手册:categorylinks表

From mediawiki.org
This page is a translated version of the page Manual:Categorylinks table and the translation is 35% complete.
手册:索引 MediaWiki数据库布局 categorylinks表
MediaWiki版本:
1.3

categorylinks表存储与[[Category:Title]][[Category:Title|sortkey]]形式的链接相对应的条目,当将其放置在页面上的任何位置时,该页面会将该页面放入名为的分类中“标题”(其关联页面可能存在,也可能不存在)。 以冒号开头的链接,如[[:Category:Title]],不会存储在categorylinks表中,而是按正常的内部链接处理(在本例中指向页面 Category:Title)。 The editable parts of category pages are stored like other pages.

There are four indexes which help improve performance:

  • The concatenation of cl_from and cl_to (for when an article is edited)
  • The concatenation of cl_to, cl_type, cl_sortkey, and cl_from (for showing articles in order)
  • The concatenation of cl_to and cl_timestamp
  • cl_collation

字段

cl_from

Stores the page.page_id of the article where the link was placed.

cl_to

Stores the name of the desired category in the page_title format (that is, with _ and excluding namespace prefix).

cl_sortkey

Stores the title by which the page should be sorted in a category list. This is the binary sortkey, that depending on $wgCategoryCollation may or may not be readable by a human (but should sort in correct order when comparing as a byte string), and is not valid UTF-8 whenever the database truncates the sortkey in the middle of a multi-byte sequence.

cl_timestamp

Stores the time at which that link was last updated in the table.

cl_sortkey_prefix

This is either the empty string if a page is using the default sortkey (aka the sortkey is unspecified). Otherwise it is the human readable version of cl_sortkey. Needed mostly so that cl_sortkey can be easily updated in certain situations without re-parsing the entire page. More recently added values are valid UTF-8 (see change 449280 on Gerrit).

cl_collation

MediaWiki版本:
1.17

What collation is in use. Used so that if the collation changes, the updateCollation.php script knows what rows need to be fixed in db.

cl_type

What type of page is this (file, subcat (subcategory) or page (normal page)). Used so that the different sections on a category page can be paged independently in an efficient manner.

Schema summary

MediaWiki版本:
1.17

DESCRIBE categorylinks;

+-------------------+------------------------------+------+-----+-------------------+-----------------------------+
| Field             | Type                         | Null | Key | Default           | Extra                       |
+-------------------+------------------------------+------+-----+-------------------+-----------------------------+
| cl_from           | int(10) unsigned             | NO   | PRI | 0                 |                             |
| cl_to             | varbinary(255)               | NO   | PRI |                   |                             |
| cl_sortkey        | varbinary(230)               | NO   |     |                   |                             |
| cl_sortkey_prefix | varbinary(255)               | NO   |     |                   |                             |
| cl_timestamp      | timestamp                    | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| cl_collation      | varbinary(32)                | NO   | MUL |                   |                             |
| cl_type           | enum('page','subcat','file') | NO   |     | page              |                             |
+-------------------+------------------------------+------+-----+-------------------+-----------------------------+
警告 警告: Starting with version 1.17, the index on (cl_to, cl_sortkey) is no more, and replaced with one on (cl_to, cl_type, cl_sortkey, cl_from). Extensions that directly query the categorylinks table to get a list of pages in sorted order need to make sure they are using the new index, or the query may become very inefficient
MediaWiki版本:
1.10 – 1.16

DESCRIBE categorylinks;

+--------------+------------------+------+-----+-------------------+-----------------------------+
| Field        | Type             | Null | Key | Default           | Extra                       |
+--------------+------------------+------+-----+-------------------+-----------------------------+
| cl_from      | int(10) unsigned | NO   | PRI | 0                 |                             |
| cl_to        | varbinary(255)   | NO   | PRI |                   |                             |
| cl_sortkey   | varbinary(70)    | NO   |     |                   |                             |
| cl_timestamp | timestamp        | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+--------------+------------------+------+-----+-------------------+-----------------------------+
MediaWiki版本:
1.5 – 1.9

DESCRIBE categorylinks;

+--------------+-----------------+------+-----+-------------------+-----------------------------+
| Field        | Type            | Null | Key | Default           | Extra                       |
+--------------+-----------------+------+-----+-------------------+-----------------------------+
| cl_from      | int(8) unsigned | NO   | PRI | 0                 |                             |
| cl_to        | varchar(255)    | NO   | PRI |                   |                             |
| cl_sortkey   | varchar(86)     | NO   |     |                   |                             |
| cl_timestamp | timestamp       | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+--------------+-----------------+------+-----+-------------------+-----------------------------+
MediaWiki版本:
1.3 – 1.4

DESCRIBE categorylinks;

+--------------+-----------------+------+-----+-------------------+-----------------------------+
| Field        | Type            | Null | Key | Default           | Extra                       |
+--------------+-----------------+------+-----+-------------------+-----------------------------+
| cl_from      | int(8) unsigned | NO   | PRI | 0                 |                             |
| cl_to        | varchar(255)    | NO   | PRI |                   |                             |
| cl_sortkey   | varchar(255)    | NO   |     |                   |                             |
| cl_timestamp | timestamp       | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+--------------+-----------------+------+-----+-------------------+-----------------------------+

索引

MediaWiki版本:
1.42

SHOW INDEX IN categorylinks;

+---------------+------------+--------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table         | Non_unique | Key_name     | Seq_in_index | Column_name  | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------+------------+--------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| categorylinks |          0 | PRIMARY      |            1 | cl_from      | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| categorylinks |          0 | PRIMARY      |            2 | cl_to        | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| categorylinks |          1 | cl_sortkey   |            1 | cl_to        | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| categorylinks |          1 | cl_sortkey   |            2 | cl_type      | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| categorylinks |          1 | cl_sortkey   |            3 | cl_sortkey   | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| categorylinks |          1 | cl_sortkey   |            4 | cl_from      | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| categorylinks |          1 | cl_timestamp |            1 | cl_to        | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| categorylinks |          1 | cl_timestamp |            2 | cl_timestamp | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+---------------+------------+--------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

参见

外部链接