From 426b551bf600e4c2d0a78227fe51dc009d0231c7 Mon Sep 17 00:00:00 2001
From: unknown <ramil/ram@mysql.com/ramil.myoffice.izhnet.ru>
Date: Fri, 19 Oct 2007 14:54:05 +0500
Subject: [PATCH] Fix for bug #31349: ERROR 1062 (23000): Duplicate entry ''
 for key 'group_key'

Problem: lying to the optimizer that a function (Item_func_inet_ntoa)
cannot return NULL values leads to unexpected results (in the case group
keys creation/comparison is broken).

Fix: Item_func_inet_ntoa::maybe_null should be set properly.


mysql-test/r/func_misc.result:
  Fix for bug #31349: ERROR 1062 (23000): Duplicate entry '' for key 'group_key'
    - test result.
mysql-test/t/func_misc.test:
  Fix for bug #31349: ERROR 1062 (23000): Duplicate entry '' for key 'group_key'
    - test case.
sql/item_strfunc.h:
  Fix for bug #31349: ERROR 1062 (23000): Duplicate entry '' for key 'group_key'
    - set Item_func_inet_ntoa::maybe_null flag.
---
 mysql-test/r/func_misc.result | 6 ++++++
 mysql-test/t/func_misc.test   | 8 ++++++++
 sql/item_strfunc.h            | 7 ++++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/func_misc.result b/mysql-test/r/func_misc.result
index 35101e26ff6..db2490bd261 100644
--- a/mysql-test/r/func_misc.result
+++ b/mysql-test/r/func_misc.result
@@ -185,4 +185,10 @@ ERROR 21000: Operand should contain 1 column(s)
 drop table table_26093;
 drop function func_26093_a;
 drop function func_26093_b;
+create table t1 (a int not null);
+insert into t1 values (-1), (-2);
+select min(a) from t1 group by inet_ntoa(a);
+min(a)
+-2
+drop table t1;
 End of 5.0 tests
diff --git a/mysql-test/t/func_misc.test b/mysql-test/t/func_misc.test
index 8ff62f68e45..5a70daa50e8 100644
--- a/mysql-test/t/func_misc.test
+++ b/mysql-test/t/func_misc.test
@@ -189,4 +189,12 @@ drop table table_26093;
 drop function func_26093_a;
 drop function func_26093_b;
 
+#
+# Bug #31349: ERROR 1062 (23000): Duplicate entry '' for key 'group_key'
+#
+create table t1 (a int not null);
+insert into t1 values (-1), (-2);
+select min(a) from t1 group by inet_ntoa(a);
+drop table t1;
+
 --echo End of 5.0 tests
diff --git a/sql/item_strfunc.h b/sql/item_strfunc.h
index 6ca0b89a22b..4ffd8125422 100644
--- a/sql/item_strfunc.h
+++ b/sql/item_strfunc.h
@@ -683,7 +683,12 @@ public:
     }
   String* val_str(String* str);
   const char *func_name() const { return "inet_ntoa"; }
-  void fix_length_and_dec() { decimals = 0; max_length=3*8+7; }
+  void fix_length_and_dec() 
+  { 
+    decimals= 0; 
+    max_length= 3 * 8 + 7; 
+    maybe_null= 1;
+  }
 };
 
 class Item_func_quote :public Item_str_func