1set default_storage_engine='tokudb'; 2drop table if exists tt; 3create table tt (a int, b int, c int, d int, key(a), key(b), key(c)); 4insert into tt values (0,0,0,0),(1,0,0,0),(2,0,1,0),(3,0,1,0); 5show indexes from tt; 6Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment 7tt 1 a 1 a A 4 NULL NULL YES BTREE 8tt 1 b 1 b A 4 NULL NULL YES BTREE 9tt 1 c 1 c A 4 NULL NULL YES BTREE 10analyze table tt; 11Table Op Msg_type Msg_text 12test.tt analyze status OK 13show indexes from tt; 14Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment 15tt 1 a 1 a A 4 NULL NULL YES BTREE 16tt 1 b 1 b A 2 NULL NULL YES BTREE 17tt 1 c 1 c A 4 NULL NULL YES BTREE 18alter table tt drop key b, add key (d); 19show indexes from tt; 20Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment 21tt 1 a 1 a A 4 NULL NULL YES BTREE 22tt 1 c 1 c A 4 NULL NULL YES BTREE 23tt 1 d 1 d A 4 NULL NULL YES BTREE 24analyze table tt; 25Table Op Msg_type Msg_text 26test.tt analyze status OK 27show indexes from tt; 28Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment 29tt 1 a 1 a A 4 NULL NULL YES BTREE 30tt 1 c 1 c A 4 NULL NULL YES BTREE 31tt 1 d 1 d A 2 NULL NULL YES BTREE 32flush tables; 33show indexes from tt; 34Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment 35tt 1 a 1 a A 4 NULL NULL YES BTREE 36tt 1 c 1 c A 4 NULL NULL YES BTREE 37tt 1 d 1 d A 2 NULL NULL YES BTREE 38drop table tt; 39