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order_by.result:

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result of the test case for FORCE INDEX on ORDER BY
order_by.test:
  test case for FORCE INDEX on ORDER BY
sql_select.cc:
  Changing behaviour that MySQL server takes FORCE INDEX clause into account when optimising ORDER BY clause
This commit is contained in:
Sinisa@sinisa.nasamreza.org
2004-03-26 17:01:13 +02:00
parent 2d970b2ea4
commit 09d26f0ff6
3 changed files with 32 additions and 3 deletions
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8
mysql-test/r/order_by.result
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@ -546,3 +546,11 @@ CREATE TABLE t1 (a INT, b INT);
SET @id=0;
UPDATE t1 SET a=0 ORDER BY (a=@id), b;
DROP TABLE t1;
create table t1(id int not null auto_increment primary key, t char(12));
explain select id,t from t1 order by id;
table type possible_keys key key_len ref rows Extra
t1 ALL NULL NULL NULL NULL 1000 Using filesort
explain select id,t from t1 force index (primary) order by id;
table type possible_keys key key_len ref rows Extra
t1 index NULL PRIMARY 4 NULL 1000
drop table t1;

13
mysql-test/t/order_by.test
View File

@ -352,4 +352,15 @@ CREATE TABLE t1 (a INT, b INT);
SET @id=0;
UPDATE t1 SET a=0 ORDER BY (a=@id), b;
DROP TABLE t1;
create table t1(id int not null auto_increment primary key, t char(12));
disable_query_log;
let $1 = 1000;
while ($1)
{
eval insert into t1(t) values ('$1');
dec $1;
}
enable_query_log;
explain select id,t from t1 order by id;
explain select id,t from t1 force index (primary) order by id;
drop table t1;

14
sql/sql_select.cc
View File

@ -6021,7 +6021,7 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
/* check if we can use a key to resolve the group */
/* Tables using JT_NEXT are handled here */
uint nr;
key_map keys=usable_keys;
key_map keys_to_use=~0,keys=usable_keys;
/*
If not used with LIMIT, only use keys if the whole query can be
@ -6029,7 +6029,17 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
retrieving all rows through an index.
*/
if (select_limit >= table->file->records)
keys&= (table->used_keys | table->file->keys_to_use_for_scanning());
keys_to_use= (table->used_keys |table->file->keys_to_use_for_scanning());
/*
We are adding here also the index speified in FORCE INDEX clause,
if any.
This is to allow users to use index in ORDER BY.
*/
if (table->force_index)
keys_to_use|= table->keys_in_use_for_query;
keys&= keys_to_use;
for (nr=0; keys ; keys>>=1, nr++)
{