Re: vacuum problem

John R Pierce wrote:

>>> About an hour after mailing that, I realized that the buggy RHEL2.1
>>> system was running with Intel Hyperthreading enabled (so it appeared
>>> as 4 CPUs) while the no-problems RH8.0 system had hyperthreading
>>> enabled (we'd previously been benchmarking some multithreaded stuff
>>> both ways). So, its *just* possible that the earlier RHEL2.1
>>> (kernel 2.4.9-e.43enterprise) had issues which the later RH8
>>> (2.4.20-28.8smp) were resolved. I'll not be able to test this
>>> hypothesis until monday morning.
>>
>>
>> I run RHEL2.1 on the same your HW with HT enabled and I never had a
>> problem
>> with that.
>
>
> are you running PGSql 7.4.x ? (we have this same issue with 7.4.2 and
> 7.4.5). fyi, my RHEL2.1 has all available up2date fixes, and I did
> *NOT* install RH's postgres RPM, rather, I fetched and built 7.4.5 from
> source

I was running 7.4.2 and since 3 weeks we are running a 7.4.5
Suddenly after the upgrade an ill coded servlets ( in place long time )
started to drive Postgres to PANIC; now the servlet is fixed and the
problem disappeared. See my post: "invalid string enlargement". Tom Lane
also was able to reproduce it and I bet already he fixed the problem.

> could you perhaps give my test program a try? create a database
> 'test', a user 'test' with password 'test', and table 'test' as
> described in my original message, and compile and run this program:
>
> http://www.hogranch.com/files/PGTest.java
>
> compile the java program with Sun J2SE JDK 1.4.x..
>
> $ javac PGTest.java

Unfortunatelly I can not try it for two reasons: the machine is a
production machine and I can not use it for experiments and the other
reason is that our Java reference is the 1.3.x :-(

> (postgresql.jar has to be in your CLASSPATH, or you can specify it as
> -cp .:/path/postgresql.jar .. I'm using the one that compiled with 7.4.5
> and my jdk 1.4.x)

Which one ? I hope you are using pg74.213.jdbc3.jar

> I am unable to vacuum the freespace in this table until I stop and
> restart the postgresql service. put your autovacuum back online when
> you're done messing. I can not reproduce this problem on a RH8
> (2.4.20.x) system

Do you mean that is not enough stop your java application in order to
retrieve the space with a vacuum ? Do you have some connection in status:
"Idle in transaction" ?

Regards
Gaetano Mendola