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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