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drop view if exists v1; drop table if exists t1,t4; create table t4 ( pk_col int auto_increment primary key, a1 char(64), a2 char(64), b char(16), c char(16) not null, d char(16), dummy char(64) default ' ' ) engine=innodb; insert into t4 (a1, a2, b, c, d) values ('a','a','a','a111','xy1'),('a','a','a','b111','xy2'),('a','a','a','c111','xy3'),('a','a','a','d111','xy4'), ('a','a','b','e112','xy1'),('a','a','b','f112','xy2'),('a','a','b','g112','xy3'),('a','a','b','h112','xy4'), ('a','b','a','i121','xy1'),('a','b','a','j121','xy2'),('a','b','a','k121','xy3'),('a','b','a','l121','xy4'), ('a','b','b','m122','xy1'),('a','b','b','n122','xy2'),('a','b','b','o122','xy3'),('a','b','b','p122','xy4'), ('b','a','a','a211','xy1'),('b','a','a','b211','xy2'),('b','a','a','c211','xy3'),('b','a','a','d211','xy4'), ('b','a','b','e212','xy1'),('b','a','b','f212','xy2'),('b','a','b','g212','xy3'),('b','a','b','h212','xy4'), ('b','b','a','i221','xy1'),('b','b','a','j221','xy2'),('b','b','a','k221','xy3'),('b','b','a','l221','xy4'), ('b','b','b','m222','xy1'),('b','b','b','n222','xy2'),('b','b','b','o222','xy3'),('b','b','b','p222','xy4'), ('c','a','a','a311','xy1'),('c','a','a','b311','xy2'),('c','a','a','c311','xy3'),('c','a','a','d311','xy4'), ('c','a','b','e312','xy1'),('c','a','b','f312','xy2'),('c','a','b','g312','xy3'),('c','a','b','h312','xy4'), ('c','b','a','i321','xy1'),('c','b','a','j321','xy2'),('c','b','a','k321','xy3'),('c','b','a','l321','xy4'), ('c','b','b','m322','xy1'),('c','b','b','n322','xy2'),('c','b','b','o322','xy3'),('c','b','b','p322','xy4'), ('d','a','a','a411','xy1'),('d','a','a','b411','xy2'),('d','a','a','c411','xy3'),('d','a','a','d411','xy4'), ('d','a','b','e412','xy1'),('d','a','b','f412','xy2'),('d','a','b','g412','xy3'),('d','a','b','h412','xy4'), ('d','b','a','i421','xy1'),('d','b','a','j421','xy2'),('d','b','a','k421','xy3'),('d','b','a','l421','xy4'), ('d','b','b','m422','xy1'),('d','b','b','n422','xy2'),('d','b','b','o422','xy3'),('d','b','b','p422','xy4'), ('a','a','a','a111','xy1'),('a','a','a','b111','xy2'),('a','a','a','c111','xy3'),('a','a','a','d111','xy4'), ('a','a','b','e112','xy1'),('a','a','b','f112','xy2'),('a','a','b','g112','xy3'),('a','a','b','h112','xy4'), ('a','b','a','i121','xy1'),('a','b','a','j121','xy2'),('a','b','a','k121','xy3'),('a','b','a','l121','xy4'), ('a','b','b','m122','xy1'),('a','b','b','n122','xy2'),('a','b','b','o122','xy3'),('a','b','b','p122','xy4'), ('b','a','a','a211','xy1'),('b','a','a','b211','xy2'),('b','a','a','c211','xy3'),('b','a','a','d211','xy4'), ('b','a','b','e212','xy1'),('b','a','b','f212','xy2'),('b','a','b','g212','xy3'),('b','a','b','h212','xy4'), ('b','b','a','i221','xy1'),('b','b','a','j221','xy2'),('b','b','a','k221','xy3'),('b','b','a','l221','xy4'), ('b','b','b','m222','xy1'),('b','b','b','n222','xy2'),('b','b','b','o222