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From:mhansson Date:January 25 2007 3:58pm
Subject:bk commit into 5.1 tree (mhansson:1.2409) BUG#20604
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Below is the list of changes that have just been committed into a local
5.1 repository of martin. When martin does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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ChangeSet@stripped, 2007-01-25 16:58:30+01:00, mhansson@stripped +5 -0
  BUG#20604: FORCE INDEX uses keys disabled by ALTER TABLE
   
  The function that checks whether we can use keys for aggregates,
  find_key_for_maxmin(), assumes that keys disabled by ALTER TABLE
  ... DISABLE KEYS are not in the set table->keys_in_use_for_query.
  I.E., if a key is in this set, the optimizer assumes it is free to 
  use it.
    
  The bug is that keys disabled with ALTER TABLE ... DISABLE KEYS still
  appear in table->keys_in_use_for_query When the TABLE object has been 
  initialized with setup_tables(). Before setup_tables is called, however, 
  keys that are disabled in the aforementioned way are not included in
  TABLE::keys_in_use_for_query. 
    
  The provided patch does the following:
   
  - changes the code that uses keys_is_use_for_query so that it assumes that
    keys_is_use_for_query already takes into account all disabled keys, and
    generally all keys that should be used by the query.
    
  - subtracts all disabled keys from keys_is_use_for_query early, during
    setup_tables, so that later phases can rely on consistent contents of
    keys_is_use_for_query.

  mysql-test/r/key.result@stripped, 2007-01-25 16:58:25+01:00, mhansson@stripped +7 -0
    Test for BUG#20604.
    The important part of the test is the explain output that 
    tests what indexes are used.

  mysql-test/t/key.test@stripped, 2007-01-25 16:58:25+01:00, mhansson@stripped +11 -0
    The minimal test case that reveals the bug. The optimizer for 
    aggregates did not take into account that keys might be the
    disabled on a table. The execution engine then tries to proceed
    and use the index, causing MyISAM to produce an error.

  sql/sql_base.cc@stripped, 2007-01-25 16:58:25+01:00, mhansson@stripped +1 -0
    Exclude the keys disabled by ALTER TABLE ... DISABLE_KEYS 
    from TABLE::keys_in_use_for_query

  sql/sql_select.cc@stripped, 2007-01-25 16:58:25+01:00, mhansson@stripped +6 -5
    The intersection operation between table->s->keys_in_use and 
    table->keys_in_use_for_query is no longer necessary. 
    We can trust that the latter is a subset of the former.

  sql/table.h@stripped, 2007-01-25 16:58:25+01:00, mhansson@stripped +22 -2
    Added comments to TABLE_SHARE::keys_in_use and 
    TABLE::keys_in_use_for_query.

# 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:	mhansson
# Host:	linux-st28.site
# Root:	/home/martin/mysql/src/5.1o-bug20604-tp

--- 1.372/sql/sql_base.cc	2007-01-24 16:51:05 +01:00
+++ 1.373/sql/sql_base.cc	2007-01-25 16:58:25 +01:00
@@ -5472,6 +5472,7 @@ bool setup_tables(THD *thd, Name_resolut
 	DBUG_RETURN(1);
       table->keys_in_use_for_query.subtract(map);
     }
+    table->keys_in_use_for_query.intersect(table->s->keys_in_use);
     table->used_keys.intersect(table->keys_in_use_for_query);
   }
   if (tablenr > MAX_TABLES)

--- 1.485/sql/sql_select.cc	2007-01-25 00:30:31 +01:00
+++ 1.486/sql/sql_select.cc	2007-01-25 16:58:25 +01:00
@@ -12262,13 +12262,14 @@ test_if_skip_sort_order(JOIN_TAB *tab,OR
   DBUG_ENTER("test_if_skip_sort_order");
   LINT_INIT(ref_key_parts);
 
