# Test for Bug #30423, InnoDBs treatment of NULL in index stats causes # bad "rows examined" estimates. # Implemented InnoDB system variable "innodb_stats_method" with # "nulls_equal" (default), "nulls_unequal", and "nulls_ignored" options. -- source include/have_innodb_plugin.inc let $innodb_stats_method_orig = `select @@innodb_stats_method`; # default setting for innodb_stats_method is "nulls_equal" set global innodb_stats_method = default; select @@innodb_stats_method; # create three tables, bug30243_1, bug30243_2 and bug30243_3. # The test scenario is adopted from original bug #30423 report. # table bug30243_1 and bug30243_3 have many NULL values -- disable_result_log -- disable_query_log DROP TABLE IF EXISTS bug30243_1; CREATE TABLE bug30243_1 ( org_id int(11) NOT NULL default '0', UNIQUE KEY (org_id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; LOCK TABLES bug30243_1 WRITE; INSERT INTO bug30243_1 VALUES (11),(15),(16),(17),(19),(20),(21),(23),(24), (25),(26),(27),(28),(29),(30),(31),(32),(33),(34),(35),(37),(38),(40),(41), (42),(43),(44),(45),(46),(47),(48),(49),(50),(51),(52),(53),(54),(55),(56), (57),(58),(59),(60),(61),(62),(63),(64),(65),(66),(67),(68),(69),(70),(71), (72),(73),(74),(75),(76),(77),(78),(79),(80),(81),(82),(83),(84),(85),(86), (87),(88),(89),(90),(91),(92),(93),(94),(95),(96),(97),(98),(99),(100),(101), (102),(103),(104),(105),(106),(107),(108),(109),(110),(111),(112),(113),(114), (115),(116),(117),(118),(119),(120),(121),(122),(123),(124),(125),(126),(127), (128),(129),(130),(131),(132),(133),(134),(135),(136),(137),(138),(139),(140), (141),(142),(143),(144),(145); UNLOCK TABLES; DROP TABLE IF EXISTS bug30243_3; CREATE TABLE bug30243_3 ( org_id int(11) default NULL, KEY (org_id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO bug30243_3 VALUES (NULL); begin; let $i=14; while ($i) { INSERT INTO bug30243_3 SELECT NULL FROM bug30243_3; dec $i; } INSERT INTO bug30243_3 VALUES (34),(34),(35),(56),(58),(62),(62),(64),(65),(66),(80),(135),(137),(138),(139),(140),(142),(143),(144),(145); commit; DROP TABLE IF EXISTS bug30243_2; CREATE TABLE bug30243_2 ( org_id int(11) default NULL, KEY `contacts$org_id` (org_id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO bug30243_2 VALUES (NULL); begin; let $i=16; while ($i) { INSERT INTO bug30243_2 SELECT NULL FROM bug30243_2; dec $i; } INSERT INTO bug30243_2 VALUES (11),(15),(16),(17),(20),(21),(23),(24),(25), (26),(27),(28),(29),(30),(31),(32),(33),(34),(37),(38),(40),(41),(42),(43), (44),(45),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46), (46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46), (46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46), (46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46), (46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46), (46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(46),(48), (48),(50),(51),(52),(52),(53),(54),(55),(57),(60),(61),(62),(62),(62),(62), (62),(63),(64),(64),(65),(66),(66),(67),(68),(69),(70),(71),(72),(73),(74), (75),(76),(77),(78),(79),(80),(80),(81),(82),(83),(84),(85),(86),(87),(88), (89),(90),(91),(92),(93),(94),(95),(96),(97),(98),(99),(100),(101),(102), (103),(104),(105),(106),(107),(108),(109),(110),(111),(112),(113),(114), (115),(116),(117),(118),(119),(120),(121),(122),(123),(124),(125),(126), (127),(128),(129),(130),(131),(132),(133),(133),(135),(135),(135),(135), (136),(136),(138),(138),(139),(139),(139),(140),(141),(141),(142),(143), (143),(145),(145); commit; -- enable_result_log -- enable_query_log # check tables's value select count(*) from bug30243_3 where org_id is not NULL; select count(*) from bug30243_3 where org_id is NULL; select count(*) from bug30243_2 where org_id is not NULL; select count(*) from bug30243_2 where org_id is NULL; select @@innodb_stats_method; analyze table bug30243_1; analyze table bug30243_2; analyze table bug30243_3; # Following query plan shows that we over estimate the rows per # unique value (since there are many NULLs). # Skip this query log since the stats estimate could vary from runs -- disable_query_log -- disable_result_log explain SELECT COUNT(*), 0 FROM bug30243_1 orgs LEFT JOIN bug30243_3 sa_opportunities ON orgs.org_id=sa_opportunities.org_id LEFT JOIN bug30243_2 contacts ON orgs.org_id=contacts.org_id ; -- enable_query_log -- enable_result_log # following set operation will fail #--error ER_WRONG_VALUE_FOR_VAR --error 1231 set global innodb_stats_method = "NULL"; set global innodb_stats_method = "nulls_ignored"; select @@innodb_stats_method; # Regenerate the stats with "nulls_ignored" option analyze table bug30243_1; analyze table bug30243_2; analyze table bug30243_3; # Following query plan shows that we get the correct rows per # unique value (should be approximately 1 row per value) explain SELECT COUNT(*), 0 FROM bug30243_1 orgs LEFT JOIN bug30243_3 sa_opportunities ON orgs.org_id=sa_opportunities.org_id LEFT JOIN bug30243_2 contacts ON orgs.org_id=contacts.org_id ; select @@innodb_stats_method; # Try the "nulls_unequal" option set global innodb_stats_method = "nulls_unequal"; select @@innodb_stats_method; analyze table bug30243_1; analyze table bug30243_2; analyze table bug30243_3; # Following query plan shows that we get the correct rows per # unique value (~1) explain SELECT COUNT(*), 0 FROM bug30243_1 orgs LEFT JOIN bug30243_3 sa_opportunities ON orgs.org_id=sa_opportunities.org_id LEFT JOIN bug30243_2 contacts ON orgs.org_id=contacts.org_id; # Create a table with all NULL values, make sure the stats calculation # does not crash with table of all NULL values -- disable_query_log CREATE TABLE table_bug30423 ( org_id int(11) default NULL, KEY(org_id) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `table_bug30423` VALUES (NULL); begin; let $i=10; while ($i) { INSERT INTO table_bug30423 SELECT NULL FROM table_bug30423; dec $i; } commit; -- enable_query_log SELECT COUNT(*) FROM table_bug30423 WHERE org_id IS NULL; # calculate the statistics for the table for "nulls_ignored" and # "nulls_unequal" option set global innodb_stats_method = "nulls_unequal"; analyze table table_bug30423; set global innodb_stats_method = "nulls_ignored"; analyze table table_bug30423; eval set global innodb_stats_method = $innodb_stats_method_orig; drop table bug30243_2; drop table bug30243_1; drop table bug30243_3; drop table table_bug30423;