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.

从 ha_innobase::check_index() 入口点开始，比较 DICT_FTS 与隐藏的 FTS_DOC_ID_INDEX 的处理方式。重现提供的 CREATE TABLE 和 CHECK INDEX 命令，然后确认该命令不再触发断言，并针对跳过的索引输出警告。