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From:Tor Didriksen Date:February 11 2011 3:46pm
Subject:Re: bzr commit into mysql-5.5 branch (tor.didriksen:3323) Bug#60085
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this patch looks a bit simpler:

=== modified file 'sql/item.cc'
--- sql/item.cc    2011-01-31 10:37:16 +0000
+++ sql/item.cc    2011-02-11 15:44:19 +0000
@@ -7594,7 +7594,7 @@

   value_cached= TRUE;
   // Mark cached string value obsolete
-  str_value_cached= FALSE;
+//  str_value_cached= FALSE;
   /* Assume here that the underlying item will do correct conversion.*/
   int_value= example->val_int_result();
   null_value= example->null_value;


On Fri, Feb 11, 2011 at 4:38 PM, Jorgen Loland <jorgen.loland@stripped>wrote:

> Hi Tor,
>
> I'm afraid you're fixing the symptom instead of the problem.
>
> Consider your test case:
>
>
> SELECT 1 FROM t1 WHERE b < (SELECT CAST(a as date) FROM t1 GROUP BY a);
>
> The problem seems to be this
>
> 1) Item_cache_datetime is created for item "cast (a as date)".
>   This is first evaluated by calling val_str() due to
>   Item_cache_datetime::result_type() == STRING_RESULT
>
>   #0  Item_cache_datetime::val_str (this=0x1ad3178, str=0x1af79f8)
>       at /mysql/mysql-5.5/sql/item.cc:7526
>   #1  0x00000000007f078f in Item_singlerow_subselect::val_str
> (this=0x1af79e8,
>       str=0x1af79f8)
>       at /mysql/mysql-5.5/sql/item_subselect.cc:605
>   #2  0x00000000007840d4 in Item::save_in_field (this=0x1af79e8,
>       field=0x1af8310, no_conversions=true)
>       at /mysql/mysql-5.5/sql/item.cc:5385
>   #3  0x000000000077796a in Item::save_in_field_no_warnings
> (this=0x1af79e8,
>       field=0x1af8310, no_conversions=true)
>       at /mysql/mysql-5.5/sql/item.cc:1062
>
> 2) The Item_cache_datetime above is compared to column b, which is of type
> INT.
>   stored_field_cmp_to_item() decides that STRING and INT comparisons should
> be
>   performed by using REAL. By calling Item_cache_datetime::val_real(),
>   Item_copy_string::val_int() is called:
>
>   #0  Item_copy_string::val_int (this=0x1ad5f08)
>       at /mysql/mysql-5.5/sql/item.cc:3596
>   #1  0x000000000056d611 in Item::val_int_result (this=0x1ad5f08)
>       at /mysql/mysql-5.5/sql/item.h:845
>   #2  0x000000000078ac98 in Item_cache_datetime::cache_value_int
> (this=0x1ad3178)
>       at /mysql/mysql-5.5/sql/item.cc:7477
>   #3  0x000000000078b3c7 in Item_cache_datetime::val_real (this=0x1ad3178)
>       at /mysql/mysql-5.5/sql/item.cc:7601
>   #4  0x00000000007f0605 in Item_singlerow_subselect::val_real
> (this=0x1af7a78)
>       at /mysql/mysql-5.5/sql/item_subselect.cc:576
>   #5  0x000000000078a586 in stored_field_cmp_to_item (thd=0x1a36dd0,
>
>   But Item_copy_string::val_int() uses my_strntoll() to convert the String
>   "2011-05-13" to an int. This does not work because my_strntoll() stops
>   processing when it encounters "-", so the resulting int is 2011 instead
>   of the expected 20110513. In addition, the call to cache_value_int() sets
>   str_value_cached=FALSE.
>
> 3) When Item_cache_datetime::val_str() is later called,
> str_value_cached=FALSE.
>   It tries to convert 2011 to a string using number_to_datetime(). This
> fails.
>
>
> --
> Jørgen Løland | Senior Software Engineer | +47 73842138
> Oracle MySQL
> Trondheim, Norway
>
> --
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Thread
bzr commit into mysql-5.5 branch (tor.didriksen:3323) Bug#60085Tor Didriksen11 Feb
  • Re: bzr commit into mysql-5.5 branch (tor.didriksen:3323) Bug#60085Jorgen Loland11 Feb
    • Re: bzr commit into mysql-5.5 branch (tor.didriksen:3323) Bug#60085Tor Didriksen11 Feb
      • Re: bzr commit into mysql-5.5 branch (tor.didriksen:3323) Bug#60085Jorgen Loland14 Feb