','xy3'),('b','b','b','p222','xy4'), ('c','a','a','a311','xy1'),('c','a','a','b311','xy2'),('c','a','a','c311','xy3'),('c','a','a','d311','xy4'), ('c','a','b','e312','xy1'),('c','a','b','f312','xy2'),('c','a','b','g312','xy3'),('c','a','b','h312','xy4'), ('c','b','a','i321','xy1'),('c','b','a','j321','xy2'),('c','b','a','k321','xy3'),('c','b','a','l321','xy4'), ('c','b','b','m322','xy1'),('c','b','b','n322','xy2'),('c','b','b','o322','xy3'),('c','b','b','p322','xy4'), ('d','a','a','a411','xy1'),('d','a','a','b411','xy2'),('d','a','a','c411','xy3'),('d','a','a','d411','xy4'), ('d','a','b','e412','xy1'),('d','a','b','f412','xy2'),('d','a','b','g412','xy3'),('d','a','b','h412','xy4'), ('d','b','a','i421','xy1'),('d','b','a','j421','xy2'),('d','b','a','k421','xy3'),('d','b','a','l421','xy4'), ('d','b','b','m422','xy1'),('d','b','b','n422','xy2'),('d','b','b','o422','xy3'),('d','b','b','p422','xy4'); create index idx12672_0 on t4 (a1); create index idx12672_1 on t4 (a1,a2,b,c); create index idx12672_2 on t4 (a1,a2,b); analyze table t4; Table Op Msg_type Msg_text test.t4 analyze status OK select distinct a1 from t4 where pk_col not in (1,2,3,4); a1 a b c d drop table t4; create table t1 ( a varchar(30), b varchar(30), primary key(a), key(b) ) engine=innodb; select distinct a from t1; a drop table t1; create table t1(a int, key(a)) engine=innodb; insert into t1 values(1); select a, count(a) from t1 group by a with rollup; a count(a) 1 1 NULL 1 drop table t1; create table t1 (f1 int, f2 char(1), primary key(f1,f2)) engine=innodb stats_persistent=0; insert into t1 values ( 1,"e"),(2,"a"),( 3,"c"),(4,"d"); alter table t1 drop primary key, add primary key (f2, f1); explain select distinct f1 a, f1 b from t1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index PRIMARY PRIMARY 5 NULL 4 Using index; Using temporary explain select distinct f1, f2 from t1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index PRIMARY PRIMARY 5 NULL 4 Using index drop table t1; create table t1(pk int primary key) engine=innodb; create view v1 as select pk from t1 where pk < 20; insert into t1 values (1), (2), (3), (4); select distinct pk from v1; pk 1 2 3 4 insert into t1 values (5), (6), (7); select distinct pk from v1; pk 1 2 3 4 5 6 7 drop view v1; drop table t1; End of 5.1 tests # # Bug#12540545 61101: ASSERTION FAILURE IN THREAD 1256741184 IN # FILE /BUILDDIR/BUILD/BUILD/MYSQ # CREATE TABLE t1 (a CHAR(1), b CHAR(1), PRIMARY KEY (a,b)) ENGINE=InnoDB; INSERT INTO t1 VALUES ('a', 'b'), ('c', 'd'); EXPLAIN SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index PRIMARY PRIMARY 2 NULL 2 Using where; Using index SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; COUNT(DISTINCT a) 1 DROP TABLE t1; CREATE TABLE t1 (a CHAR(1) NOT NULL, b CHAR(1) NOT NULL, UNIQUE KEY (a,b)) ENGINE=InnoDB; INSERT INTO t1 VALUES ('a', 'b'), ('c', 'd'); EXPLAIN SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index a a 2 NULL 2 Using where; Using index SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; COUNT(DISTINCT a) 1 DROP TABLE t1; End of 5.5 tests # # Bug#17909656 - WRONG RESULTS FOR A SIMPLE QUERY WITH GROUP BY # CREATE TABLE t0 ( i1 INTEGER NOT NULL ); INSERT INTO t0 VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(10), (11),(12),(13),(14),(15),(16),(17),(18),(19),(20), (21),(22),(23),(24),(25),(26),(27),(28),(29),(30); CREATE TABLE t1 ( c1 CHAR(1) NOT NULL, i1 INTEGER NOT NULL, i2 INTEGER NOT NULL, UNIQUE KEY k1 (c1,i2) ) ENGINE=InnoDB; INSERT INTO t1 SELECT 'A',i1,i1 FROM t0; INSERT INTO t1 SELECT 'B',i1,i1 FROM t0; INSERT INTO t1 SELECT 'C',i1,i1 FROM t0; INSERT INTO t1 SELECT 'D',i1,i1 FROM t0; INSERT INTO t1 SELECT 'E',i1,i1 FROM t0; INSERT INTO t1 SELECT 'F',i1,i1 FROM t0; CREATE TABLE t2 ( c1 CHAR(1) NOT NULL, i1 INTEGER NOT NULL, i2 INTEGER NOT NULL, UNIQUE KEY k2 (c1,i1,i2) ) ENGINE=InnoDB; INSERT INTO t2 SELECT 'A',i1,i1 FROM t0; INSERT INTO t2 SELECT 'B',i1,i1 FROM t0; INSERT INTO t2 SELECT 'C',i1,i1 FROM t0; INSERT INTO t2 SELECT 'D',i1,i1 FROM t0; INSERT INTO t2 SELECT 'E',i1,i1 FROM t0; INSERT INTO t2 SELECT 'F',i1,i1 FROM t0; ANALYZE TABLE t1; ANALYZE TABLE t2; set optimizer_trace_max_mem_size=1048576; set @@session.optimizer_trace='enabled=on'; set end_markers_in_json=on; EXPLAIN SELECT c1, max(i2) FROM t1 WHERE (c1 = 'C' AND i2 = 17) OR ( c1 = 'F') GROUP BY c1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range k1 k1 5 NULL ROWS Using where; Using index SELECT c1, max(i2) FROM t1 WHERE (c1 = 'C' AND i2 = 17) OR ( c1 = 'F') GROUP BY c1; c1 max(i2) C 17 F 30 SELECT TRACE RLIKE 'minmax_keypart_in_disjunctive_query' AS OK FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; OK 1 EXPLAIN SELECT c1, max(i2) FROM t1 WHERE (c1 = 'C' OR ( c1 = 'F' AND i2 = 17)) GROUP BY c1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range k1 k1 5 NULL ROWS Using where; Using index SELECT c1, max(i2) FROM t1 WHERE (c1 = 'C' OR ( c1 = 'F' AND i2 = 17)) GROUP BY c1; c1 max(i2) C 30 F 17 SELECT TRACE RLIKE 'minmax_keypart_in_disjunctive_query' AS OK FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; OK 1 EXPLAIN SELECT c1, max(i2) FROM t1 WHERE (c1 = 'C' OR c1 = 'F' ) AND ( i2 = 17 ) GROUP BY c1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range k1 k1 5 NULL ROWS Using where; Using index for group-by SELECT c1, max(i2) FROM t1 WHERE (c1 = 'C' OR c1 = 'F' ) AND ( i2 = 17 ) GROUP BY c1; c1 max(i2) C 17 F 17 SELECT TRACE RLIKE 'minmax_keypart_in_disjunctive_query' AS OK FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; OK 0 EXPLAIN SELECT c1, max(i2) FROM t1 WHERE ((c1 = 'C' AND (i2 = 40 OR i2 = 30)) OR ( c1 = 'F' AND (i2 = 40 ))) GROUP BY c1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range k1 k1 5 NULL ROWS Using where; Using index SELECT c1, max(i2) FROM t1 WHERE ((c1 = 