Manual:Revision comment temp table

The revision_comment_temp table is a temporary table creating a relation between each row of the revision table and a row of the comment table. It has been created to avoid blocking on an alter of the revision table. On large wikis like the English Wikipedia, altering the revision table is a months-long process. This table is being created to avoid such an alter, and will be merged back into the revision table in the future.

This table was introduced in. See also the table.

revcomment_rev
Key to

revcomment_comment_id
Key to

Schema summary
+---+-+--+-+-+---+ +---+-+--+-+-+---+ +---+-+--+-+-+---+
 * Field                | Type                | Null | Key | Default | Extra |
 * revcomment_rev       | int(10) unsigned    | NO   | PRI | NULL    |       |
 * revcomment_comment_id | bigint(20) unsigned | NO  | PRI | NULL    |       |

Indexes
 +---+++--+---+---+-+--++--++-+---+ +---+++--+---+---+-+--++--++-+---+ +---+++--+---+---+-+--++--++-+---+
 * Table                | Non_unique | Key_name       | Seq_in_index | Column_name           | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
 * revision_comment_temp |         0 | PRIMARY        |            1 | revcomment_rev        | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
 * revision_comment_temp |         0 | PRIMARY        |            2 | revcomment_comment_id | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
 * revision_comment_temp |         0 | revcomment_rev |            1 | revcomment_rev        | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |