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

[holyfoot]

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ChangeSet@stripped, 2007-07-27 16:46:47+05:00, holyfoot@stripped +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@stripped, 2007-07-27 16:46:46+05:00, holyfoot@stripped
+26 -0
    Bug #29717 INSERT INTO SELECT inserts values even if
     SELECT statement itself returns empty.
    
    test result

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

  sql/sql_select.cc@stripped, 2007-07-27 16:46:46+05:00, holyfoot@stripped +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@stripped, 2007-07-27 16:46:46+05:00, holyfoot@stripped +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));