Manual:Comment table

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  and .

This table was introduced in .

comment_id
Unique ID to identify each comment.

comment_hash
Hash of  and , for de-duplication.

comment_text
Text comment summarizing the change, e.g. an editor's 1>m:Special:MyLanguage/Help:Edit summary|edit summary. This text is shown in the 1>m:Special:MyLanguage/Help:Page history|history and. It is also used for, , , and, in the case of page creation, for the. It is rendered in a sanitized subset of wiki markup by  . Size limits are enforced at the application level, and should take care to crop UTF-8 strings appropriately.

comment_data
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, <tvar|1></> should be the generated comment localized using the wiki's content language.

Schema
+--+-+--+-+-++ +--+-+--+-+-++ +--+-+--+-+-++
 * 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    |                |