Manual:Image comment temp table

MediaWiki database layout

image_comment_temp table

MediaWiki versions:

1.30 – 1.31

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 task T188132. After that, the image_comment_temp table is removed.

Fields

imgcomment_name

Key to image.img_name

imgcomment_description_id

Key to comment.comment_id

Schema summary

MediaWiki versions:

1.30 – 1.31

DESCRIBE image_comment_temp;

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

Indexes

MediaWiki versions:

1.30 – 1.31

SHOW INDEX IN image_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      |         |               |
+--------------------+------------+-----------------+--------------+---------------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+