mariadb/mysql-test/suite/innodb/t/blob_cmp_empty.test
Vlad Lesin 3b10e8f80c MDEV-27746 Wrong comparision of BLOB's empty preffix with non-preffixed BLOB causes rows count mismatch for clustered and secondary indexes during non-locking read
row_sel_sec_rec_is_for_clust_rec() treats empty BLOB prefix field in
secondary index as a field equal to any external BLOB field in clustered
index. Row_sel_get_clust_rec_for_mysql::operator() doesn't zerro out
clustered record pointer in row_search_mvcc(), and row_search_mvcc()
thinks that delete-marked secondary index record has visible for
"CHECK TABLE"'s read view old-versioned clustered index record, and
row_scan_index_for_mysql() counts it as a row.

The fix is to execute row_sel_sec_rec_is_for_blob() in
row_sel_sec_rec_is_for_clust_rec() if clustered field contains BLOB's
reference.
2022-02-11 12:26:27 +03:00

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--source include/innodb_row_format.inc
--source include/count_sessions.inc
--connect(prevent_purge,localhost,root,,)
start transaction with consistent snapshot;
--connection default
SET @fill_amount = (@@innodb_page_size / 2 ) + 1;
CREATE TABLE t1 (col_text TEXT NOT NULL, KEY (col_text(9))) ENGINE=InnoDB;
INSERT INTO t1 (col_text) VALUES (REPEAT('x', @fill_amount));
UPDATE t1 SET col_text='';
UPDATE t1 SET col_text=REPEAT('y', @fill_amount);
--connect(con1,localhost,root,,)
SET @fill_amount = (@@innodb_page_size / 2 ) + 1;
BEGIN;
INSERT INTO t1 (col_text) VALUES (REPEAT('z', @fill_amount));
--connection default
# If the bug is not fixed, CHECK TABLE will complain about wrong secondary index
# rows count
CHECK TABLE t1;
--disconnect con1
--disconnect prevent_purge
DROP TABLE t1;
--source include/wait_until_count_sessions.inc