28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table

The INNODB_FT_INDEX_TABLE table provides information about the inverted index used to process text searches against the FULLTEXT index of an InnoDB table.

This table is empty initially. Before querying it, set the value of the innodb_ft_aux_table system variable 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 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables”.

The INNODB_FT_INDEX_TABLE table has these columns:

• WORD

  A word extracted from the text of the columns that are part of a FULLTEXT.

• FIRST_DOC_ID

  The first document ID in which this word appears in the FULLTEXT index.

• LAST_DOC_ID

  The last document ID in which this word appears in the FULLTEXT index.

• DOC_COUNT

  The number of rows in which 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_ID

  The document ID of the row containing the word. 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 contains no suitable column.

• POSITION

  The position of this particular instance of the word within the relevant document identified by the DOC_ID value.

Notes

• This table is empty initially. Before querying it, set the value of the innodb_ft_aux_table system variable to the name (including the database name) of the table that contains the FULLTEXT index (for example, test/articles). The following example demonstrates how to use the innodb_ft_aux_table system variable to show information about a FULLTEXT index for a specified table. Before information for newly inserted rows appears in INNODB_FT_INDEX_TABLE, the FULLTEXT index cache must be flushed to disk. This is accomplished by running an OPTIMIZE TABLE operation on the indexed table with the innodb_optimize_fulltext_only system variable enabled. (The example disables that variable again at the end because it is intended to be enabled only temporarily.)

  mysql> USE test;
  
  mysql> CREATE TABLE articles (
           id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
           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 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_optimize_fulltext_only=ON;
  
  mysql> OPTIMIZE TABLE articles;
  +---------------+----------+----------+----------+
  | Table         | Op       | Msg_type | Msg_text |
  +---------------+----------+----------+----------+
  | test.articles | optimize | status   | OK       |
  +---------------+----------+----------+----------+
  
  mysql> SET GLOBAL innodb_ft_aux_table = 'test/articles';
  
  mysql> SELECT WORD, DOC_COUNT, DOC_ID, POSITION
         FROM INFORMATION_SCHEMA.INNODB_FT_INDEX_TABLE 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 |
  +------------+-----------+--------+----------+
  
  mysql> SET GLOBAL innodb_optimize_fulltext_only=OFF;

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

• Use the INFORMATION_SCHEMA COLUMNS table or the SHOW COLUMNS statement to view additional information about the columns of this table, including data types and default values.

• For more information about InnoDB FULLTEXT search, see Section 17.6.2.4, “InnoDB Full-Text Indexes”, and Section 14.9, “Full-Text Search Functions”.