats_samples_collected from information_schema.replica_statistics;
+stats_samples_collected
+1
+select sleep(1);
+sleep(1)
+0
+select count(*) > 0 as stats_samples_collected from information_schema.replica_statistics;
+stats_samples_collected
+1
+set @@GLOBAL.slave_stats_daemon_interval=1;
+Master_User = 'root'
+Master_Host = '127.0.0.1'
+include/stop_slave.inc
+change master to master_user='test';
+Warnings:
+Note	1759	Sending passwords in plain text without SSL/TLS is extremely insecure.
+Note	1760	Storing MySQL user name or password information in the master info repository is not secure and is therefore not recommended. Please consider using the USER and PASSWORD connection options for START SLAVE; see the 'START SLAVE Syntax' in the MySQL Manual for more information.
+start slave;
+Master_User = 'test'
+Master_Host = '127.0.0.1'
+select sleep(2);
+sleep(2)
+0
+select now() - max(timestamp) > 1 as more_than_1_sec_old_most_recent_stats from information_schema.replica_statistics;
+more_than_1_sec_old_most_recent_stats
+1
+include/stop_slave.inc
+change master to master_user='root';
+Warnings:
+Note	1759	Sending passwords in plain text without SSL/TLS is extremely insecure.
+Note	1760	Storing MySQL user name or password information in the master info repository is not secure and is therefore not recommended. Please consider using the USER and PASSWORD connection options for START SLAVE; see the 'START SLAVE Syntax' in the MySQL Manual for more information.
+include/start_slave.inc
+Master_User = 'root'
+Master_Host = '127.0.0.1'
+select sleep(2);
+sleep(2)
+0
+select now() - max(timestamp) <= 1 as less_than_1_sec_old_most_recent_stats from information_schema.replica_statistics;
+less_than_1_sec_old_most_recent_stats
+1
+set @@GLOBAL.slave_stats_daemon_interval=1;
+set @@GLOBAL.slave_stats_daemon_interval=1;
+select * from information_schema.replica_statistics;
+SERVER_ID	TIMESTAMP	MILLI_SEC_BEHIND_MASTER
+Stop slave;
+reset slave all;
+CHANGE MASTER TO MASTER_HOST= 'MASTER_HOST', MASTER_USER= 'root', MASTER_PORT= MASTER_PORT;;
+Warnings:
+Note	1759	Sending passwords in plain text without SSL/TLS is extremely insecure.
+Note	1760	Storing MySQL user name or password information in the master info repository is not secure and is therefore not recommended. Please consider using the USER and PASSWORD connection options for START SLAVE; see the 'START SLAVE Syntax' in the MySQL Manual for more information.
+start slave;
+select sleep(2);
+sleep(2)
+0
+select sleep(2);
+sleep(2)
+0
+select count(*) > 0 as stats_samples_collected from information_schema.replica_statistics;
+stats_samples_collected
+1
+set @@GLOBAL.slave_stats_daemon_interval=0;
+Stop slave;
+reset slave all;
+set @@GLOBAL.slave_stats_daemon_interval=0;
+CHANGE MASTER TO MASTER_HOST= 'MASTER_HOST', MASTER_USER= 'root', MASTER_PORT= MASTER_PORT;;
+Warnings:
+Note	1759	Sending passwords in plain text without SSL/TLS is extremely insecure.
+Note	1760	Storing MySQL user name or password information in the master info repository is not secure and is therefore not recommended. Please consider using the USER and PASSWORD connection options for START SLAVE; see the 'START SLAVE Syntax' in the MySQL Manual for more information.
+start slave;
+include/rpl_end.inc

