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Re: [Postgres-xc-developers] Query Planning bug ?
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From: Ashutosh B. <ash...@en...> - 2013-06-17 09:53:43
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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...> 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...> 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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--
Best Wishes,
Ashutosh Bapat
EntepriseDB Corporation
The Postgres Database Company
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