MySQL Lists are EOL. Please join:

List:Commits« Previous MessageNext Message »
From:kgeorge Date:May 17 2007 4:38pm
Subject:bk commit into 5.0 tree (gkodinov:1.2445) BUG#22855
View as plain text  
Below is the list of changes that have just been committed into a local
5.0 repository of kgeorge. When kgeorge does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
For information on how to access the public repository
see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html

ChangeSet@stripped, 2007-05-17 19:38:34+03:00, gkodinov@stripped +3 -0
  Bug#22855:
  Conversion errors when constructing the condition for an
  IN predicates were treated as if the affected column contains
  NULL. If such a IN predicate is inside NOT we get wrong 
  results.
  Corrected the handling of conversion errors in an IN predicate 
  that is resolved by unique_subquery (through 
  subselect_uniquesubquery_engine).

  mysql-test/r/subselect3.result@stripped, 2007-05-17 19:38:26+03:00, gkodinov@stripped +18 -0
    Bug#22855: test case

  mysql-test/t/subselect3.test@stripped, 2007-05-17 19:38:27+03:00, gkodinov@stripped +18 -0
    Bug#22855: test case

  sql/item_subselect.cc@stripped, 2007-05-17 19:38:27+03:00, gkodinov@stripped +74 -7
    Bug#22855: corrected the handling of conversion errors and
    NULL key values in IN predicate that is resolved by index
    lookup.

# 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:	gkodinov
# Host:	macbook.gmz
# Root:	/Users/kgeorge/mysql/work/B22855-5.0-opt

--- 1.154/sql/item_subselect.cc	2007-03-09 07:05:05 +02:00
+++ 1.155/sql/item_subselect.cc	2007-05-17 19:38:27 +03:00
@@ -775,6 +775,11 @@ bool Item_in_subselect::val_bool()
   if (exec())
   {
     reset();
+    /* 
+      Must mark the IN predicate as NULL so as to make sure an enclosing NOT
+      predicate will return FALSE. See the comments in 
+      subselect_uniquesubquery_engine::copy_ref_key for further details.
+    */
     null_value= 1;
     return 0;
   }
@@ -1919,10 +1924,38 @@ int subselect_uniquesubquery_engine::sca
 
   DESCRIPTION
     Copy ref key and check for null parts in it.
+    Depending on the nullability and conversion problems this function
+    recognizes and processes the following states :
+      1. Partial match on top level. This means IN has a value of FALSE
+         regardless of the data in the subquery table.
+         Detected by finding a NULL in the left IN operand of a top level
+         expression.
+         We may actually skip reading the subquery, so return TRUE to skip
+         the table scan in subselect_uniquesubquery_engine::exec and make
+         the value of the IN predicate a NULL (that is equal to FALSE on
+         top level).
+      2. No exact match when IN is nested inside another predicate.
+         Detected by finding a NULL in the left IN operand when IN is not
+         a top level predicate.
+         We cannot have an exact match. But we must proceed further with a
+         table scan to find out if it's a partial match (and IN has a value
+         of NULL) or no match (and IN has a value of FALSE).
+         So we return FALSE to continue with the scan and see if there are
+         any record that would constitute a partial match (as we cannot
+         determine that from the index).
+      3. Error converting the left IN operand to the column type of the
+         right IN operand. This counts as no match (and IN has the value of
+         FALSE). We mark the subquery table cursor as having no more rows
+         (to ensure that the processing that follows will not find a match)
+         and return FALSE, so IN is not treated as returning NULL.
+
 
