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Fix bug#13293 Wrongly used index results in endless loop.

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Loose index scan using only second part of multipart index was choosen, which
results in creating wrong keys and endless loop.

get_best_group_min_max() now allows loose index scan for distinct only if used
keyparts forms a prefix of the index.


mysql-test/t/group_min_max.test:
  Test case for bug #13293 Wrongly used index results in endless loop.
mysql-test/r/group_min_max.result:
  Test case for bug #13293 Wrongly used index results in endless loop.
sql/opt_range.cc:
  Fix bug #13293 Wrongly used index results in endless loop.
  get_best_group_min_max() now allows loose index scan for distinct only if used keyparts forms a prefix of the index.
This commit is contained in:
unknown
2005-11-24 19:54:02 +03:00
parent b323bb273e
commit 591fabb390
3 changed files with 33 additions and 0 deletions
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10
mysql-test/r/group_min_max.result
View File

@ -2002,3 +2002,13 @@ a count(a)
1 1
NULL 1
drop table t1;
create table t1 (f1 int, f2 char(1), primary key(f1,f2)) engine=innodb;
insert into t1 values ( 1,"e"),(2,"a"),( 3,"c"),(4,"d");
alter table t1 drop primary key, add primary key (f2, f1);
explain select distinct f1 a, f1 b from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 5 NULL 4 Using index; Using temporary
explain select distinct f1, f2 from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL PRIMARY 5 NULL 3 Using index for group-by; Using temporary
drop table t1;

10
mysql-test/t/group_min_max.test
View File

@ -693,3 +693,13 @@ create table t1(a int, key(a)) engine=innodb;
insert into t1 values(1);
select a, count(a) from t1 group by a with rollup;
drop table t1;
#
# Bug #13293 Wrongly used index results in endless loop.
#
create table t1 (f1 int, f2 char(1), primary key(f1,f2)) engine=innodb;
insert into t1 values ( 1,"e"),(2,"a"),( 3,"c"),(4,"d");
alter table t1 drop primary key, add primary key (f2, f1);
explain select distinct f1 a, f1 b from t1;
explain select distinct f1, f2 from t1;
drop table t1;