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Re: [Postgres-xc-developers] Query Planning bug ?
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From: Tomonari K. <kat...@po...> - 2013-07-01 08:09:43
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Hi Ashutosh,
OK, I'll try regression test.
Please wait for the result.
regards,
------------
NTT Software Corporation
Tomonari Katsumata
(2013/07/01 17:06), Ashutosh Bapat wrote:
> Hi Tomonori,
>
>
>
> On Mon, Jul 1, 2013 at 1:33 PM, Tomonari Katsumata <
> kat...@po...> wrote:
>
>> Hi Ashutosh and all,
>>
>> Sorry for late response.
>> I made a patch for resolving the problem I mentioned before.
>>
>> I thought the reason of this problem is parsing query twice.
>> because of this, the rtable is made from same Lists and become
>> cycliced List.
>> I fixed this problem with making former List empty.
>>
>> I'm not sure this fix leads any anothre problems but
>> the problem query I mentioned before works fine.
>>
>> This patch is against for "**a074cac9b6b507e6d4b58c5004673f**6cc65fcde1".
>>
>>
> You can check the robustness of patch by running regression. Please let me
> know what you see.
>
>
>> regards,
>> ------------------
>> NTT Software Corporation
>> Tomonari Katsumata
>>
>>
>> (2013/06/17 18:53), Ashutosh Bapat wrote:
>>
>>> Hi Tomonari,
>>> In which function have you taken this debug info? What is list1 and list2?
>>>
>>>
>>> On Mon, Jun 17, 2013 at 10:13 AM, Tomonari Katsumata <
>>> kat...@po....**jp <kat...@po...>>
>>> wrote:
>>>
>>> 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....**jp<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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