Thread: _penalty gist method invoked with one key NULL

_penalty gist method invoked with one key NULL

From
Grzegorz Piotr Jaskiewicz
Date:
As in subject.
What it does, it gets through picksplit, I return good values, valid unions,
etc. Than (I guess) postgres is trying to insert another value in tree, hence
penalty is called. Why one of the values penalty is called with is NULL, and
I have no idea if that's valid.
From all the examples available in contrib dir, I can deduct that it shouldn't
happend.
Now question, how shall I debug postgres in this case?
can I just run postgres, in non forking mode, on gdb?
I am running psql with all commands required to create new type, functions,
operators, and gist. So there must be separate connection available for that.

Thanks.

--
GJ

Binary system, you're either 1 or 0...
dead or alive ;)


Re: _penalty gist method invoked with one key NULL

From
Tom Lane
Date:
Grzegorz Piotr Jaskiewicz <gj@pointblue.com.pl> writes:
> can I just run postgres, in non forking mode, on gdb?

Just start a normal session and then attach to the backend process with
gdb in a separate window.  There's no reason to fool with a standalone
backend for 99.99% of debugging problems.  With a regular session, you
can use psql to input the SQL commands, which is MUCH friendlier than a
standalone backend, and you can run additional sessions in case you'd
like to examine the state of the database while you've got your debug
backend pinned down someplace.

I tend to use the attached script so that I don't even need to manually
discover the PID to attach to, assuming there's only one backend running
(else it shows me all the plausible candidates to attach to).

Dunno about the gist-specific issue, Oleg or Teodor will have to answer
that.
        regards, tom lane

#!/bin/sh

# Usage: gdblive

# tee /dev/tty is for user to see the set of procs considered
PROCS=`ps auxww | \   grep postgres: | \   grep -v -e 'grep postgres:' -e 'postgres: stats' -e 'postgres: writer' -e
'postgres:archiver' -e 'postgres: logger' | \   tee /dev/tty | \   awk '{print $2}'`
 

if [ `echo "$PROCS" | wc -w` -eq 1 ]
then   exec gdb $PGINSTROOT/bin/postgres -silent "$PROCS"
else   exec gdb $PGINSTROOT/bin/postgres -silent
fi


Re: _penalty gist method invoked with one key NULL

From
gj
Date:
Ok, Thanks for that. Script works great.
Here's bt I get:
#0  0xb7ef26a4 in ?? ()
#1  0xb7cae460 in _IO_list_all () from /lib/tls/libc.so.6
#2  0xb7ef2ea8 in ?? ()
#3  0x00000000 in ?? ()
#4  0x0844bebc in ?? ()
#5  0x00000000 in ?? ()
#6  0xb7cadff4 in ?? () from /lib/tls/libc.so.6
#7  0xb7cadff4 in ?? () from /lib/tls/libc.so.6
#8  0x08432746 in ?? ()
#9  0xbfc24eb0 in ?? ()
#10 0xbfc252d4 in ?? ()
#11 0xbfc24fd4 in ?? ()
#12 0xbfc24fb0 in ?? ()
#13 0x0844bebc in ?? ()
#14 0x00000000 in ?? ()
#15 0xbfc24cd0 in ?? ()
#16 0xb7cadff4 in ?? () from /lib/tls/libc.so.6
#17 0xbfc24fb0 in ?? ()
#18 0xbfc24fd4 in ?? ()
#19 0xbfc24ef8 in ?? ()
#20 0x082c0b1d in FunctionCall3 (flinfo=0xbfc24cf0, arg1=3083469667,
arg2=3083469667, arg3=3083469667) at fmgr.c:1179
#21 0x082c0b1d in FunctionCall3 (flinfo=0xbfc260e4, arg1=3217183444,
arg2=3217182676, arg3=3217182640) at fmgr.c:1179
#22 0x0808730d in gistpenalty (giststate=0xbfc254e4, attno=0, key1=0xbfc252d4,
isNull1=0 '\0', key2=0xbfc24fd4, isNull2=0 '\0',    penalty=0xbfc24fb0) at gistutil.c:821
#23 0x080868fd in gistchoose (r=0xb710039c, p=0xb739b0a0 "", it=0x844beb4,
giststate=0xbfc254e4) at gistutil.c:688
I guess, what's important is #22 with two keys, both NOT nulls.
It's not a secret how my _penalty function is defined:
CREATE OR REPLACE FUNCTION enum_penalty( internal, internal, internal) RETURNS internal AS 'enum2916', 'enum_penalty'
LANGUAGEC STRICT;  
and in C it looks like that:
PG_FUNCTION_INFO_V1(enum_penalty);
Datum enum_penalty(PG_FUNCTION_ARGS)
{ GISTENTRY *origentry = (GISTENTRY *) PG_GETARG_POINTER(0); GISTENTRY *newentry = (GISTENTRY *) PG_GETARG_POINTER(1);
float*result = (float *) PG_GETARG_POINTER(2); struct enumNumber *key; struct enumNumber* ud; float tmp1, tmp2; ud =
(structenumNumber*) DatumGetPointer(origentry->key); key = (struct enumNumber*) DatumGetPointer(newentry->key);  tmp2 =
((float)ud->eStart)*(1.5*(float)ud->percent);tmp1 = ((float)key->eStart)*(1.5*(float)key->percent);  *result = tmp1 -
tmp2;PG_RETURN_POINTER(result);  
}
for whatever reason here origentry->key is NULL.
--
GJ



Re: _penalty gist method invoked with one key NULL

From
gj
Date:
Breakpoint 1, gistpenalty (giststate=0xbfc254e4, attno=0, key1=0xbfc252d4,
isNull1=0 '\0', key2=0xbfc24fd4, isNull2=0 '\0',    penalty=0xbfc24fb0) at gistutil.c:821
821                     FunctionCall3(&giststate->penaltyFn[attno],
(gdb) p key1
$1 = (GISTENTRY *) 0xbfc252d4
(gdb) p key1->key
$2 = 0
(gdb) p key2->key
$3 = 138721324
Sorry, key1 and key2 are just GISTENTRY pointers.
so, as I can see this is NULL indeed, so my _penalty function is ok.



