20.30.23 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table

The INNODB_FT_INDEX_CACHE table displays token information about newly inserted rows in a FULLTEXT index for an InnoDB table. To avoid expensive index reorganization during DML operations for an InnoDB FULLTEXT index, the information about newly indexed words is stored separately, and combined with the main search index only when you issue the OPTIMIZE TABLE statement for the InnoDB table.

This table is only accessible to users with the SUPER privilege. 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.

Table 20.22 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 in the FULLTEXT index.
LAST_DOC_IDThe last document ID that this word appears in in the FULLTEXT index.
DOC_COUNTThe number of rows this word appears in 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.

Notes: