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Re: [Postgres-xc-developers] Query Planning bug ?
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From: Tomonari K. <kat...@po...> - 2013-06-17 06:13:37
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Hi Ashtosh,
Sorry for slow response.
I've watched the each lists at list_concat function.
This function is called several times, but the lists before
last infinitely roop are like below.
[list1]
(gdb) p *list1->head
$18 = {data = {ptr_value = 0x17030e8, int_value = 24129768,
oid_value = 24129768}, next = 0x170d418}
(gdb) p *list1->head->next
$19 = {data = {ptr_value = 0x17033d0, int_value = 24130512,
oid_value = 24130512}, next = 0x170fd40}
(gdb) p *list1->head->next->next
$20 = {data = {ptr_value = 0x170ae58, int_value = 24161880,
oid_value = 24161880}, next = 0x171e6c8}
(gdb) p *list1->head->next->next->next
$21 = {data = {ptr_value = 0x1702ca8, int_value = 24128680,
oid_value = 24128680}, next = 0x171ed28}
(gdb) p *list1->head->next->next->next->next
$22 = {data = {ptr_value = 0x170af68, int_value = 24162152,
oid_value = 24162152}, next = 0x171f3a0}
(gdb) p *list1->head->next->next->next->next->next
$23 = {data = {ptr_value = 0x170b0a8, int_value = 24162472,
oid_value = 24162472}, next = 0x170b7c0}
(gdb) p *list1->head->next->next->next->next->next->next
$24 = {data = {ptr_value = 0x17035f0, int_value = 24131056,
oid_value = 24131056}, next = 0x1720998}
---- from ---
(gdb) p *list1->head->next->next->next->next->next->next->next
$25 = {data = {ptr_value = 0x17209b8, int_value = 24250808,
oid_value = 24250808}, next = 0x1721190}
(gdb) p *list1->head->next->next->next->next->next->next->next->next
$26 = {data = {ptr_value = 0x17211b0, int_value = 24252848,
oid_value = 24252848}, next = 0x1721988}
(gdb) p *list1->head->next->next->next->next->next->next->next->next->next
$27 = {data = {ptr_value = 0x17219a8, int_value = 24254888,
oid_value = 24254888}, next = 0x1722018}
(gdb) p
*list1->head->next->next->next->next->next->next->next->next->next->next
$28 = {data = {ptr_value = 0x1722038, int_value = 24256568,
oid_value = 24256568}, next = 0x1722820}
(gdb) p
*list1->head->next->next->next->next->next->next->next->next->next->next->next
$29 = {data = {ptr_value = 0x1722840, int_value = 24258624,
oid_value = 24258624}, next = 0x0}
---- to ----
[list2]
(gdb) p *list2->head
$31 = {data = {ptr_value = 0x17209b8, int_value = 24250808,
oid_value = 24250808}, next = 0x1721190}
(gdb) p *list2->head->next
$32 = {data = {ptr_value = 0x17211b0, int_value = 24252848,
oid_value = 24252848}, next = 0x1721988}
(gdb) p *list2->head->next->next
$33 = {data = {ptr_value = 0x17219a8, int_value = 24254888,
oid_value = 24254888}, next = 0x1722018}
(gdb) p *list2->head->next->next->next
$34 = {data = {ptr_value = 0x1722038, int_value = 24256568,
oid_value = 24256568}, next = 0x1722820}
(gdb) p *list2->head->next->next->next->next
$35 = {data = {ptr_value = 0x1722840, int_value = 24258624,
oid_value = 24258624}, next = 0x0}
----
list1's last five elements are same with list2's all elements.
(in above example, between "from" and "to" in list1 equal all of list2)
This is cause of infinitely roop, but I can not
watch deeper.
Because some values from gdb are optimized and un-displayed.
I tried compile with CFLAGS=O0, but I can't.