Re: _penalty gist method invoked with one key NULL

From
Grzegorz Jaskiewicz
Date:
Seems like decompress and compress were offending here, simply  
removing them from gist index create helped.
But, I still get on explain analyze that seqscan was used, rather  
than gist. Even tho ~ operator is defined for gist, and that seqscan  
is set to false.

On 2005-10-28, at 00:24, gj wrote:

>
>
> Breakpoint 1, gistpenalty (giststate=0xbfc254e4, attno=0,  
> key1=0xbfc252d4,
> isNull1=0 '\0', key2=0xbfc24fd4, isNull2=0 '\0',
>     penalty=0xbfc24fb0) at gistutil.c:821
> 821                     FunctionCall3(&giststate->penaltyFn[attno],
> (gdb) p key1
> $1 = (GISTENTRY *) 0xbfc252d4
> (gdb) p key1->key
> $2 = 0
> (gdb) p key2->key
> $3 = 138721324
>
>
> Sorry, key1 and key2 are just GISTENTRY pointers.
> so, as I can see this is NULL indeed, so my _penalty function is ok.
>
>
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SOLVED Re: _penalty gist method invoked with one key NULL

From
Grzegorz Jaskiewicz
Date:
Sorry for all this crap, this is bullocks.
reason was, one of internal functions didn't filled out length value,  
and since the type is variable length, we had trouble.
Postgres wasn't copying anything, since length was 0, hence the NULL - >key.
So here's little request. Could someone please put ASSERT somewhere  
that would make it visible to ppl that are as stupid as me, and  
forgot to fill that field out?
Would be great, me myself I have no idea where it should go really.

Thanks again.

p.s.. yeah, good docs on gist are still missing, I mean tutorial, or  
really really good docs.
I have to thank here to AndrewSN for all the help, and have enough  
patience to help me, even through I sometimes ask too many stupid  
questions, or simply try to do stuff my way, rather than use his very  
good suggestions. Thank You.

-- 
GJ


Re: SOLVED Re: _penalty gist method invoked with one key

From
Christopher Kings-Lynne
Date:
Grzegorz - it'd be great if you submitted documentation improvements :)

Grzegorz Jaskiewicz wrote:
> Sorry for all this crap, this is bullocks.
> reason was, one of internal functions didn't filled out length value,  
> and since the type is variable length, we had trouble.
> Postgres wasn't copying anything, since length was 0, hence the NULL - 
>  >key.
> So here's little request. Could someone please put ASSERT somewhere  
> that would make it visible to ppl that are as stupid as me, and  forgot 
> to fill that field out?
> Would be great, me myself I have no idea where it should go really.
> 
> Thanks again.
> 
> p.s.. yeah, good docs on gist are still missing, I mean tutorial, or  
> really really good docs.
> I have to thank here to AndrewSN for all the help, and have enough  
> patience to help me, even through I sometimes ask too many stupid  
> questions, or simply try to do stuff my way, rather than use his very  
> good suggestions. Thank You.
> 



Re: SOLVED Re: _penalty gist method invoked with one key

From
Oleg Bartunov
Date:
On Fri, 28 Oct 2005, Christopher Kings-Lynne wrote:

> Grzegorz - it'd be great if you submitted documentation improvements :)

I don't see any GiST specific problem in Grzegorz's case.

>
> Grzegorz Jaskiewicz wrote:
>> Sorry for all this crap, this is bullocks.
>> reason was, one of internal functions didn't filled out length value,  and 
>> since the type is variable length, we had trouble.
>> Postgres wasn't copying anything, since length was 0, hence the NULL - 
>> >key.
>> So here's little request. Could someone please put ASSERT somewhere  that 
>> would make it visible to ppl that are as stupid as me, and  forgot to fill 
>> that field out?
>> Would be great, me myself I have no idea where it should go really.
>> 
>> Thanks again.
>> 
>> p.s.. yeah, good docs on gist are still missing, I mean tutorial, or 
>> really really good docs.
>> I have to thank here to AndrewSN for all the help, and have enough 
>> patience to help me, even through I sometimes ask too many stupid 
>> questions, or simply try to do stuff my way, rather than use his very  good 
>> suggestions. Thank You.
>> 
>
>
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> TIP 5: don't forget to increase your free space map settings
>
    Regards,        Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83


Re: SOLVED Re: _penalty gist method invoked with one key

From
Grzegorz Jaskiewicz
Date:
On 2005-10-28, at 07:37, Oleg Bartunov wrote:

> On Fri, 28 Oct 2005, Christopher Kings-Lynne wrote:
>
>
>> Grzegorz - it'd be great if you submitted documentation  
>> improvements :)
>>
>
> I don't see any GiST specific problem in Grzegorz's case.
>
Other than just stupid bug, I know. It was just hard to find.  
Luckily, I have test cases for internal functions. This is separate  
program, that I can valgrind (me hugs valgrind).
Valgrind showed me that there is branch based on not initialized  
value. So I thought, maybe also length isn't initialized there, and I  
was right.
So, here's a tip from me: if your type has variable length, create  
separate function to locate all memory, and to fill out all fields.  
In my case it was possible, and helped.

Where is about docs, yes, I do plan to put out some tut based on my  
experiences. I will definitely give it to you guys to review here.

Thanks.