'C' AND (i2 = 40 OR i2 = 30)) OR ( c1 = 'F' AND (i2 = 40 ))) GROUP BY c1; c1 max(i2) C 30 SELECT TRACE RLIKE 'minmax_keypart_in_disjunctive_query' AS OK FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; OK 1 EXPLAIN SELECT c1, i1, max(i2) FROM t2 WHERE (c1 = 'C' OR ( c1 = 'F' AND i1 < 35)) AND ( i2 = 17 ) GROUP BY c1,i1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range k2 k2 5 NULL ROWS Using where; Using index SELECT c1, i1, max(i2) FROM t2 WHERE (c1 = 'C' OR ( c1 = 'F' AND i1 < 35)) AND ( i2 = 17 ) GROUP BY c1,i1; c1 i1 max(i2) C 17 17 F 17 17 SELECT TRACE RLIKE 'minmax_keypart_in_disjunctive_query' AS OK FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; OK 0 EXPLAIN SELECT c1, i1, max(i2) FROM t2 WHERE (((c1 = 'C' AND i1 < 40) OR ( c1 = 'F' AND i1 < 35)) AND ( i2 = 17 )) GROUP BY c1,i1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range k2 k2 5 NULL ROWS Using where; Using index SELECT c1, i1, max(i2) FROM t2 WHERE (((c1 = 'C' AND i1 < 40) OR ( c1 = 'F' AND i1 < 35)) AND ( i2 = 17 )) GROUP BY c1,i1; c1 i1 max(i2) C 17 17 F 17 17 SELECT TRACE RLIKE 'minmax_keypart_in_disjunctive_query' AS OK FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; OK 0 EXPLAIN SELECT c1, i1, max(i2) FROM t2 WHERE ((c1 = 'C' AND i1 < 40) OR ( c1 = 'F' AND i1 < 35) OR ( i2 = 17 )) GROUP BY c1,i1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 index k2 k2 9 NULL ROWS Using where; Using index SELECT c1, i1, max(i2) FROM t2 WHERE ((c1 = 'C' AND i1 < 40) OR ( c1 = 'F' AND i1 < 35) OR ( i2 = 17 )) GROUP BY c1,i1; c1 i1 max(i2) A 17 17 B 17 17 C 1 1 C 2 2 C 3 3 C 4 4 C 5 5 C 6 6 C 7 7 C 8 8 C 9 9 C 10 10 C 11 11 C 12 12 C 13 13 C 14 14 C 15 15 C 16 16 C 17 17 C 18 18 C 19 19 C 20 20 C 21 21 C 22 22 C 23 23 C 24 24 C 25 25 C 26 26 C 27 27 C 28 28 C 29 29 C 30 30 D 17 17 E 17 17 F 1 1 F 2 2 F 3 3 F 4 4 F 5 5 F 6 6 F 7 7 F 8 8 F 9 9 F 10 10 F 11 11 F 12 12 F 13 13 F 14 14 F 15 15 F 16 16 F 17 17 F 18 18 F 19 19 F 20 20 F 21 21 F 22 22 F 23 23 F 24 24 F 25 25 F 26 26 F 27 27 F 28 28 F 29 29 F 30 30 SELECT TRACE RLIKE 'minmax_keypart_in_disjunctive_query' AS OK FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; OK 0 SET optimizer_trace_max_mem_size=DEFAULT; SET optimizer_trace=DEFAULT; SET end_markers_in_json=DEFAULT; DROP TABLE t0,t1,t2; # # Bug #21749123: SELECT DISTINCT, WRONG RESULTS COMBINED WITH # USE_INDEX_EXTENSIONS=OFF # CREATE TABLE t1 ( pk_col INT AUTO_INCREMENT PRIMARY KEY, a1 CHAR(64), KEY a1_idx (a1) ) ENGINE=INNODB; INSERT INTO t1 (a1) VALUES ('a'),('a'),('a'),('a'),('a'),('a'),('a'),('a'); CREATE TABLE t2 ( pk_col1 INT NOT NULL, pk_col2 INT NOT NULL, a1 CHAR(64), a2 CHAR(64), PRIMARY KEY(pk_col1, pk_col2), KEY a1_idx (a1), KEY a1_a2_idx (a1, a2) ) ENGINE=INNODB; INSERT INTO t2 (pk_col1, pk_col2, a1, a2) VALUES (1,1,'a','b'),(1,2,'a','b'), (1,3,'a','c'),(1,4,'a','c'), (2,1,'a','d'); ANALYZE TABLE t1; Table Op Msg_type