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MySQL 5.7 Reference Manual  /  ...  /  The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table


INNODB_FT_INDEX_CACHE: Contains token information about newly inserted rows in a FULLTEXT index. To avoid expensive index reorganization during DML operations, the information about newly indexed words is stored separately, and combined with the main search index only when OPTIMIZE TABLE is run, when the server is shut down, or when the cache size exceeds a limit defined by innodb_ft_cache_size or innodb_ft_total_cache_size.

Before you query this table, set the configuration variable innodb_ft_aux_table to the name (including the database name) of the table that contains the FULLTEXT index, for example test/articles.

For related usage information and examples, see Section 14.12.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables”.

Table 20.26 INNODB_FT_INDEX_CACHE Columns

Column nameDescription
WORDA word extracted from the text of a newly inserted row.
FIRST_DOC_IDThe first document ID that this word appears in the FULLTEXT index.
LAST_DOC_IDThe last document ID that this word appears in the FULLTEXT index.
DOC_COUNTThe number of rows this word appears in the FULLTEXT index. The same word can occur several times within the cache table, once for each combination of DOC_ID and POSITION values.
DOC_IDThe document ID of the newly inserted row. This value might reflect the value of an ID column that you defined for the underlying table, or it can be a sequence value generated by InnoDB when the table does not contain a suitable column.
POSITIONThe position of this particular instance of the word within the relevant document identified by the DOC_ID value. The value does not represent an absolute position; it is an offset added to the POSITION of the previous instance of that word.


  • This table initially appears empty, until you set the value of the configuration variable innodb_ft_aux_table. The following example demonstrates how to use the innodb_ft_aux_table option to show information about a FULLTEXT index for a specified table.

    mysql> USE test;
    mysql> CREATE TABLE articles (
          title VARCHAR(200),
          body TEXT,
          FULLTEXT (title,body)
        ) ENGINE=InnoDB;
    mysql> INSERT INTO articles (title,body) VALUES
        ('MySQL Tutorial','DBMS stands for DataBase ...'),
        ('How To Use MySQL Well','After you went through a ...'),
        ('Optimizing MySQL','In this tutorial we will show ...'),
        ('1001 MySQL Tricks','1. Never run mysqld as root. 2. ...'),
        ('MySQL vs. YourSQL','In the following database comparison ...'),
        ('MySQL Security','When configured properly, MySQL ...');
    mysql> SET GLOBAL innodb_ft_aux_table = 'test/articles';
    Query OK, 0 rows affected (0.00 sec)
    mysql> SELECT word, doc_count, doc_id, position FROM INNODB_FT_INDEX_CACHE LIMIT 5;
    | word       | doc_count | doc_id | position |
    | 1001       |         1 |      4 |        0 |
    | after      |         1 |      2 |       22 |
    | comparison |         1 |      5 |       44 |
    | configured |         1 |      6 |       20 |
    | database   |         2 |      1 |       31 |
  • Use DESCRIBE or SHOW COLUMNS to view additional information about the columns of this table including data types and default values.

  • You must have the PROCESS privilege to query this table.

  • For more information about InnoDB FULLTEXT search, see Section, “InnoDB FULLTEXT Indexes”, and Section 12.9, “Full-Text Search Functions”.

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