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Allow keys with 0 segements in MyISAM

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This fixed a bug in SELECT DISTINCT when all selected parts where constants. (Bug #3203)


myisam/mi_create.c:
  Allow keys with 0 segements.
mysql-test/r/myisam.result:
  Test for problem with SELECT DISTINCT
mysql-test/t/myisam.test:
  Test for problem with SELECT DISTINCT
This commit is contained in:
unknown
2004-03-26 14:44:52 +02:00
parent 922818a798
commit cc11f6f351
3 changed files with 43 additions and 1 deletions
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8
myisam/mi_create.c
View File

@@ -366,7 +366,13 @@ int mi_create(const char *name,uint keys,MI_KEYDEF *keydefs,
my_errno=HA_WRONG_CREATE_OPTION;
goto err;
}
if ((keydef->flag & (HA_NOSAME | HA_NULL_PART_KEY)) == HA_NOSAME)
/*
key_segs may be 0 in the case when we only want to be able to
add on row into the table. This can happen with some DISTINCT queries
in MySQL
*/
if ((keydef->flag & (HA_NOSAME | HA_NULL_PART_KEY)) == HA_NOSAME &&
key_segs)
share.state.rec_per_key_part[key_segs-1]=1L;
length+=key_length;
keydef->block_length= MI_BLOCK_SIZE(length,pointer,MI_MAX_KEYPTR_SIZE);

22
mysql-test/r/myisam.result
View File

@@ -431,3 +431,25 @@ a concat(b,'.')
1 a.
3 a .
drop table t1;
create table t1 (a int not null);
create table t2 (a int not null, primary key (a));
insert into t1 values (1);
insert into t2 values (1),(2);
select sql_big_result distinct t1.a from t1,t2 order by t2.a;
a
1
select distinct t1.a from t1,t2 order by t2.a;
a
1
select sql_big_result distinct t1.a from t1,t2;
a
1
explain select sql_big_result distinct t1.a from t1,t2 order by t2.a;
table type possible_keys key key_len ref rows Extra
t1 system NULL NULL NULL NULL 1 Using temporary
t2 index NULL PRIMARY 4 NULL 2 Using index; Distinct
explain select distinct t1.a from t1,t2 order by t2.a;
table type possible_keys key key_len ref rows Extra
t1 system NULL NULL NULL NULL 1 Using temporary
t2 index NULL PRIMARY 4 NULL 2 Using index; Distinct
drop table t1,t2;

14
mysql-test/t/myisam.test
View File

@@ -422,3 +422,17 @@ update t1 set b='b ' where a > 1;
delete from t1 where b='b';
select a,concat(b,'.') from t1;
drop table t1;
#
# Test keys with 0 segments. (Bug #3203)
#
create table t1 (a int not null);
create table t2 (a int not null, primary key (a));
insert into t1 values (1);
insert into t2 values (1),(2);
select sql_big_result distinct t1.a from t1,t2 order by t2.a;
select distinct t1.a from t1,t2 order by t2.a;
select sql_big_result distinct t1.a from t1,t2;
explain select sql_big_result distinct t1.a from t1,t2 order by t2.a;
explain select distinct t1.a from t1,t2 order by t2.a;
drop table t1,t2;