bk commit into 4.1 tree (holyfoot:1.2677) BUG#29717

From: <holyfoot(at)mysql.com>
Date: Fri Jul 27 2007 - 07:46:48 EDT

Below is the list of changes that have just been committed into a local 4.1 repository of hf. When hf 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@1.2677, 2007-07-27 16:46:47+05:00, holyfoot@mysql.com +4 -0   Bug #29717 INSERT INTO SELECT inserts values even if    SELECT statement itself returns empty.   

  As a result of this bug some SELECT ... GROUP BY queries   return (NULL) row instead of empty recordset.   

  Ultimately failure happens in end_send_group() where we decide to   return the (NULL) row as JOIN::group is FALSE   

  We use different way to handle this SELECT in the INSERT INTO as we insert   in the same table what we use in the select. So we use temporary table,   and as we have suitable index, we can calculate group values at once   and store them in the temporary table. At the same time the table   whose field is in the GROUP BY contains just a single row, so optimizer   decides to remove the group list at all.   Still SELECT min(x) from empty_table; and

        SELECT min(x) from empty_table GROUP BY y; have to return different   results - first query should return the single (NULL) row, second -   an empty recordset.
  So this fix remembers the case when GROUP BY existed and was removed   by optimizer and suppress the (NULL) row if that was the case.

  mysql-test/r/insert_select.result@1.31, 2007-07-27 16:46:46+05:00, holyfoot@mysql.com +26 -0     Bug #29717 INSERT INTO SELECT inserts values even if      SELECT statement itself returns empty.     

    test result

  mysql-test/t/insert_select.test@1.25, 2007-07-27 16:46:46+05:00, holyfoot@mysql.com +28 -0     Bug #29717 INSERT INTO SELECT inserts values even if      SELECT statement itself returns empty.     

    test case

  sql/sql_select.cc@1.473, 2007-07-27 16:46:46+05:00, holyfoot@mysql.com +3 -1     Bug #29717 INSERT INTO SELECT inserts values even if      SELECT statement itself returns empty.     

    Remember the 'GROUP BY was optimized away' case in the JOIN::group_optimized     and check this in the end_send_group()

  sql/sql_select.h@1.82, 2007-07-27 16:46:46+05:00, holyfoot@mysql.com +2 -0     Bug #29717 INSERT INTO SELECT inserts values even if      SELECT statement itself returns empty.     

    JOIN::group_optimized member added to remember the 'GROUP BY optimied away'     case

diff -Nrup a/mysql-test/r/insert_select.result b/mysql-test/r/insert_select.result

--- a/mysql-test/r/insert_select.result	2006-06-19 15:22:38 +05:00

+++ b/mysql-test/r/insert_select.result	2007-07-27 16:46:46 +05:00

@@ -690,3 +690,29 @@ CREATE TABLE t1 (a int PRIMARY KEY);  INSERT INTO t1 values (1), (2);
 INSERT INTO t1 SELECT a + 2 FROM t1 LIMIT 1;  DROP TABLE t1;
+CREATE TABLE t1 (
+f1 int(10) unsigned NOT NULL auto_increment PRIMARY KEY,
+f2 varchar(100) NOT NULL default ''
+);
+CREATE TABLE t2 (
+f1 varchar(10) NOT NULL default '',
+f2 char(3) NOT NULL default '',
+PRIMARY KEY (`f1`),
+KEY `k1` (`f2`, `f1`)
+);
+INSERT INTO t1 values(NULL, '');
+INSERT INTO `t2` VALUES ('486878','WDT'),('486910','WDT');
+SELECT COUNT(*) FROM t1;
+COUNT(*)
+1
+SELECT min(t2.f1) FROM t1, t2 where t2.f2 = 'SIR' GROUP BY t1.f1;
+min(t2.f1)
+INSERT INTO t1 (f2)
+SELECT min(t2.f1) FROM t1, t2 where t2.f2 = 'SIR' GROUP BY t1.f1;
+SELECT COUNT(*) FROM t1;
+COUNT(*)
+1
+SELECT * FROM t1;
+f1 f2
+1
+DROP TABLE t1, t2;

diff -Nrup a/mysql-test/t/insert_select.test b/mysql-test/t/insert_select.test

--- a/mysql-test/t/insert_select.test	2006-06-19 15:22:38 +05:00

+++ b/mysql-test/t/insert_select.test	2007-07-27 16:46:46 +05:00

@@ -239,4 +239,32 @@ INSERT INTO t1 SELECT a + 2 FROM t1 LIMI  

 DROP TABLE t1;  

+#
+# Bug #29717 INSERT INTO SELECT inserts values even if SELECT statement itself returns empty
+#
+
+CREATE TABLE t1 (
+ f1 int(10) unsigned NOT NULL auto_increment PRIMARY KEY,
+ f2 varchar(100) NOT NULL default ''
+);
+CREATE TABLE t2 (
+ f1 varchar(10) NOT NULL default '',
+ f2 char(3) NOT NULL default '',
+ PRIMARY KEY (`f1`),
+ KEY `k1` (`f2`, `f1`)
+);
+
+INSERT INTO t1 values(NULL, '');
+INSERT INTO `t2` VALUES ('486878','WDT'),('486910','WDT');
+SELECT COUNT(*) FROM t1;
+
+SELECT min(t2.f1) FROM t1, t2 where t2.f2 = 'SIR' GROUP BY t1.f1;
+
+INSERT INTO t1 (f2)
+ SELECT min(t2.f1) FROM t1, t2 where t2.f2 = 'SIR' GROUP BY t1.f1;
+
+SELECT COUNT(*) FROM t1;
+SELECT * FROM t1;
+DROP TABLE t1, t2;
+

 # End of 4.1 tests
diff -Nrup a/sql/sql_select.cc b/sql/sql_select.cc

--- a/sql/sql_select.cc	2007-05-15 11:55:16 +05:00

+++ b/sql/sql_select.cc	2007-07-27 16:46:46 +05:00

@@ -777,6 +777,7 @@ JOIN::optimize()
     order=0;					// The output has only one row
     simple_order=1;
     select_distinct= 0;                       // No need in distinct for 1 row

+ group_optimized= 1;

   }  

   calc_group_buffer(this, group_list);
@@ -6896,7 +6897,8 @@ end_send_group(JOIN *join, JOIN_TAB *joi

   if (!join->first_record || end_of_records ||

       (idx=test_if_group_changed(join->group_fields)) >= 0)    {
- if (join->first_record || (end_of_records && !join->group))
+ if (join->first_record ||
+ (end_of_records && !join->group && !join->group_optimized))

     {
       if (join->procedure)
 	join->procedure->end_group();
diff -Nrup a/sql/sql_select.h b/sql/sql_select.h
--- a/sql/sql_select.h	2006-06-28 18:28:25 +05:00

+++ b/sql/sql_select.h	2007-07-27 16:46:46 +05:00

@@ -180,6 +180,7 @@ class JOIN :public Sql_alloc
   ROLLUP rollup;				// Used with rollup
 
   bool select_distinct;				// Set if SELECT DISTINCT

+ bool group_optimized; // Group list removed by optimizer
 

   /*
     simple_xxxxx is set if ORDER/GROUP BY doesn't include any references @@ -276,6 +277,7 @@ class JOIN :public Sql_alloc

     ref_pointer_array_size= 0;
     zero_result_cause= 0;
     optimized= 0;

+ group_optimized= 0;
 

     fields_list= fields_arg;
     bzero((char*) &keyuse,sizeof(keyuse));

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Received on Fri Jul 27 08:48:16 2007