I've had this problem a number of times.  Before I tell you what I did to
solve this problem, let me warn you that I am a novice at DBs (PostgreSQL is
my first database).

In my experience, the problem seems to be caused by a lot of data being put
into the database.  We are using the database to ingest real-time data 24
hours a day/7 days a week. The data comes in about every three minutes.
While I was not able to identify what the exact cause has been, I have
noticed that before the problem becomes critical (before the backend
terminates abnormally), the (number of) indexes do not correspond to the
actual table.  That leads me to believe that the indexes do not get created
on all occasions.  After some time, the table's internal indexes may be come
corrupted, and vacuuming does no good.

When trying to fix this, I first delete the index, then recreate it., then
vacuum.  If that doesn't work, then I drop the table, create the index,
reload the data, and then vacuum the table.

I would be curious to see if anyone else has had this type of problem and
what their solutions were.

I can provide the scripts to check the database to the newsgroup or to you
directly, if desired.

David


-----Original Message-----
From: Sferacarta Software <sferac@bo.nettuno.it>
To: pgsql-general@postgreSQL.org <pgsql-general@postgreSQL.org>
Date: Friday, August 21, 1998 10:57 AM
Subject: [GENERAL] DELETE statement KILL backend <AGAIN>


>
> Hello all,
>
> I have a strange problem that I can't understand.
> I have been my PostgreSQL-6.3.2 on Linux-ELF-2.0.34 working without any
problem for many
> months. This morning I can't DELETE anymore.
> If I try to delete a row from any table I have this message:
>
> PGexec() -- Request has sent to backend, but backend closed the
> channel before responding.
> This probably means the backend terminated abnormally before or while
> processing the request.
>
> and then the backend dies.
>
> I tried every statement as:
> INSERT
> UPDATE
> SELECT
> DROP TABLE
> and all of them works but DELETE,
>
> I tried also VACUUM without success.
>
> PLEASE help me !!
>
> Best regards,
>    Jose'                          mailto:sferac@bo.nettuno.it
>
>
>


Fri, 21 Aug 1998 17:01:25 -0500
"David Ben-Yaacov" <David_BenYaacov@itd.sterling.com>
Re: [GENERAL] DELETE statement KILL backend <AGAIN>
Hello David,

Thanks to reply to my answer.

DBY> I've had this problem a number of times.  Before I tell you what I did to
DBY> solve this problem, let me warn you that I am a novice at DBs (PostgreSQL is
DBY> my first database).

DBY> In my experience, the problem seems to be caused by a lot of data being put
DBY> into the database.
Unfortunately this isn't my case.
DBY> We are using the database to ingest real-time data 24
DBY> hours a day/7 days a week. The data comes in about every three minutes.
DBY> While I was not able to identify what the exact cause has been, I have
DBY> noticed that before the problem becomes critical (before the backend
DBY> terminates abnormally), the (number of) indexes do not correspond to the
DBY> actual table.  That leads me to believe that the indexes do not get created
DBY> on all occasions.  After some time, the table's internal indexes may be come
DBY> corrupted, and vacuuming does no good.
I have this problem on every table, those with index and those
without.

Right now, if I create a table without indexes and then I "DELETE FROM
table" the backend dies immediately.

DBY> When trying to fix this, I first delete the index, then recreate it., then
DBY> vacuum.  If that doesn't work, then I drop the table, create the index,
DBY> reload the data, and then vacuum the table.

DBY> I would be curious to see if anyone else has had this type of problem and
DBY> what their solutions were.
Me too.

DBY> I can provide the scripts to check the database to the newsgroup or to you
DBY> directly, if desired.
I'm not sure if this can solve my problem, anyway send me it.
Thanks for all,
Jose'

DBY> -----Original Message-----
DBY> From: Sferacarta Software <sferac@bo.nettuno.it>
DBY> To: pgsql-general@postgreSQL.org <pgsql-general@postgreSQL.org>
DBY> Date: Friday, August 21, 1998 10:57 AM
DBY> Subject: [GENERAL] DELETE statement KILL backend <AGAIN>


>>
>> Hello all,
>>
>> I have a strange problem that I can't understand.
>> I have been my PostgreSQL-6.3.2 on Linux-ELF-2.0.34 working without any
DBY> problem for many
>> months. This morning I can't DELETE anymore.
>> If I try to delete a row from any table I have this message:
>>
>> PGexec() -- Request has sent to backend, but backend closed the
>> channel before responding.
>> This probably means the backend terminated abnormally before or while
>> processing the request.
>>
>> and then the backend dies.
>>
>> I tried every statement as:
>> INSERT
>> UPDATE
>> SELECT
>> DROP TABLE
>> and all of them works but DELETE,
>>
>> I tried also VACUUM without success.
>>
>> PLEASE help me !!
>>
>> Best regards,
>>    Jose'                          mailto:sferac@bo.nettuno.it
>>
>>
>>




Best regards,
 Sferacarta                            mailto:sferac@bo.nettuno.it



Mon, 24 Aug 1998 09:54:23 +0200
Sferacarta Software <sferac@bo.nettuno.it>
Re[2]: [GENERAL] DELETE statement KILL backend <AGAIN>