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MDEV-6105: Emoji unicode character string search query makes mariadb performance down

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- When range optimizer cannot the lookup value into [VAR]CHAR(n) column,
  it should produce:
  = "Impossible range" for equality
  = "no range" for non-equalities.
This commit is contained in:
Sergey Petrunya
2014-06-05 19:18:35 +04:00
parent 7d3a67a976
commit c7e5a1f70d
3 changed files with 103 additions and 0 deletions
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38
mysql-test/t/range.test
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@ -1638,3 +1638,41 @@ UPDATE v3 SET f3=0, f4=4 WHERE f2=68 ORDER BY f1;
SELECT * FROM v3;
DROP TABLE t1;
DROP VIEW v3;
--echo #
--echo # MDEV-6105: Emoji unicode character string search query makes mariadb performance down
--echo #
SET NAMES utf8;
DROP TABLE IF EXISTS t1;
CREATE TABLE t1(
id int AUTO_INCREMENT,
fd varchar(20),
primary key(id),
index ix_fd(fd)
)engine=innodb default charset=UTF8;
INSERT INTO t1(id, fd) VALUES (null, ''),(null, 'matt'),(null, 'pitt'),(null, 'lee'),(null, 'kim');
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
INSERT INTO t1 (fd) SELECT fd FROM t1;
--echo # The following should show "Impossible WHERE" :
explain
SELECT * FROM t1 WHERE fd='😁';
SELECT * FROM t1 WHERE fd='😁';
--echo # The following must not use range access:
explain select count(*) from t1 where fd <'😁';
select count(*) from t1 where fd <'😁';
select count(*) from t1 ignore index (ix_fd) where fd <'😁';
drop table t1;
set names default;