mysql-test/suite/funcs_1/r/is_columns_is.result

@@ -272,6 +272,9 @@ def	information_schema	REFERENTIAL_CONSTRAINTS	UNIQUE_CONSTRAINT_CATALOG	4		NO	v
 def	information_schema	REFERENTIAL_CONSTRAINTS	UNIQUE_CONSTRAINT_NAME	6	NULL	YES	varchar	64	192	NULL	NULL	NULL	utf8	utf8_general_ci	varchar(64)			select	
 def	information_schema	REFERENTIAL_CONSTRAINTS	UNIQUE_CONSTRAINT_SCHEMA	5		NO	varchar	64	192	NULL	NULL	NULL	utf8	utf8_general_ci	varchar(64)			select	
 def	information_schema	REFERENTIAL_CONSTRAINTS	UPDATE_RULE	8		NO	varchar	64	192	NULL	NULL	NULL	utf8	utf8_general_ci	varchar(64)			select	
+def	information_schema	REPLICA_STATISTICS	MILLI_SEC_BEHIND_MASTER	3	0	NO	bigint	NULL	NULL	19	0	NULL	NULL	NULL	bigint(21)			select	
+def	information_schema	REPLICA_STATISTICS	SERVER_ID	1	0	NO	bigint	NULL	NULL	19	0	NULL	NULL	NULL	bigint(21)			select	
+def	information_schema	REPLICA_STATISTICS	TIMESTAMP	2	0000-00-00 00:00:00	NO	datetime	NULL	NULL	NULL	NULL	0	NULL	NULL	datetime			select	
 def	information_schema	ROUTINES	CHARACTER_MAXIMUM_LENGTH	7	NULL	YES	int	NULL	NULL	10	0	NULL	NULL	NULL	int(21)			select	
 def	information_schema	ROUTINES	CHARACTER_OCTET_LENGTH	8	NULL	YES	int	NULL	NULL	10	0	NULL	NULL	NULL	int(21)			select	
 def	information_schema	ROUTINES	CHARACTER_SET_CLIENT	29		NO	varchar	32	96	NULL	NULL	NULL	utf8	utf8_general_ci	varchar(32)			select	
@@ -986,6 +989,9 @@ NULL	information_schema	QUERY_PERF_COUNTER	NUM_QUERIES	bigint	NULL	NULL	NULL	NUL
 3.0000	information_schema	REFERENTIAL_CONSTRAINTS	DELETE_RULE	varchar	64	192	utf8	utf8_general_ci	varchar(64)
 3.0000	information_schema	REFERENTIAL_CONSTRAINTS	TABLE_NAME	varchar	64	192	utf8	utf8_general_ci	varchar(64)
 3.0000	information_schema	REFERENTIAL_CONSTRAINTS	REFERENCED_TABLE_NAME	varchar	64	192	utf8	utf8_general_ci	varchar(64)
+NULL	information_schema	REPLICA_STATISTICS	SERVER_ID	bigint	NULL	NULL	NULL	NULL	bigint(21)
+NULL	information_schema	REPLICA_STATISTICS	TIMESTAMP	datetime	NULL	NULL	NULL	NULL	datetime
+NULL	information_schema	REPLICA_STATISTICS	MILLI_SEC_BEHIND_MASTER	bigint	NULL	NULL	NULL	NULL	bigint(21)
 3.0000	information_schema	ROUTINES	SPECIFIC_NAME	varchar	64	192	utf8	utf8_general_ci	varchar(64)
 3.0000	information_schema	ROUTINES	ROUTINE_CATALOG	varchar	512	1536	utf8	utf8_general_ci	varchar(512)
 3.0000	information_schema	ROUTINES	ROUTINE_SCHEMA	varchar	64	192	utf8	utf8_general_ci	varchar(64)

