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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

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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.
This commit is contained in:
Vlad Lesin
2022-02-09 16:50:28 +03:00
parent 3a52569499
commit 3b10e8f80c
3 changed files with 52 additions and 1 deletions
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19
mysql-test/suite/innodb/r/blob_cmp_empty.result Normal file
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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;
CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
disconnect con1;
disconnect prevent_purge;
DROP TABLE t1;