Manual:Revision comment temp table

MediaWiki database layout

revision_comment_temp table

MediaWiki versions:

1.30 – 1.40

The revision_comment_temp table was a temporary table creating a relation between each row of the revision table and a row of the comment table. It was created (along with the similar revision_actor_temp table) to avoid blocking on an alter of the revision table, which took. On large wikis like the English Wikipedia, altering the revision table is a months-long process. This table was created so that other data migrations could be done while the alter was running. Once adding the rev_comment_id field to the revision table was done, the data from revision_comment_temp was merged back into the revision table and the table was deleted.

This table was introduced in Gerrit change 357892. See also the image_comment_temp table.

Fields

revcomment_rev

Key to revision.rev_id

revcomment_comment_id

Key to comment.comment_id

Schema summary

MediaWiki versions:

1.30 – 1.40

DESCRIBE revision_comment_temp;

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

Indexes

MediaWiki versions:

1.30 – 1.40

SHOW INDEX IN revision_comment_temp;

+-----------------------+------------+----------------+--------------+-----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| 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      |         |               |
+-----------------------+------------+----------------+--------------+-----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+