drop table if exists t1; create table t1 ( pk1 int not null, pk2 int not null, key1 int not null, key2 int not null, pktail1ok int not null, pktail2ok int not null, pktail3bad int not null, pktail4bad int not null, pktail5bad int not null, pk2copy int not null, badkey int not null, filler1 char (200), filler2 char (200), key (key1), key (key2), /* keys with tails from CPK members */ key (pktail1ok, pk1), key (pktail2ok, pk1, pk2), key (pktail3bad, pk2, pk1), key (pktail4bad, pk1, pk2copy), key (pktail5bad, pk1, pk2, pk2copy), primary key (pk1, pk2) ) engine=innodb; explain select * from t1 where pk1 = 1 and pk2 < 80 and key1=0; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref PRIMARY,key1 PRIMARY 4 const 1 Using where select * from t1 where pk1 = 1 and pk2 < 80 and key1=0; pk1 pk2 key1 key2 pktail1ok pktail2ok pktail3bad pktail4bad pktail5bad pk2copy badkey filler1 filler2 1 10 0 0 0 0 0 0 0 10 0 filler-data-10 filler2 1 11 0 0 0 0 0 0 0 11 0 filler-data-11 filler2 1 12 0 0 0 0 0 0 0 12 0 filler-data-12 filler2 1 13 0 0 0 0 0 0 0 13 0 filler-data-13 filler2 1 14 0 0 0 0 0 0 0 14 0 filler-data-14 filler2 1 15 0 0 0 0 0 0 0 15 0 filler-data-15 filler2 1 16 0 0 0 0 0 0 0 16 0 filler-data-16 filler2 1 17 0 0 0 0 0 0 0 17 0 filler-data-17 filler2 1 18 0 0 0 0 0 0 0 18 0 filler-data-18 filler2 1 19 0 0 0 0 0 0 0 19 0 filler-data-19 filler2 explain select pk1,pk2 from t1 where key1 = 10 and key2=10 and 2*pk1+1 < 2*96+1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index_merge key1,key2 key1,key2 4,4 NULL 1 Using intersect(key1,key2); Using where; Using index select pk1,pk2 from t1 where key1 = 10 and key2=10 and 2*pk1+1 < 2*96+1; pk1 pk2 95 50 95 51 95 52 95 53 95 54 95 55 95 56 95 57 95 58 95 59 explain select * from t1 where badkey=1 and key1=10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref key1 key1 4 const 101 Using where explain select * from t1 where pk1 < 7500 and key1 = 10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index_merge PRIMARY,key1 key1,PRIMARY 4,4 NULL 38 Using intersect(key1,PRIMARY); Using where explain select * from t1 where pktail1ok=1 and key1=10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index_merge key1,pktail1ok key1,pktail1ok 4,4 NULL 1 Using intersect(key1,pktail1ok); Using where explain select * from t1 where pktail2ok=1 and key1=10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index_merge key1,pktail2ok key1,pktail2ok 4,4 NULL 1 Using intersect(key1,pktail2ok); Using where select ' The following is actually a deficiency, it uses sort_union currently:' as 'note:'; note: The following is actually a deficiency, it uses sort_union currently: explain select * from t1 where (pktail2ok=1 and pk1< 50000) or key1=10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index_merge PRIMARY,key1,pktail2ok pktail2ok,key1 8,4 NULL 199 Using sort_union(pktail2ok,key1); Using where explain select * from t1 where pktail3bad=1 and key1=10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref key1,pktail3bad pktail3bad 4 const ROWS Using where explain select * from t1 where pktail4bad=1 and key1=10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref key1,pktail4bad pktail4bad 4 const 99 Using where explain select * from t1 where pktail5bad=1 and key1=10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref key1,pktail5bad pktail5bad 4 const 99 Using where explain select pk1,pk2,key1,key2 from t1 where key1 = 10 and key2=10 limit 10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index_merge key1,key2 key1,key2 4,4 NULL 1 Using intersect(key1,key2); Using where; Using index select pk1,pk2,key1,key2 from t1 where key1 = 10 and key2=10 limit 10; pk1 pk2 key1 key2 95 50 10 10 95 51 10 10 95 52 10 10 95 53 10 10 95 54 10 10 95 55 10 10 95 56 10 10 95 57 10 10 95 58 10 10 95 59 10 10 drop table t1; create table t1 ( RUNID varchar(22), SUBMITNR varchar(5), ORDERNR char(1) , PROGRAMM varchar(8), TESTID varchar(4), UCCHECK char(1), ETEXT varchar(80), ETEXT_TYPE char(1), INFO char(1), SEVERITY tinyint(3), TADIRFLAG char(1), PRIMARY KEY (RUNID,SUBMITNR,ORDERNR,PROGRAMM,TESTID,UCCHECK), KEY `TVERM~KEY` (PROGRAMM,TESTID,UCCHECK) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; update t1 set `ETEXT` = '', `ETEXT_TYPE`='', `INFO`='', `SEVERITY`='', `TADIRFLAG`='' WHERE `RUNID`= '' AND `SUBMITNR`= '' AND `ORDERNR`='' AND `PROGRAMM`='' AND `TESTID`='' AND `UCCHECK`=''; drop table t1;