Indexes WHERE name LIKE ’test/%’; +----------+----------------------------------------------------+-------+ | table_id | name | space | +----------+----------------------------------------------------+-------+ | 333 | test/fts_0000000000000147_00000000000001c9_index_1 | 289 | | 334 | test/fts_0000000000000147_00000000000001c9_index_2 | 290 | | 335 | test/fts_0000000000000147_00000000000001c9_index_3 | 291 | | 336 | test/fts_0000000000000147_00000000000001c9_index_4 | 292 | | 337 | test/fts_0000000000000147_00000000000001c9_index_5 | 293 | | 338 | test/fts_0000000000000147_00000000000001c9_index_6 | 294 | | 330 | test/fts_0000000000000147_being_deleted | 286 | | 331 | test/fts_0000000000000147_being_deleted_cache | 287 | | 332 | test/fts_0000000000000147_config | 288 | | 328 | test/fts_0000000000000147_deleted | 284 | | 329 | test/fts_0000000000000147_deleted_cache | 285 | | 327 | test/opening_lines | 283 | +----------+----------------------------------------------------+-------+ The first six index tables comprise the inverted index and are referred to as auxiliary index tables. When incoming documents are tokenized, the individual words (also referred to as “tokens” ) are inserted into the index tables along with position information and an associated  DOC_ID . The words are fully sorted and partitioned among the six index tables based on the character set sort weight of the word’s first character. The inverted index is partitioned into six auxiliary index tables to support parallel index creation. By default, two threads tokenize, sort, and insert words and associated data into the index tables. The number of threads that perform this work is configurable using the  innodb_ft_sort_pll_degree  variable. Consider increasing the number of threads when creating full-text indexes on large tables. Auxiliary index table names are prefixed with  fts_  and postfixed with  index_ # . Each auxiliary index table is associated with the indexed table by a hex value in the auxiliary index table name that matches the table_id  of the indexed table. For example, the  table_id  of the  test/opening_lines  table is  327 , for which the hex value is 0x147. As shown in the preceding example, the “147”  hex value appears in the names of auxiliary index tables that are associated with the  test/opening_lines  table. A hex value representing the  index_id  of the full-text index also appears in auxiliary index table names. For example, in the auxiliary table name  test/ fts_0000000000000147_00000000000001c9_index_1 , the hex value  1c9  has a decimal value of 457. The index defined on the  opening_lines  table ( idx ) can be identified by querying the INFORMATION_SCHEMA.INNODB_INDEXES  table for this value (457). mysql>  SELECT index_id, name, table_id, space from INFORMATION_SCHEMA.INNODB_INDEXES WHERE index_id=457; +----------+------+----------+-------+ | index_id | name | table_id | space | +----------+------+----------+-------+ | 457 | idx | 327 | 283 | +----------+------+----------+-------+ Index tables are stored in their own tablespace if the primary table is created in a file-per-table tablespace. Otherwise, index tables are stored in the tablespace where the indexed table resides. The other index tables shown in the preceding example are referred to as common index tables and are used for deletion handling and storing the internal state of full-text indexes. Unlike the inverted index tables, which are created for each full-text index, this set of tables is common to all full-text indexes created on a particular table. Common index tables are retained even if full-text indexes are dropped. When a full-text index is dropped, the  FTS_DOC_ID  column that was created for the index is retained, as removing the  FTS_DOC_ID  column would require rebuilding the previously indexed table. Common index tables are required to manage the FTS_DOC_ID  column. 3045