Manual:image_comment_temp table

The image_comment_temp table is a temporary table creating a relation between each row of the image table and a row of the comment table. It has been created to avoid blocking on an alter of the image table. On large wikis like Wikimedia Commons, altering the image table is a months-long process. This table was created to avoid such an alter, and was merged back into the image table once the image.img_description_id field was created.

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

In MediaWiki 1.32, the image_comment_temp table is merged into the image table with T188132. After that, the image_comment_temp table is removed.

Key to image.img_name

Key to comment.comment_id

DESCRIBEimage_comment_temp;

+---------------------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------------------+---------------------+------+-----+---------+-------+
| imgcomment_name | varbinary(255) | NO | PRI | NULL | |
| imgcomment_description_id | bigint(20) unsigned | NO | PRI | NULL | |
+---------------------------+---------------------+------+-----+---------+-------+

SHOWINDEXINimage_comment_temp;

+--------------------+------------+-----------------+--------------+---------------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+--------------------+------------+-----------------+--------------+---------------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| image_comment_temp | 0 | PRIMARY | 1 | imgcomment_name | A | 0 | NULL | NULL | | BTREE | | |
| image_comment_temp | 0 | PRIMARY | 2 | imgcomment_description_id | A | 0 | NULL | NULL | | BTREE | | |
| image_comment_temp | 0 | imgcomment_name | 1 | imgcomment_name | A | 0 | NULL | NULL | | BTREE | | |
+--------------------+------------+-----------------+--------------+---------------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

• MediaWiki database tables