1drop table if exists t; 2create table t (a int not null, b int not null, c int not null, d int not null, primary key(a,b), key(c,a)) engine=tokudb; 3insert into t values (0,0,0,0),(0,1,0,1); 4explain select c,a,b from t where c=0 and a=0 and b=1; 5id select_type table type possible_keys key key_len ref rows Extra 61 SIMPLE t const PRIMARY,c PRIMARY 8 const,const 1 7flush status; 8select c,a,b from t where c=0 and a=0 and b=1; 9c a b 100 0 1 11show status like 'handler_read%'; 12Variable_name Value 13Handler_read_first 0 14Handler_read_key 1 15Handler_read_last 0 16Handler_read_next 0 17Handler_read_prev 0 18Handler_read_retry 0 19Handler_read_rnd 0 20Handler_read_rnd_deleted 0 21Handler_read_rnd_next 0 22explain select c,a,b from t force index (c) where c=0 and a=0 and b=1; 23id select_type table type possible_keys key key_len ref rows Extra 241 SIMPLE t const c c 12 const,const,const 1 Using index 25flush status; 26select c,a,b from t force index (c) where c=0 and a=0 and b=1; 27c a b 280 0 1 29show status like 'handler_read%'; 30Variable_name Value 31Handler_read_first 0 32Handler_read_key 1 33Handler_read_last 0 34Handler_read_next 0 35Handler_read_prev 0 36Handler_read_retry 0 37Handler_read_rnd 0 38Handler_read_rnd_deleted 0 39Handler_read_rnd_next 0 40drop table t; 41