SET @save_opt= @@GLOBAL.innodb_prefix_index_cluster_optimization; set global innodb_prefix_index_cluster_optimization = ON; show variables like 'innodb_prefix_index_cluster_optimization'; Variable_name Value innodb_prefix_index_cluster_optimization ON SET @save_innodb_stats_persistent=@@GLOBAL.innodb_stats_persistent; SET GLOBAL innodb_stats_persistent = OFF; # Create a table with a large varchar field that we index the prefix # of and ensure we only trigger cluster lookups when we expect it. create table prefixinno ( id int not null, fake_id int not null, bigfield varchar(4096), primary key(id), index bigfield_idx (bigfield(32)), index fake_id_bigfield_prefix (fake_id, bigfield(32)) ) engine=innodb; insert into prefixinno values (1, 1001, repeat('a', 1)), (8, 1008, repeat('b', 8)), (24, 1024, repeat('c', 24)), (31, 1031, repeat('d', 31)), (32, 1032, repeat('x', 32)), (33, 1033, repeat('y', 33)), (128, 1128, repeat('z', 128)); select * from prefixinno; id fake_id bigfield 1 1001 a 8 1008 bbbbbbbb 24 1024 cccccccccccccccccccccccc 31 1031 ddddddddddddddddddddddddddddddd 32 1032 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 33 1033 yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy 128 1128 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz # Baseline sanity check: 0, 0. select "no-op query"; no-op query no-op query select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Eligible for optimization. select id, bigfield from prefixinno where bigfield = repeat('d', 31); id bigfield 31 ddddddddddddddddddddddddddddddd select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Eligible for optimization, access via fake_id only. select id, bigfield from prefixinno where fake_id = 1031; id bigfield 31 ddddddddddddddddddddddddddddddd select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Not eligible for optimization, access via fake_id of big row. select id, bigfield from prefixinno where fake_id = 1033; id bigfield 33 yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible for optimization. select id, bigfield from prefixinno where bigfield = repeat('x', 32); id bigfield 32 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible for optimization. select id, bigfield from prefixinno where bigfield = repeat('y', 33); id bigfield 33 yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Eligible, should not increment lookup counter. select id, bigfield from prefixinno where bigfield = repeat('b', 8); id bigfield 8 bbbbbbbb select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Eligible, should not increment lookup counter. select id, bigfield from prefixinno where bigfield = repeat('c', 24); id bigfield 24 cccccccccccccccccccccccc select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Should increment lookup counter. select id, bigfield from prefixinno where bigfield = repeat('z', 128); id bigfield 128 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Disable optimization, confirm we still increment counter. set global innodb_prefix_index_cluster_optimization = OFF; select id, bigfield from prefixinno where fake_id = 1033; id bigfield 33 yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 drop table prefixinno; # Multi-byte handling case set global innodb_prefix_index_cluster_optimization = ON; SET NAMES utf8mb4; CREATE TABLE t1( f1 varchar(10) CHARACTER SET UTF8MB4 COLLATE UTF8MB4_BIN, INDEX (f1(3)))ENGINE=INNODB; INSERT INTO t1 VALUES('a'), ('cccc'), ('až'), ('cčc'), ('ggᵷg'), ('¢¢'); INSERT INTO t1 VALUES('தமிழ்'), ('🐱🌑'), ('🌒'), ('🌑'); INSERT INTO t1 VALUES('😊me'), ('eu€'), ('ls¢'); # Eligible - record length is shorter than prefix SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'a'; f1 a select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like 'c%'; f1 cccc cčc select @cluster_lookups; @cluster_lookups 3 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Eligible - record length shorter than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'až'; f1 až select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'தமிழ்'; f1 தமிழ் select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like 'ggᵷ%'; f1 ggᵷg select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '😊%'; f1 😊me select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'ls¢'; f1 ls¢ select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Eligible - record length shorter than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '¢¢%'; f1 ¢¢ select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Eligible - record length shorter than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '🐱🌑%'; f1 🐱🌑 select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '🌑%'; f1 🌑 select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 2 