mysql-test/suite/funcs_1/r/is_tables_is.result

@@ -705,6 +705,29 @@ user_comment
 Separator	-----------------------------------------------------
 TABLE_CATALOG	def
 TABLE_SCHEMA	information_schema
+TABLE_NAME	REPLICA_STATISTICS
+TABLE_TYPE	SYSTEM VIEW
+ENGINE	MEMORY
+VERSION	10
+ROW_FORMAT	Fixed
+TABLE_ROWS	#TBLR#
+AVG_ROW_LENGTH	#ARL#
+DATA_LENGTH	#DL#
+MAX_DATA_LENGTH	#MDL#
+INDEX_LENGTH	#IL#
+DATA_FREE	#DF#
+AUTO_INCREMENT	NULL
+CREATE_TIME	#CRT#
+UPDATE_TIME	#UT#
+CHECK_TIME	#CT#
+TABLE_COLLATION	utf8_general_ci
+CHECKSUM	NULL
+CREATE_OPTIONS	#CO#
+TABLE_COMMENT	#TC#
+user_comment	
+Separator	-----------------------------------------------------
+TABLE_CATALOG	def
+TABLE_SCHEMA	information_schema
 TABLE_NAME	ROUTINES
 TABLE_TYPE	SYSTEM VIEW
 ENGINE	MyISAM
@@ -1987,6 +2010,29 @@ user_comment
 Separator	-----------------------------------------------------
 TABLE_CATALOG	def
 TABLE_SCHEMA	information_schema
+TABLE_NAME	REPLICA_STATISTICS
+TABLE_TYPE	SYSTEM VIEW
+ENGINE	MEMORY
+VERSION	10
+ROW_FORMAT	Fixed
+TABLE_ROWS	#TBLR#
+AVG_ROW_LENGTH	#ARL#
+DATA_LENGTH	#DL#
+MAX_DATA_LENGTH	#MDL#
+INDEX_LENGTH	#IL#
+DATA_FREE	#DF#
+AUTO_INCREMENT	NULL
+CREATE_TIME	#CRT#
+UPDATE_TIME	#UT#
+CHECK_TIME	#CT#
+TABLE_COLLATION	utf8_general_ci
+CHECKSUM	NULL
+CREATE_OPTIONS	#CO#
+TABLE_COMMENT	#TC#
+user_comment	
+Separator	-----------------------------------------------------
+TABLE_CATALOG	def
+TABLE_SCHEMA	information_schema
 TABLE_NAME	ROUTINES
 TABLE_TYPE	SYSTEM VIEW
 ENGINE	MyISAM

mysql-test/suite/perfschema/r/dml_setup_instruments.result

@@ -45,10 +45,10 @@ wait/synch/cond/sql/COND_flush_thread_cache	YES	YES
 wait/synch/cond/sql/COND_manager	YES	YES
 wait/synch/cond/sql/COND_queue_state	YES	YES
 wait/synch/cond/sql/COND_server_started	YES	YES
+wait/synch/cond/sql/COND_slave_stats_daemon	YES	YES
 wait/synch/cond/sql/COND_thread_cache	YES	YES
 wait/synch/cond/sql/COND_thread_count	YES	YES
 wait/synch/cond/sql/Delayed_insert::cond	YES	YES
-wait/synch/cond/sql/Delayed_insert::cond_client	YES	YES
 select * from performance_schema.setup_instruments
 where name='Wait';
 select * from performance_schema.setup_instruments

mysql-test/suite/sys_vars/r/slave_stats_daemon_interval_basic.result

@@ -0,0 +1,25 @@
+Default value of slave_stats_daemon_interval is 0
+SELECT @@global.slave_stats_daemon_interval;
+@@global.slave_stats_daemon_interval
+0
+SELECT @@session.slave_stats_daemon_interval;
+ERROR HY000: Variable 'slave_stats_daemon_interval' is a GLOBAL variable
+Expected error 'Variable is a GLOBAL variable'
+slave_stats_daemon_interval is a dynamic variable (change to 1)
+set @@global.slave_stats_daemon_interval = 1;
+SELECT @@global.slave_stats_daemon_interval;
+@@global.slave_stats_daemon_interval
+1
+restore the default value
+SET @@global.slave_stats_daemon_interval = 0;
+SELECT @@global.slave_stats_daemon_interval;
+@@global.slave_stats_daemon_interval
+0
+restart the server with non default value (1)
+SELECT @@global.slave_stats_daemon_interval;
+@@global.slave_stats_daemon_interval
+1
+restart the server with the default value (0)
+SELECT @@global.slave_stats_daemon_interval;
+@@global.slave_stats_daemon_interval
+0