What can I do more ?
regards,
------------------
NTT Software Corporation
Tomonari Katsumata
(2013/06/12 21:04), Ashutosh Bapat wrote:
> Hi Tomonari,
> Can you please check the list's sanity before calling pgxc_collect_RTE()
> and at every point in the minions of this function. My primary suspect is
> the line pgxcplan.c:3094. We should copy the list before
concatenating it.
>
>
> On Wed, Jun 12, 2013 at 2:26 PM, Tomonari Katsumata <
> kat...@po...> wrote:
>
>> Hi Ashutosh,
>>
>> Thank you for the response.
>>
>> (2013/06/12 14:43), Ashutosh Bapat wrote:
>> >> Hi,
>> >> >
>> >> > I've investigated this problem(BUG:3614369).
>> >> >
>> >> > I caught the cause of it, but I can not
>> >> > find where to fix.
>> >> >
>> >> > The problem occurs when "pgxc_collect_RTE_walker" is called
>> infinitely.
>> >> > It seems that rtable(List of RangeTable) become cyclic List.
>> >> > I'm not sure where the List is made.
>> >> >
>> >> >
>> > I guess, we are talking about EXECUTE DIRECT statement that you have
>> > mentioned earlier.
>>
>> Yes, that's right.
>> I'm talking about EXECUTE DIRECT statement like below.
>> ---
>> EXECUTE DIRECT ON (data1) $$
>> SELECT
>> count(*)
>> FROM
>> (SELECT * FROM pg_locks l LEFT JOIN
>> (SELECT * FROM pg_stat_activity) s ON l.database = s.datid) a
>> $$
>> ---
>>
>> > The function pgxc_collect_RTE_walker() is a recursive
>> > function. The condition to end the recursion is if the given node is
>> NULL.
>> > We have to look at if that condition is met and if not why.
>> >
>> I investigated it deeper, and I noticed that
>> the infinitely loop happens at the function "range_table_walker()".
>>
>> Please see below trace.
>> ===========================
>> Breakpoint 1, range_table_walker (rtable=0x15e7968, walker=0x612c70
>> <pgxc_collect_RTE_walker>, context=0x7fffd2de31c0,
>> flags=0) at nodeFuncs.c:1908
>> 1908 in nodeFuncs.c
>>
>> (gdb) p *rtable
>> $10 = {type = T_List, length = 5, head = 0x15e7998, tail = 0x15e9820}
>> (gdb) p *rtable->head
>> $11 = {data = {ptr_value = 0x15e79b8, int_value = 22968760, oid_value =
>> 22968760}, next = 0x15e8190}
>> (gdb) p *rtable->head->next
>> $12 = {data = {ptr_value = 0x15e81b0, int_value = 22970800, oid_value =
>> 22970800}, next = 0x15e8988}
>> (gdb) p *rtable->head->next->next
>> $13 = {data = {ptr_value = 0x15e89a8, int_value = 22972840, oid_value =
>> 22972840}, next = 0x15e9018}
>> (gdb) p *rtable->head->next->next->next
>> $14 = {data = {ptr_value = 0x15e9038, int_value = 22974520, oid_value =
>> 22974520}, next = 0x15e9820}
>> (gdb) p *rtable->head->next->next->next->next
>> $15 = {data = {ptr_value = 0x15e9840, int_value = 22976576, oid_value =
>> 22976576}, next = 0x15e7998}
>> ===========================
>>
>> The line which starts with "$15" has 0x15e7998 as its next data.
>> But it is the head pointer(see the line which starts with $10).
>>
>> And in range_table_walker(), the function is called recursively.
>> --------
>> ...
>> if (!(flags & QTW_IGNORE_RANGE_TABLE))
>> {
>> if (range_table_walker(query->rtable, walker, context,
>> flags))
>> return true;
>> }
>> ...
>> --------
>>
>> We should make rtable right or deal with "flags" properly.
>> But I can't find where to do it...
>>
>> What do you think ?
>>
>> regards,
>> ---------
>> NTT Software Corporation
>> Tomonari Katsumata
>>
>>
>>
>>
>>
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>
>
>
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