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BUG#15935: In mysql_update, don't use full index scan when we could have used quick select scan.

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mysql-test/r/update.result:
  Testcase for BUG#15935
mysql-test/t/update.test:
  Testcase for BUG#15935
sql/sql_update.cc:
  BUG#15935: 
  - Do account for the fact that used_index!=MAX_KEY is also true for cases
    when quick select is used, and use quick select then (and not full index scan).
  - Also removed the redundant "used_index= MAX_KEY" statement
This commit is contained in:
unknown 2006-01-25 23:25:23 +03:00
parent 52ff597a8a
commit d33ac37ba6
3 changed files with 28 additions and 2 deletions
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15
mysql-test/r/update.result
View File

@ -358,3 +358,18 @@ update t2,t1 set f1=3,f2=3 where f1=f2 and f1=1;
affected rows: 3
info: Rows matched: 3 Changed: 3 Warnings: 0
drop table t1,t2;
create table t1 (a int);
insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t2 (a int, filler1 char(200), filler2 char(200), key(a));
insert into t2 select A.a + 10*B.a, 'filler','filler' from t1 A, t1 B;
flush status;
update t2 set a=3 where a=2;
show status like 'handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 1
Handler_read_next 1
Handler_read_prev 0
Handler_read_rnd 1
Handler_read_rnd_next 0
drop table t1, t2;

12
mysql-test/t/update.test
View File

@ -287,4 +287,16 @@ update t1 set f1=1 where f1=3;
update t2,t1 set f1=3,f2=3 where f1=f2 and f1=1;
--disable_info
drop table t1,t2;
# BUG#15935
create table t1 (a int);
insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t2 (a int, filler1 char(200), filler2 char(200), key(a));
insert into t2 select A.a + 10*B.a, 'filler','filler' from t1 A, t1 B;
flush status;
update t2 set a=3 where a=2;
show status like 'handler_read%';
drop table t1, t2;
# End of 4.1 tests

3
sql/sql_update.cc
View File

@ -212,7 +212,6 @@ int mysql_update(THD *thd,
SORT_FIELD *sortorder;
ha_rows examined_rows;
used_index= MAX_KEY; // For call to init_read_record()
table->sort.io_cache = (IO_CACHE *) my_malloc(sizeof(IO_CACHE),
MYF(MY_FAE | MY_ZEROFILL));
if (!(sortorder=make_unireg_sortorder(order, &length)) ||
@ -244,7 +243,7 @@ int mysql_update(THD *thd,
DISK_BUFFER_SIZE, MYF(MY_WME)))
goto err;
if (used_index == MAX_KEY)
if (used_index == MAX_KEY || (select && select->quick))
init_read_record(&info,thd,table,select,0,1);
else
init_read_record_idx(&info, thd, table, 1, used_index);