   RETURN
-    FALSE - ok, index lookup key without keys copied.
-    TRUE  - an error occured while copying the key
+    FALSE - The value of the IN predicate is not known. Proceed to find the
+            value of the IN predicate using the determined values of
+            null_keypart and table->status.
+    TRUE  - IN predicate has a value of NULL. Stop the processing right there
+            and return NULL to the outer predicates.
 */
 
 bool subselect_uniquesubquery_engine::copy_ref_key()
@@ -1942,13 +1975,37 @@ bool subselect_uniquesubquery_engine::co
       function.
     */
     null_keypart= (*copy)->null_key;
-    bool top_level= ((Item_in_subselect *) item)->is_top_level_item();
-    if (null_keypart && !top_level)
-      break;
-    if ((tab->ref.key_err) & 1 || (null_keypart && top_level))
+    if (null_keypart)
+    {
+      bool top_level= ((Item_in_subselect *) item)->is_top_level_item();
+      if (top_level)
+      {
+        /* Partial match on top level */
+        DBUG_RETURN(1);
+      }
+      else
+      {
+        /* No exact match when IN is nested inside another predicate */
+        break;
+      }
+    }
+
+    /*
+      Check if the error is equal to STORE_KEY_FATAL. This is not expressed 
+      using the store_key::store_key_result enum because ref.key_err is a 
+      boolean and we want to detect both TRUE and STORE_KEY_FATAL from the 
+      space of the union of the values of [TRUE, FALSE] and 
+      store_key::store_key_result.  
+      TODO: fix the variable an return types.
+    */
+    if (tab->ref.key_err & 1)
     {
+      /*
+       Error converting the left IN operand to the column type of the right
+       IN operand. 
+      */
       tab->table->status= STATUS_NOT_FOUND;
-      DBUG_RETURN(1);
+      break;
     }
   }
   DBUG_RETURN(0);
@@ -1991,10 +2048,20 @@ int subselect_uniquesubquery_engine::exe
   int error;
   TABLE *table= tab->table;
   empty_result_set= TRUE;
+  table->status= 0;
  
   /* TODO: change to use of 'full_scan' here? */
   if (copy_ref_key())
     DBUG_RETURN(1);
+  if (table->status)
+  {
+    /* 
+      We know that there will be no rows even if we scan. 
+      Can be set in copy_ref_key.
+    */
+    ((Item_in_subselect *) item)->value= 0;
+    DBUG_RETURN(0);
+  }
 
   if (null_keypart)
     DBUG_RETURN(scan_table());

--- 1.7/mysql-test/r/subselect3.result	2007-03-28 12:09:29 +03:00
+++ 1.8/mysql-test/r/subselect3.result	2007-05-17 19:38:26 +03:00
@@ -692,3 +692,21 @@ a	MAX(b)	test
 2	3	h
 3	4	i
 DROP TABLE t1, t2;
+CREATE TABLE t1 (a INT NOT NULL);
+INSERT INTO t1 VALUES (1),(-1), (65),(66);
+CREATE TABLE t2 (a INT UNSIGNED NOT NULL PRIMARY KEY);
+INSERT INTO t2 VALUES (65),(66);
+SELECT a FROM t1 WHERE a NOT IN (65,66);
+a
+1
+-1
+SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2);
+a
+1
+-1
+EXPLAIN SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
+2	DEPENDENT SUBQUERY	t2	unique_subquery	PRIMARY	PRIMARY	4	func	1	Using index
+DROP TABLE t1;
+End of 5.0 tests

--- 1.7/mysql-test/t/subselect3.test	2007-03-28 12:09:29 +03:00
+++ 1.8/mysql-test/t/subselect3.test	2007-05-17 19:38:27 +03:00
@@ -531,3 +531,21 @@ SELECT a, MAX(b),
 
 
 DROP TABLE t1, t2;
+
+#
+# Bug #22855: Optimizer doesn't rewrite NOT IN subselects to a correlated 
+# subquery 
+#
+CREATE TABLE t1 (a INT NOT NULL);
+INSERT INTO t1 VALUES (1),(-1), (65),(66);
+
+CREATE TABLE t2 (a INT UNSIGNED NOT NULL PRIMARY KEY);
+INSERT INTO t2 VALUES (65),(66);
+
+SELECT a FROM t1 WHERE a NOT IN (65,66);
+SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2);
+EXPLAIN SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2);
+
+DROP TABLE t1;
+
+--echo End of 5.0 tests
Thread
bk commit into 5.0 tree (gkodinov:1.2445) BUG#22855kgeorge17 May