Manual:image_comment_temp table

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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 is being created to avoid such an alter, and will be merged back into the image table in the future.

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