bk commit into 4.1 tree (sergefp:1.2455) BUG#15935

[Sergey Petrunia]

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4.1 repository of psergey. When psergey does a push these changes will
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ChangeSet
  1.2455 06/01/25 23:25:23 sergefp@stripped +3 -0
  BUG#15935: In mysql_update, don't use full index scan when we could have used quick
select scan.

  sql/sql_update.cc
    1.152 06/01/25 23:25:19 sergefp@stripped +1 -2
    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

  mysql-test/t/update.test
    1.27 06/01/25 23:25:19 sergefp@stripped +12 -0
    Testcase for BUG#15935

  mysql-test/r/update.result
    1.29 06/01/25 23:25:19 sergefp@stripped +15 -0
    Testcase for BUG#15935

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	sergefp
# Host:	newbox.mylan
# Root:	/home/psergey/mysql-4.1-bug15935

--- 1.151/sql/sql_update.cc	2005-12-27 12:36:11 +03:00
+++ 1.152/sql/sql_update.cc	2006-01-25 23:25:19 +03:00
@@ -212,7 +212,6 @@
       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 @@
 			   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);

--- 1.28/mysql-test/r/update.result	2005-12-01 23:20:44 +03:00
+++ 1.29/mysql-test/r/update.result	2006-01-25 23:25:19 +03:00
@@ -358,3 +358,18 @@
 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;

--- 1.26/mysql-test/t/update.test	2005-12-01 23:20:10 +03:00
+++ 1.27/mysql-test/t/update.test	2006-01-25 23:25:19 +03:00
@@ -287,4 +287,16 @@
 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