verey Slow when use IN in table mysql 46.4878 sec - mysql

Question

Very very slow in the query when using IN
this query
SELECT *
FROM engine4_comment
WHERE sid IN (10,12,548,2110,5241,1255)
and this create table
CREATE TABLE `engine4_comment` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`sid` int(11) NOT NULL,
`rid` int(11) NOT NULL DEFAULT '0',
`uid` int(11) NOT NULL,
`text` longtext COLLATE utf8_unicode_ci NOT NULL,
`date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`active` int(11) NOT NULL DEFAULT '1',
`deleted` int(11) NOT NULL DEFAULT '0',
`deleted_reason` text CHARACTER SET latin1 NOT NULL,
`send_email` int(11) NOT NULL DEFAULT '1',
`user_active` tinyint(4) NOT NULL DEFAULT '1',
`dep_active` tinyint(4) NOT NULL DEFAULT '1',
PRIMARY KEY (`id`),
KEY `dat_idx` (`date`),
KEY `rid_idx` (`rid`),
KEY `rsid_idx` (`rid`,`sid`)
) ENGINE=InnoDB AUTO_INCREMENT=719329 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
and when use explaine explain SELECT * FROMengine4_commentWHERE sid IN (10,12,548,2110,5241,1255)
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE engine4_comment ALL NULL NULL NULL NULL 875583 Using where

Answer 1

This is your query:
SELECT *
FROM engine4_comment
WHERE sid IN (10,12,548,2110,5241,1255)
For performance, you want an index on sid. Either include a KEY statement in the create table. Or, explicitly create an index:
create index idx_engine4_comment_sid on engine4_comment(sid);
Note that the index rsid_idx doesn't help for this query, because sid is the second column. An index on (sid, rid) would benefit this query.