Bug：CHECK INDEX assert failure on tables with FULLTEXT index

Problem

Running CHECK INDEX on an InnoDB table with a FULLTEXT index triggers an assert failure.

Root Cause

In ha_innobase::check_index(), the loop only skips indexes with DICT_FTS type flag, but does not skip the hidden FTS_DOC_ID_INDEX — a regular B-tree index created internally by InnoDB for FTS document ID lookups. When check_index tries to get physical info for this index, it asserts.

Reproduce

CREATE TABLE fts_test (
id bigint NOT NULL,
tran_time varchar(20) NOT NULL,
body text,
PRIMARY KEY (id, tran_time),
FULLTEXT KEY (tran_time, body)
) ENGINE=InnoDB;

CHECK INDEX FROM fts_test; -- assert failure

Fix

Skip FTS_DOC_ID_INDEX in the loop and emit a warning, same as done for DICT_FTS indexes.

Parti dall’entry point ha_innobase::check_index() e confronta la gestione di DICT_FTS con quella di FTS_DOC_ID_INDEX nascosto. Riproduci i comandi CREATE TABLE e CHECK INDEX forniti, quindi verifica che il comando non generi più un’assertion ed emetta un avviso per l’indice ignorato.