+  /* Check which keys can be used to resolve ORDER BY. */
+  usable_keys= table->keys_in_use_for_query;
+
   /*
-    Check which keys can be used to resolve ORDER BY.
-    We must not try to use disabled keys.
+    Keys disabled by ALTER TABLE ... DISABLE KEYS should have already
+    been taken into account.
   */
-  usable_keys= table->s->keys_in_use;
-  /* we must not consider keys that are disabled by IGNORE INDEX */
-  usable_keys.intersect(table->keys_in_use_for_query);
+  DBUG_ASSERT(usable_keys.is_subset(table->s->keys_in_use));
 
   for (ORDER *tmp_order=order; tmp_order ; tmp_order=tmp_order->next)
   {

--- 1.158/sql/table.h	2007-01-15 10:39:27 +01:00
+++ 1.159/sql/table.h	2007-01-25 16:58:25 +01:00
@@ -158,7 +158,12 @@ typedef struct st_table_share
   LEX_STRING path;                	/* Path to .frm file (from datadir) */
   LEX_STRING normalized_path;		/* unpack_filename(path) */
   LEX_STRING connect_string;
-  key_map keys_in_use;                  /* Keys in use for table */
+
+  /* 
+     Set of keys in use, implemented as a Bitmap.
+     Excludes keys disabled by ALTER TABLE ... DISABLE KEYS.
+  */
+  key_map keys_in_use;
   key_map keys_for_keyread;
   ha_rows min_rows, max_rows;		/* create information */
   ulong   avg_row_length;		/* create information */
@@ -313,7 +318,22 @@ struct st_table {
   byte *write_row_record;		/* Used as optimisation in
 					   THD::write_row */
   byte *insert_values;                  /* used by INSERT ... UPDATE */
-  key_map quick_keys, used_keys, keys_in_use_for_query, merge_keys;
+
+  key_map quick_keys, used_keys;
+
+  /*
+    A set of keys that can be used in the query that references this
+    table 
+
+    All indexes disabled on the table's TABLE_SHARE (see TABLE::s)
+    will be subtracted from this set upon instantiation and during 
+    setup_tables, i.e. for any st_table t it holds that 
+    t.keys_in_use_for_query is a subset of t.s.keys_in_use.
+
+    The set is implemented as a bitmap.
+  */
+  key_map keys_in_use_for_query;
+  key_map merge_keys;
   KEY  *key_info;			/* data of keys in database */
 
   Field *next_number_field;		/* Set if next_number is activated */

--- 1.40/mysql-test/r/key.result	2006-08-11 23:06:20 +02:00
+++ 1.41/mysql-test/r/key.result	2007-01-25 16:58:25 +01:00
@@ -482,3 +482,10 @@ alter table t1 drop index i3, drop index
 alter table t1 add index i3 (c3), add index i2 (c2), add unique index i1 (c1);
 ERROR 23000: Duplicate entry '1' for key 'i1'
 drop table t1;
+CREATE TABLE t1( a TINYINT, KEY(a) ) ENGINE=MyISAM;
+INSERT INTO t1 VALUES( 1 );
+ALTER TABLE t1 DISABLE KEYS;
+EXPLAIN SELECT MAX(a) FROM t1 FORCE INDEX(a);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	
+drop table t1;

--- 1.31/mysql-test/t/key.test	2006-07-20 20:41:52 +02:00
+++ 1.32/mysql-test/t/key.test	2007-01-25 16:58:25 +01:00
@@ -442,3 +442,14 @@ alter table t1 drop index i3, drop index
 alter table t1 add index i3 (c3), add index i2 (c2), add unique index i1 (c1);
 drop table t1;
 
+
+#
+# Bug #20604: Test for disabled keys with aggregate functions and FORCE INDEX.
+#
+
+CREATE TABLE t1( a TINYINT, KEY(a) ) ENGINE=MyISAM;
+INSERT INTO t1 VALUES( 1 );
+ALTER TABLE t1 DISABLE KEYS;
+EXPLAIN SELECT MAX(a) FROM t1 FORCE INDEX(a);
+
+drop table t1;
Thread
bk commit into 5.1 tree (mhansson:1.2409) BUG#20604mhansson25 Jan