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select.result, select.test:

Browse Source 
Added a test case for bug #5333.
null_key.result, key_primary.result:
  Made covering index usable for const tables.
sql_select.cc:
  Made covering index usable for const tables:
  downported the corresponding code from 4.1.
  Simultaneously fixed bug #5333 reported for 4.1.
  The bug was due to the fact that field index in join
  structures was always set to 0 for const tables.
This commit is contained in:
igor@rurik.mysql.com
2004-09-02 22:06:30 -07:00
parent 4b760fcb94
commit f888026fdc
5 changed files with 49 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
mysql-test/r/key_primary.result
View File

@ -13,7 +13,7 @@ t1
AB%
describe select * from t1 where t1="ABC";
table type possible_keys key key_len ref rows Extra
t1 const PRIMARY PRIMARY 3 const 1
t1 const PRIMARY PRIMARY 3 const 1 Using index
describe select * from t1 where t1="ABCD";
Comment
Impossible WHERE noticed after reading const tables

2
mysql-test/r/null_key.result
View File

@ -12,7 +12,7 @@ table type possible_keys key key_len ref rows Extra
t1 ref a,b a 9 const,const 1 Using where; Using index
explain select * from t1 where a=2 and b = 2;
table type possible_keys key key_len ref rows Extra
t1 const a,b a 9 const,const 1
t1 const a,b a 9 const,const 1 Using index
explain select * from t1 where a<=>b limit 2;
table type possible_keys key key_len ref rows Extra
t1 index NULL a 9 NULL 12 Using where; Using index

16
mysql-test/r/select.result
View File

@ -2327,3 +2327,19 @@ select * from t2,t3 where t2.s = t3.s;
s s
two two
drop table t1, t2, t3;
CREATE TABLE t1 (
i int(11) NOT NULL default '0',
c char(10) NOT NULL default '',
PRIMARY KEY (i),
UNIQUE KEY c (c)
) TYPE=MyISAM;
INSERT INTO t1 VALUES (1,'a');
INSERT INTO t1 VALUES (2,'b');
INSERT INTO t1 VALUES (3,'c');
EXPLAIN SELECT i FROM t1 WHERE i=1;
table type possible_keys key key_len ref rows Extra
t1 const PRIMARY PRIMARY 4 const 1 Using index
EXPLAIN SELECT i FROM t1 WHERE i=1;
table type possible_keys key key_len ref rows Extra
t1 const PRIMARY PRIMARY 4 const 1 Using index
DROP TABLE t1;

21
mysql-test/t/select.test
View File

@ -1874,3 +1874,24 @@ select * from t3 where s = 'one';
select * from t1,t2 where t1.s = t2.s;
select * from t2,t3 where t2.s = t3.s;
drop table t1, t2, t3;
#
# Covering index is mentioned in EXPLAIN output for const tables (bug #5333)
#
CREATE TABLE t1 (
i int(11) NOT NULL default '0',
c char(10) NOT NULL default '',
PRIMARY KEY (i),
UNIQUE KEY c (c)
) TYPE=MyISAM;
INSERT INTO t1 VALUES (1,'a');
INSERT INTO t1 VALUES (2,'b');
INSERT INTO t1 VALUES (3,'c');
EXPLAIN SELECT i FROM t1 WHERE i=1;
EXPLAIN SELECT i FROM t1 WHERE i=1;
DROP TABLE t1;

11
sql/sql_select.cc
View File

@ -4901,6 +4901,15 @@ join_read_const_table(JOIN_TAB *tab, POSITION *pos)
}
else
{
if (!table->key_read &&
(table->used_keys & ((key_map) 1 << tab->ref.key)) &&
!table->no_keyread &&
(int) table->reginfo.lock_type <= (int) TL_READ_HIGH_PRIORITY)
{
table->key_read=1;
table->file->extra(HA_EXTRA_KEYREAD);
tab->index= tab->ref.key;
}
if ((error=join_read_const(tab)))
{
tab->info="unique row not found";
@ -7617,7 +7626,7 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
sprintf(buff3,"%.0f",join->best_positions[i].records_read);
item_list.push_back(new Item_string(buff3,strlen(buff3)));
my_bool key_read=table->key_read;
if (tab->type == JT_NEXT &&
if ((tab->type == JT_NEXT || tab->type == JT_CONST) &&
((table->used_keys & ((key_map) 1 << tab->index))))
key_read=1;