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BUG#17314: Can't use index_merge/intersection for MERGE tables

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1. Fix index access costs for MERGE tables, set block_size=myisam_block_size/#underlying_tables 
   instead of 0 which it was before.
2. Make index scans on MERGE table to return records in (key_tuple, merge_table_rowid) order, 
   instead of just (key_tuple) order. This makes an index scan on MERGE table to be truly a ROR-scan
   which is a requirement for index_merge union/intersection.


myisammrg/myrg_queue.c:
  BUG#17314: Make index scans on MERGE table return records ordered by (keytuple, merge_table_rowid).
mysql-test/r/index_merge.result:
  Testcase for BUG#17314
mysql-test/r/merge.result:
  BUG#17314: update testcase result
mysql-test/t/index_merge.test:
  Testcase for BUG#17314
sql/ha_myisammrg.cc:
  BUG#17314: For MERGE tables, set handler::block_size to myisam_block_size/#underlying_tables, and not to 0.
This commit is contained in:
unknown
2006-02-11 21:51:43 +03:00
parent 96268d4a9a
commit 4b0cce4873
5 changed files with 87 additions and 5 deletions
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22
mysql-test/r/index_merge.result
View File

@ -402,3 +402,25 @@ explain select * from t1 force index(cola,colb) WHERE cola = 'foo' AND colb = 'b
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index_merge cola,colb cola,colb 3,3 NULL 24 Using intersect(cola,colb); Using where
drop table t1;
create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (
a int, b int,
filler1 char(200), filler2 char(200),
key(a),key(b)
);
insert into t1 select @v:= A.a, @v, 't1', 'filler2' from t0 A, t0 B, t0 C;
create table t2 like t1;
create table t3 (
a int, b int,
filler1 char(200), filler2 char(200),
key(a),key(b)
) engine=merge union=(t1,t2);
explain select * from t1 where a=1 and b=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index_merge a,b a,b 5,5 NULL # Using intersect(a,b); Using where
explain select * from t3 where a=1 and b=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index_merge a,b a,b 5,5 NULL # Using intersect(a,b); Using where
drop table t3;
drop table t0, t1, t2;

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

@ -56,8 +56,8 @@ a b
4 Testing
5 table
5 table
6 t1
6 t2
6 t1
7 Testing
7 Testing
8 table

26
mysql-test/t/index_merge.test
View File

@ -357,3 +357,29 @@ explain select * from t1 WHERE cola = 'foo' AND colb = 'bar';
explain select * from t1 force index(cola,colb) WHERE cola = 'foo' AND colb = 'bar';
drop table t1;
#
# BUG#17314: Index_merge/intersection not choosen by the optimizer for MERGE tables
#
create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (
a int, b int,
filler1 char(200), filler2 char(200),
key(a),key(b)
);
insert into t1 select @v:= A.a, @v, 't1', 'filler2' from t0 A, t0 B, t0 C;
create table t2 like t1;
create table t3 (
a int, b int,
filler1 char(200), filler2 char(200),
key(a),key(b)
) engine=merge union=(t1,t2);
--replace_column 9 #
explain select * from t1 where a=1 and b=1;
--replace_column 9 #
explain select * from t3 where a=1 and b=1;
drop table t3;
drop table t0, t1, t2;