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '🌒%'; f1 🌒 select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 2 DROP TABLE t1; # Multi-byte with minimum character length > 1 bytes CREATE TABLE t1( f1 varchar(10) CHARACTER SET UTF16 COLLATE UTF16_BIN, INDEX (f1(3)))ENGINE=INNODB; INSERT INTO t1 VALUES('a'), ('cccc'), ('až'), ('cčc'), ('ggᵷg'), ('¢¢'); INSERT INTO t1 VALUES('தமிழ்'), ('🐱🌑'), ('🌒'), ('🌑'); INSERT INTO t1 VALUES('😊me'), ('eu€'), ('ls¢'); # Eligible - record length is shorter than prefix SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'a'; f1 a select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like 'c%'; f1 cccc cčc select @cluster_lookups; @cluster_lookups 3 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Eligible - record length shorter than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'až'; f1 až select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'தமிழ்'; f1 தமிழ் select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like 'ggᵷ%'; f1 ggᵷg select @cluster_lookups; @cluster_lookups 2 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '😊%'; f1 😊me select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Not eligible - record length longer than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 = 'ls¢'; f1 ls¢ select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 # Eligible - record length shorter than prefix length SELECT f1 FROM t1 FORCE INDEX(`f1`) WHERE f1 like '¢¢%'; f1 ¢¢ select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Eligible - record length shorter than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '🐱🌑%'; f1 🐱🌑 select @cluster_lookups; @cluster_lookups 1 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Eligible - record length is shorter than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '🌑%'; f1 🌑 select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 2 # Eligible - record length is shorter than prefix length SELECT f1 FROM t1 FORCE INDEX (`f1`) WHERE f1 like '🌒%'; f1 🌒 select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 2 DROP TABLE t1; CREATE TABLE t1( col1 INT, col2 BLOB DEFAULT NULL, INDEX `idx1`(col2(4), col1))ENGINE=INNODB; INSERT INTO t1 VALUES (2, 'test'), (3, repeat('test1', 2000)); INSERT INTO t1(col1) VALUES(1); # Eligible - record length is shorter than prefix length SELECT col1 FROM t1 FORCE INDEX (`idx1`) WHERE col2 is NULL; col1 1 select @cluster_lookups; @cluster_lookups 0 select @cluster_lookups_avoided; @cluster_lookups_avoided 1 # Not eligible - record length longer than prefix index SELECT col1 FROM t1 FORCE INDEX (`idx1`) WHERE col2 like 'test1%'; col1 3 select @cluster_lookups; @cluster_lookups 2 select @cluster_lookups_avoided; @cluster_lookups_avoided 0 DROP TABLE t1; # # MDEV-20464 Division by 0 in row_search_with_covering_prefix() # CREATE TABLE t1 (f1 INT, f2 INT AS (f1), f3 INT AS (f1), f4 INT AS (f1), KEY (f1,f2,f3)) ENGINE=InnoDB; INSERT INTO t1 (f1) VALUES (NULL),(0); SELECT f1, MAX(f3), COUNT(f4) FROM t1 GROUP BY f1; f1 MAX(f3) COUNT(f4) NULL NULL 0 0 0 1 DROP TABLE t1; # # MDEV-23600 Division by 0 in row_search_with_covering_prefix() # CREATE TABLE t(c POINT UNIQUE) ENGINE=InnoDB; INSERT t SET c=POINT(1,1); SELECT * FROM t WHERE c > (SELECT MAX(c) FROM t); c DROP TABLE t; # # MDEV-12486 Wrong results with innodb_prefix_index_cluster_optimization # CREATE TABLE wp_blogs ( blog_id bigint(20) NOT NULL auto_increment, site_id bigint(20) NOT NULL default '0', domain varchar(200) NOT NULL default '', path varchar(100) NOT NULL default '', registered datetime NOT NULL default '0000-00-00 00:00:00', last_updated datetime NOT NULL default '0000-00-00 00:00:00', public tinyint(2) NOT NULL default '1', archived tinyint(2) NOT NULL default '0', mature tinyint(2) NOT NULL default '0', spam tinyint(2) NOT NULL default '0', deleted tinyint(2) NOT NULL default '0', lang_id int(11) NOT NULL default '0', PRIMARY KEY (blog_id), KEY domain (domain(50),path(5)), KEY lang_id (lang_id) ) ENGINE=InnoDB DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci; INSERT INTO wp_blogs (domain, path) VALUES ('domain.no', '/fondsinvesteringer/'), ('domain.no', '/'), ('foo', 'bar'), ('bar', 'foo'), ('foo', 'foo'), ('bar', 'bar'), ('foo', 'foobar'), ('bar', 'foobar'), ('foobar', 'foobar'); SET GLOBAL innodb_prefix_index_cluster_optimization=off; SELECT blog_id FROM wp_blogs WHERE domain IN ('domain.no') AND path IN ( '/fondsinvesteringer/', '/' ); blog_id 2 1 SET GLOBAL innodb_prefix_index_cluster_optimization=on; SELECT blog_id FROM wp_blogs WHERE domain IN ('domain.no') AND path IN ( '/fondsinvesteringer/', '/' ); blog_id 2 1 DROP TABLE wp_blogs; SET GLOBAL innodb_prefix_index_cluster_optimization = @save_opt; SET GLOBAL innodb_stats_persistent = @save_innodb_stats_persistent;