sql: add a note about FULLTEXT

[hfxsd]

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[dveeden]

mysql> CREATE TABLE t1 (id INT PRIMARY KEY, v VARCHAR(255), INDEX (v) USING BTREE);
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE t2 (id INT PRIMARY KEY, v VARCHAR(255), INDEX (v) USING HASH);
Query OK, 0 rows affected (0.01 sec)

mysql> SHOW CREATE TABLE t1\G
*************************** 1. row ***************************
       Table: t1
Create Table: CREATE TABLE `t1` (
  `id` int(11) NOT NULL,
  `v` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */,
  KEY `v` (`v`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)

mysql> SHOW CREATE TABLE t2\G
*************************** 1. row ***************************
       Table: t2
Create Table: CREATE TABLE `t2` (
  `id` int(11) NOT NULL,
  `v` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */,
  KEY `v` (`v`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)

mysql> SHOW INDEX FROM t1;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression | Clustered |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
| t1    |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | YES     | NULL       | YES       |
| t1    |          1 | v        |            1 | v           | A         |           0 |     NULL | NULL   | YES  | BTREE      |         |               | YES     | NULL       | NO        |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
2 rows in set (0.00 sec)

mysql> SHOW INDEX FROM t2;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression | Clustered |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
| t2    |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | YES     | NULL       | YES       |
| t2    |          1 | v        |            1 | v           | A         |           0 |     NULL | NULL   | YES  | HASH       |         |               | YES     | NULL       | NO        |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
2 rows in set (0.00 sec)

So we support FULLTEXT and HASH syntax wise. Where FULLTEXT results in a warning, this isn't the case for HASH. Note that the index type for hash persists in the output of SHOW INDEX, but not in the output of SHOW CREATE TABLE.

[dveeden]

Note that these pages should have a note about FULLTEXT:

• sql-statements/sql-statement-add-index.md
• sql-statements/sql-statement-create-index.md
• sql-statements/sql-statement-create-table.md

Note that the "CREATE INDEX" page already has a complete note about this: "TiDB supports parsing the FULLTEXT and SPATIAL syntax but does not support using the FULLTEXT, HASH, and SPATIAL indexes."

Note that mysql-compatibility.md has a note about HASH being supported, but ignored.

[dveeden]

@kennytm looks like "USING" for index type is missing from the EBNF for "CREATE TABLE"?

[dveeden]

mysql> CREATE TABLE t3 (id INT PRIMARY KEY, v VARCHAR(255), INDEX (v) USING RTREE);
Query OK, 0 rows affected (0.01 sec)

mysql> SHOW INDEX FROM t3;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression | Clustered |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
| t3    |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               | YES     | NULL       | YES       |
| t3    |          1 | v        |            1 | v           | A         |           0 |     NULL | NULL   | YES  | RTREE      |         |               | YES     | NULL       | NO        |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+-----------+
2 rows in set (0.00 sec)

Note that RTREE is also accepted as index type (and ignored).

[dveeden]

Not that TiDB supports parsing the `FULLTEXT` and `SPATIAL` syntax from sql-statements/sql-statement-create-index.md is incorrect as far as I know. I don't think we support ...SPATIAL INDEX... syntax.

[dveeden]

Maybe we should also add a note about the (meaningless) Index_type in the output to this page? https://docs.pingcap.com/tidb/stable/sql-statement-show-indexes

[hfxsd]

Maybe we should also add a note about the (meaningless) Index_type in the output to this page? docs.pingcap.com/tidb/stable/sql-statement-show-indexes

OK, updated.

[dveeden]

I think the IndexOption of the create table statement page should be changed to:

IndexOption ::=
    'COMMENT' String
|   ( 'VISIBLE' | 'INVISIBLE' )
|   ('USING' | 'TYPE') ('BTREE' | 'RTREE' | 'HASH')

[dveeden]

Looks like these pages reference IndexInvisible but that's never defined. cc @kennytm

[kennytm]

@dveeden If any EBNF references IndexInvisible the node should be replaced with ("VISIBLE" | "INVISIBLE").

If you want a hyperlink it should go to https://docs.pingcap.com/tidb/stable/sql-statement-alter-index.

[lilin90]

/lgtm

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-06-12 13:38:47.51751235 +0000 UTC m=+558281.570824274: ☑️ agreed by dveeden.
• 2024-06-13 10:30:20.252086716 +0000 UTC m=+633374.305398635: ☑️ agreed by lilin90.

[hfxsd]

/approve

[ti-chi-bot]

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #17891.