Manual:Change tag def table/de

The change_tag_def table is a table defining tag names for IDs. It also stores hit counts to avoid expensive queries on.

ctd_id
Numerical ID of the tag ( refers to this)

ctd_name
Symbolic name of the tag (what would previously be put in )

ctd_user_defined
Whether this tag was defined manually by a privileged user using Special:Tags

ctd_count
Number of times this tag was used

Schema summary
+--+-+--+-+-++ +--+-+--+-+-++ +--+-+--+-+-++
 * Field           | Type                | Null | Key | Default | Extra          |
 * ctd_id          | int(10) unsigned    | NO   | PRI | NULL    | auto_increment |
 * ctd_name        | varbinary(255)      | NO   | UNI | NULL    |                |
 * ctd_user_defined | tinyint(1)         | NO   | MUL | NULL    |                |
 * ctd_count       | bigint(20) unsigned | NO   | MUL | 0       |                |

Indexes
 +++--+--+--+---+-+--++--++-+---+ +++--+--+--+---+-+--++--++-+---+ +++--+--+--+---+-+--++--++-+---+
 * Table         | Non_unique | Key_name         | Seq_in_index | Column_name      | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
 * change_tag_def |         0 | PRIMARY          |            1 | ctd_id           | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
 * change_tag_def |         0 | ctd_name         |            1 | ctd_name         | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
 * change_tag_def |         1 | ctd_count        |            1 | ctd_count        | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
 * change_tag_def |         1 | ctd_user_defined |            1 | ctd_user_defined | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |