bk commit into 5.0 tree (evgen:1.2003) BUG#13293

[eugene]

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5.0 repository of evgen. When evgen does a push these changes will
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ChangeSet
  1.2003 05/11/24 19:54:02 evgen@stripped +3 -0
  Fix bug#13293 Wrongly used index results in endless loop.
  
  Loose index scan using only second part of multipart index was choosen, which
  results in creating wrong keys and endless loop.
  
  get_best_group_min_max() now allows loose index scan for distinct only if used
  keyparts forms a prefix of the index.

  sql/opt_range.cc
    1.199 05/11/24 19:50:01 evgen@stripped +13 -0
    Fix bug #13293 Wrongly used index results in endless loop.
    get_best_group_min_max() now allows loose index scan for distinct only if used keyparts forms a prefix of the index.

  mysql-test/r/group_min_max.result
    1.18 05/11/24 19:49:50 evgen@stripped +10 -0
    Test case for bug #13293 Wrongly used index results in endless loop.

  mysql-test/t/group_min_max.test
    1.16 05/11/24 19:49:25 evgen@stripped +10 -0
    Test case for bug #13293 Wrongly used index results in endless loop.

# 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:	evgen
# Host:	moonbone.local
# Root:	/work/13293-bug-5.0-mysql

--- 1.198/sql/opt_range.cc	2005-11-20 21:47:00 +03:00
+++ 1.199/sql/opt_range.cc	2005-11-24 19:50:01 +03:00
@@ -7197,6 +7197,7 @@
     {
       select_items_it.rewind();
       cur_used_key_parts.clear_all();
+      uint max_key_part= 0;
       while ((item= select_items_it++))
       {
         item_field= (Item_field*) item; /* (SA5) already checked above. */
@@ -7214,7 +7215,19 @@
         cur_group_prefix_len+= cur_part->store_length;
         cur_used_key_parts.set_bit(key_part_nr);
         ++cur_group_key_parts;
+        max_key_part= max(max_key_part,key_part_nr);
       }
+      /*
+        Check that used key parts forms a prefix of the index.
+        To check this we compare bits in all_parts and cur_parts.
+        all_parts have all bits set from 0 to (max_key_part-1).
+        cur_parts have bits set for only used keyparts.
+      */
+      ulonglong all_parts, cur_parts;
+      all_parts= (1<<max_key_part) - 1;
+      cur_parts= cur_used_key_parts.to_ulonglong() >> 1;
+      if (all_parts != cur_parts)
+        goto next_index;
     }
     else
       DBUG_ASSERT(FALSE);

--- 1.17/mysql-test/r/group_min_max.result	2005-09-25 17:43:52 +04:00
+++ 1.18/mysql-test/r/group_min_max.result	2005-11-24 19:49:50 +03:00
@@ -2002,3 +2002,13 @@
 1	1
 NULL	1
 drop table t1;
+create table t1 (f1 int, f2 char(1), primary key(f1,f2)) engine=innodb;
+insert into t1 values ( 1,"e"),(2,"a"),( 3,"c"),(4,"d");
+alter table t1 drop primary key, add primary key (f2, f1);
+explain select distinct f1 a, f1 b from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	5	NULL	4	Using index; Using temporary
+explain select distinct f1, f2 from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	NULL	PRIMARY	5	NULL	3	Using index for group-by; Using temporary
+drop table t1;

--- 1.15/mysql-test/t/group_min_max.test	2005-09-25 17:43:53 +04:00
+++ 1.16/mysql-test/t/group_min_max.test	2005-11-24 19:49:25 +03:00
@@ -693,3 +693,13 @@
 insert into t1 values(1);
 select a, count(a) from t1 group by a with rollup;
 drop table t1;
+
+#
+# Bug #13293 Wrongly used index results in endless loop.
+#
+create table t1 (f1 int, f2 char(1), primary key(f1,f2)) engine=innodb;
+insert into t1 values ( 1,"e"),(2,"a"),( 3,"c"),(4,"d");
+alter table t1 drop primary key, add primary key (f2, f1);
+explain select distinct f1 a, f1 b from t1;
+explain select distinct f1, f2 from t1;
+drop table t1;