Msg_text test.t1 analyze status OK ANALYZE TABLE t2; Table Op Msg_type Msg_text test.t2 analyze status OK EXPLAIN SELECT DISTINCT a1 FROM t1 WHERE (pk_col = 2 OR pk_col = 22) AND a1 = 'a'; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref PRIMARY,a1_idx a1_idx 65 const 4 Using where; Using index SELECT DISTINCT a1 FROM t1 WHERE (pk_col = 2 OR pk_col = 22) AND a1 = 'a'; a1 a EXPLAIN SELECT COUNT(DISTINCT a1) FROM t1 GROUP BY a1,pk_col; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range a1_idx a1_idx 69 NULL 9 Using index for group-by (scanning) SELECT COUNT(DISTINCT a1) FROM t1 GROUP BY a1,pk_col; COUNT(DISTINCT a1) 1 1 1 1 1 1 1 1 EXPLAIN SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,pk_col1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range a1_idx,a1_a2_idx a1_idx 69 NULL 6 Using index for group-by (scanning) SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,pk_col1; COUNT(DISTINCT a1) 1 1 EXPLAIN SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,a2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range a1_a2_idx a1_a2_idx 130 NULL 6 Using index for group-by (scanning) SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,a2; COUNT(DISTINCT a1) 1 1 1 SET @optimizer_switch_save=@@optimizer_switch; SET @@optimizer_switch= "use_index_extensions=off"; EXPLAIN SELECT DISTINCT a1 FROM t1 WHERE (pk_col = 2 OR pk_col = 22) AND a1 = 'a'; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref PRIMARY,a1_idx a1_idx 65 const 8 Using where; Using index SELECT DISTINCT a1 FROM t1 WHERE (pk_col = 2 OR pk_col = 22) AND a1 = 'a'; a1 a EXPLAIN SELECT COUNT(DISTINCT a1) FROM t1 GROUP BY a1,pk_col; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index a1_idx a1_idx 65 NULL 8 Using index SELECT COUNT(DISTINCT a1) FROM t1 GROUP BY a1,pk_col; COUNT(DISTINCT a1) 1 1 1 1 1 1 1 1 EXPLAIN SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,pk_col1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 index a1_idx,a1_a2_idx a1_idx 65 NULL 5 Using index SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,pk_col1; COUNT(DISTINCT a1) 1 1 EXPLAIN SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,a2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range a1_a2_idx a1_a2_idx 130 NULL 6 Using index for group-by (scanning) SELECT COUNT(DISTINCT a1) FROM t2 GROUP BY a1,a2; COUNT(DISTINCT a1) 1 1 1 SET @@optimizer_switch= @optimizer_switch_save; DROP TABLE t1, t2; # # Bug #24671968: WHEN THE OPTIMISER IS USING INDEX FOR GROUP-BY IT OFTEN # OFTEN GIVES WRONG RESULTS # CREATE TABLE t1 ( id int NOT NULL, c1 int NOT NULL, c2 int, PRIMARY KEY(id), INDEX c1_c2_idx(c1, c2)); INSERT INTO t1 (id, c1, c2) VALUES (1,1,1), (2,2,2), (10,10,1), (11,10,8), (12,10,1), (13,10,2), (3,1,1), (4,10,1), (5,10,1), (6,10,8), (7,1,1), (8,10,1); ANALYZE TABLE t1; Table Op Msg_type Msg_text test.t1 analyze status OK EXPLAIN SELECT DISTINCT c1 FROM t1 