MediaWiki

Manual:comment table

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MediaWiki database layout
comment table
MediaWiki version:
≥ 1.30

The comment table stores edits, blocks, and other actions which typically have a textual comment describing the action. They are stored in a separate table to reduce the size of the main tables, and to allow for de-duplication.

De-duplication is currently best-effort to avoid locking on inserts that would be required for strict de-duplication. There may be multiple rows with the same comment_text and comment_data.

This table was introduced in Gerrit change 357892.

Fields

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comment_id

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Unique ID to identify each comment.

comment_hash

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Hash of comment_text and comment_data, for de-duplication. The current algorithm is a signed CRC32 of the comment text XOR'd with a CRC32 of any comment data.

comment_text

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Text comment summarizing the change, e.g. an editor's edit summary. This text is shown in the history and contributions . It is also used for recent changes , related changes , watchlists , and, in the case of page creation, for the list of new pages . It is rendered in a sanitized subset of wiki markup by MediaWiki\CommentFormatter\CommentFormatter::format(). Size limits are enforced at the application level, and should take care to crop UTF-8 strings appropriately.

comment_data

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JSON data, intended for localizing auto-generated comments. This holds structured data that is intended to be used to provide localized versions of automatically-generated comments. When not empty, comment_text should be the generated comment localized using the wiki's content language.

Schema

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MediaWiki version:
≥ 1.30

DESCRIBE comment; 

+--------------+---------------------+------+-----+---------+----------------+
| Field        | Type                | Null | Key | Default | Extra          |
+--------------+---------------------+------+-----+---------+----------------+
| comment_id   | bigint(20) unsigned | NO   | PRI | NULL    | auto_increment |
| comment_hash | int(11)             | NO   | MUL | NULL    |                |
| comment_text | blob                | NO   |     | NULL    |                |
| comment_data | blob                | YES  |     | NULL    |                |
+--------------+---------------------+------+-----+---------+----------------+

Indexes

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MediaWiki version:
≥ 1.30

SHOW INDEX IN comment; 

+---------+------------+--------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table   | Non_unique | Key_name     | Seq_in_index | Column_name  | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+--------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| comment |          0 | PRIMARY      |            1 | comment_id   | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| comment |          1 | comment_hash |            1 | comment_hash | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+---------+------------+--------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

Code stewardship

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See also

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