Description:
During btree search on secondary index, when access primary index is necessary, row_sel_get_clust_rec_for_mysql() will be called. In this function, in some cases(old version/sec index entry has del mark) clust_rec and sec_rec will be compared to see if the index entry exists in the snapshot.
For virtual column, innobase_get_computed_value() will be called to construct the real row and compare with secondary record entry, but when the latter is on column's prefix, the compare(through cmp_data_data) will failed even if it should return success, hence the record can not be seen by the query.
How to repeat:
--connect(con1, localhost, root,,)
--connect(con2, localhost, root,,)
--connection con1
## Prepare data
CREATE TABLE t1 (
pk INT PRIMARY KEY AUTO_INCREMENT,
i INT,
vc VARCHAR(7),
gc1 VARCHAR(14) GENERATED ALWAYS AS (concat(vc, vc)) VIRTUAL NOT NULL,
gc2 VARCHAR(14) GENERATED ALWAYS AS (concat(gc1, 'x')) VIRTUAL NOT NULL,
KEY gc2_key (gc2),
KEY gc2_key_prefix (gc2(5))
);
INSERT INTO t1 (i, vc) VALUES
(7, 'xcek'), (3, 'ceksat'), (3, 'eksate'), (3, 'ksatef'), (6, 's');
--connection con1
--echo [connectionn con1]
BEGIN;
SELECT i FROM t1 FORCE INDEX (gc2_key_prefix) WHERE gc2 <= 'ksatefksatefx';
--connection con2
--echo [connectionn con2]
BEGIN;
SELECT i FROM t1 FORCE INDEX (gc2_key_prefix) WHERE gc2 <= 'ksatefksatefx';
--connection con1
--echo [connectionn con1]
## Delete records but not commit yet.
DELETE FROM t1;
--connection con2
--echo [connectionn con2]
## Query through virutal index return no result, but should see 3 records
SELECT i FROM t1 FORCE INDEX (gc2_key_prefix) WHERE gc2 <= 'ksatefksatefx';
## Query through PK see 3 records as expected
SELECT i FROM t1 FORCE INDEX (primary) WHERE gc2 <= 'ksatefksatefx';