WHERE EXISTS (SELECT * FROM DUAL WHERE (c2 = 2)); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index c1_c2_idx c1_c2_idx 9 NULL # Using where; Using index 2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL # No tables used EXPLAIN SELECT DISTINCT c1 FROM t1 WHERE 1 IN (2, (SELECT 1 FROM DUAL WHERE (c2 = 2)), 3); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index c1_c2_idx c1_c2_idx 9 NULL # Using where; Using index 2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL # No tables used EXPLAIN SELECT DISTINCT c1 FROM t1 WHERE c2 = 2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range c1_c2_idx c1_c2_idx 9 NULL # Using where; Using index for group-by EXPLAIN SELECT DISTINCT c1 FROM t1 IGNORE INDEX (c1_c2_idx) WHERE EXISTS (SELECT * FROM DUAL WHERE (c2 = 2)); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL c1_c2_idx NULL NULL NULL # Using where; Using temporary 2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL # No tables used EXPLAIN SELECT DISTINCT c1 FROM t1 IGNORE INDEX (c1_c2_idx) WHERE 1 IN (2, (SELECT 1 FROM DUAL WHERE (c2 = 2)), 3); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL c1_c2_idx NULL NULL NULL # Using where; Using temporary 2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL # No tables used SET optimizer_trace="enabled=on"; SELECT DISTINCT c1 FROM t1 WHERE EXISTS (SELECT * FROM DUAL WHERE (c2 = 2)); c1 2 10 SELECT TRACE INTO @trace FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; SELECT @trace RLIKE "keypart_reference_from_where_clause"; @trace RLIKE "keypart_reference_from_where_clause" 1 SET optimizer_trace="enabled=off"; SELECT DISTINCT c1 FROM t1 WHERE 1 IN (2, (SELECT 1 FROM DUAL WHERE (c2 = 2)), 3); c1 2 10 SELECT DISTINCT c1 FROM t1 WHERE c2 = 2; c1 2 10 SELECT DISTINCT c1 FROM t1 IGNORE INDEX (c1_c2_idx) WHERE EXISTS (SELECT * FROM DUAL WHERE (c2 = 2)); c1 2 10 SELECT DISTINCT c1 FROM t1 IGNORE INDEX (c1_c2_idx) WHERE 1 IN (2, (SELECT 1 FROM DUAL WHERE (c2 = 2)), 3); c1 2 10 DROP TABLE t1; # # Bug #25989915: LOOSE INDEX SCANS RETURNING WRONG RESULT # CREATE TABLE t1 ( pk INT NOT NULL AUTO_INCREMENT, c1 varchar(100) DEFAULT NULL, c2 INT NOT NULL, PRIMARY KEY (pk), UNIQUE KEY ukey (c2,c1) )ENGINE=INNODB; INSERT INTO t1(pk, c2) VALUES (100, 0), (101, 0), (102, 0), (103, 0); ANALYZE TABLE t1; Table Op Msg_type Msg_text test.t1 analyze status OK EXPLAIN SELECT COUNT(DISTINCT(c2)) FROM t1 WHERE pk IN (102, 101); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index PRIMARY,ukey ukey 107 NULL 4 Using where; Using index EXPLAIN SELECT COUNT(DISTINCT(c2)) FROM t1 WHERE pk IN (102, 100); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index PRIMARY,ukey ukey 107 NULL 4 Using where; Using index SELECT COUNT(DISTINCT(c2)) FROM t1 WHERE pk IN (102, 101); COUNT(DISTINCT(c2)) 1 SELECT COUNT(DISTINCT(c2)) FROM t1 WHERE pk IN (102, 100); COUNT(DISTINCT(c2)) 1 DROP TABLE t1;