Hi Ole John,
I've run into some problems with the patch:
First, compilation:
-------------------
cc1plus: warnings being treated as errors
sql_select.cc: In function ‘bool test_if_skip_sort_order(JOIN_TAB*, ORDER*,
ha_rows, bool, key_map*)’:
sql_select.cc:13674: error: value computed is not used
sql_select.cc:13703: error: unused variable ‘tmp’
sql_select.cc:13821: error: label ‘skiped_sort_order’ defined but not used
make[3]: *** [sql_select.o] Error 1
When I deal with these, I get a failed assertion from another test order_by:
--------------------
CURRENT_TEST: main.order_by
mysqltest: At line 239: query 'explain select * from t1 where a >= 1 and a < 3
order by a desc' failed: 2013: Lost connection to MySQL server during query
(...)
#6 0x00007ff305eaf941 in *__GI___assert_fail (
assertion=0xba6d4b "select->quick->sorted", file=<value optimized out>,
line=13795,
function=0xba7780 "bool test_if_skip_sort_order(JOIN_TAB*, ORDER*, ha_rows,
bool, key_map*)") at assert.c:81
#7 0x000000000071e6d4 in test_if_skip_sort_order (tab=0x1607520,
order=0x160a9b0, select_limit=18446744073709551615, no_changes=false,
map=0x162df98) at sql_select.cc:13795
#8 0x00000000006feea8 in JOIN::exec (this=0x1605c18) at sql_select.cc:1879
#9 0x00000000007013d1 in mysql_select (thd=0x15aaa88,
rref_pointer_array=0x15acb70, tables=0x1609e78, wild_num=1, fields=...,
conds=0x160a7a0, og_num=1, order=0x160a9b0, group=0x0, having=0x0,
proc_param=0x0, select_options=2147764740, result=0x160aa78,
unit=0x15ac578, select_lex=0x15ac9a0) at sql_select.cc:2545
#10 0x00000000007279b4 in mysql_explain_union (thd=0x15aaa88, unit=0x15ac578,
result=0x160aa78) at sql_select.cc:16971
#11 0x000000000069463d in execute_sqlcom_select (thd=0x15aaa88,
all_tables=0x1609e78) at sql_parse.cc:5136
#12 0x000000000068b62f in mysql_execute_command (thd=0x15aaa88)
at sql_parse.cc:2293
#13 0x0000000000696cec in mysql_parse (thd=0x15aaa88,
rawbuf=0x1609c58 "explain select * from t1 where a >= 1 and a < 3 order by
a desc", length=63, found_semicolon=0x7ff306db4960) at sql_parse.cc:6075
I can provide more details if you're unable to reproduce this assert.
$ bzr parent
bzr+ssh://bk-internal.mysql.com/bzrroot/server/mysql-5.1/
$ bzr revision-info
3534 georgi.kodinov@stripped
compiled with
BUILD/compile-amd64-debug-max-no-ndb
On 01/05/2011 02:48 PM, Ole John Aske wrote:
> #At file:///net/fimafeng09/export/home/tmp/oleja/mysql/mysql-5.1/ based on
> revid:nirbhay.choubey@stripped
>
> 3534 Ole John Aske 2011-01-05
> Fix for bug#59308: Incorrect result for SELECT DISTINCT<col>... ORDER
> BY<col> DESC.
>
> Also fix bug#59110: Memory leak of QUICK_SELECT_I allocated memory.
>
> Root cause of these bugs are that test_if_skip_sort_order() decided to
> revert the 'skip_sort_order' descision (and use filesort) after the
> query plan has been updated to reflect a 'skip' of the sort order.
>
> This might happen in 'check_reverse_order:' if we have a
> select->quick which could not be made descending by appending
> a QUICK_SELECT_DESC. ().
>
> The original 'save_quick' was then restored after the QEP has been modified,
> which caused:
>
> - An incorrect 'precomputed_group_by= TRUE' may have been set, and not
> reverted, as
> part of the already modifified QEP (Bug#59398)
> - A 'select->quick' might have been created which we fail to delete
> (bug#59110).
>
> This fix is a refactorication of test_if_skip_sort_order() where all logic
> related to modification of QEP (controlled by argument 'bool no_changes'), is
> moved to the end of test_if_skip_sort_order(), and done after *all*
> 'test_if_skip'
> checks has been performed - including the 'check_reverse_order:' checks.
>
> The refactorication above contains now intentional changes to the logic which
> has been
> moved to the end of the function.
>
> Furthermore, a smaller part of the fix address the handling of the
> select->quick objects
> which may already exists when we call 'test_if_skip_sort_order()' (save_quick)
> - and
> new select->quick's created during test_if_skip_sort_order():
>
> - Before new select->quick may be created by calling
> ::test_quick_select(), we
> set 'select->quick= 0' to avoid that ::test_quick_select() prematurely
> delete the save_quick's. (After this call we may have both a 'save_quick'
> and 'select->quick')
>
> - All returns from ::test_if_skip_sort_order() where we may have both a
> 'save_quick' and a 'select->quick' has been changed to goto's to the
> exit points 'skiped_sort_order:' or 'need_filesort:' where we
> decide which of the QUICK_SELECT's to keep, and delete the other.
>
> modified:
> mysql-test/r/order_by.result
> mysql-test/t/order_by.test
> sql/sql_select.cc
--
Jørgen Løland | Senior Software Engineer | +47 73842138
Oracle MySQL
Trondheim, Norway
