[pgpool-general: 3652] Re: Error in pgpool memory cache invalidation.

[Muhammad Usama]

Hi

I have found the problem, It was because of the buffer for storing table
oids was created in wrong memory context.
I have pushed the fix for it in master and 3_4 stable branches.

Thanks
Best regards
Muhammad Usama


On Wed, Apr 22, 2015 at 2:09 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:

> Thanks for the report.
>
> I confirm this with pgpool-II 3.4.1. I also found that this does not
> happen with 3.3.5 (I tested with shmem).
>
> Here is the test script.
> -------------------------------------
> drop table t1;
> create table t1(i int, j text);
> insert into t1 values(1, 'aaa');
> select * from t1;
> select * from t1;
> update t1 set j = 'bbb' where i = 1;
> select * from t1;
> -------------------------------------
>
> Will look into this...
>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
>
> > Looks like only part of this email ended up in the mailing list , not
> > sure how. Resending again - hope it works this time.
> >
> > pgpool doesn't seem to be invalidating caches properly. See the
> > example test case below
> >
> > psql -U ruser -d mydb -h 127.0.0.1 -p 9999
> > Password for user ruser:
> > psql (9.4.1)
> > Type "help" for help.
> >
> > mydb=> select comments from users where id=1;
> >  comments
> > ----------
> >  boooo
> > (1 row)
> >
> > # comes from cache
> > mydb=> select comments from users where id=1;
> >  comments
> > ----------
> >  boooo
> > (1 row)
> >
> > # works
> > mydb=> update users set comments='hello' where id=1;
> > UPDATE 1
> > mydb=> select comments from users where id=1;
> >  comments
> > ----------
> >  hello
> > (1 row)
> >
> > # stale
> > mydb=> update users set comments='hello world' where id=1;
> > UPDATE 1
> > mydb=> select comments from users where id=1;
> >  comments
> > ----------
> >  hello
> > (1 row)
> >
> > # also stale
> > mydb=> update users set comments='booo' where id=1;
> > UPDATE 1
> > mydb=> select comments from users where id=1;
> >  comments
> > ----------
> >  hello
> > (1 row)
> >
> >
> > From the second write onwards, the cache is not invalidated and stale
> > value is being served. Is it a bug or am I doing something wrong? This
> > happens with both cache backends (memcache and shmem but test logs are
> > from memcache backend)
> >
> > Test setup is postgresql-9.4 and memcached 1.4.21 and pgpool-3.4.2. my
> > configs and logs from test are here
> >
> > https://gist.github.com/dbalan/d635993a3e532a083751
> >
> > Regards,
> > --------
> > DHANANJAY | Infrastructure Engineer
> > Plivo, Inc. 340 Pine St, San Francisco - 94104, USA
> > Web: www.plivo.com | Twitter: @plivo, @notmycommit
> > DHANANJAY | Infrastructure Engineer
> > Plivo, Inc. 340 Pine St, San Francisco - 94104, USA
> > Web: www.plivo.com | Twitter: @plivo, @notmycommit
> >
> > Free Incoming SMS for All US Short Codes – Get One Today!
> >
> >
> >
> >
> > On Tue, Apr 21, 2015 at 12:33 PM, Dhananjay Balan <dhananjay at plivo.com>
> wrote:
> >> pgpool doesn't seem to be invalidating caches properly. See the
> >> example test case below
> >>
> >> psql -U ruser -d mydb -h 127.0.0.1 -p 9999
> >> Password for user ruser:
> >> psql (9.4.1)
> >> Type "help" for help.
> >>
> >> mydb=> select comments from users where id=1;
> >>  comments
> >> ----------
> >>  boooo
> >> (1 row)
> >>
> >> # comes from cache
> >> mydb=> select comments from users where id=1;
> >>  comments
> >> ----------
> >>  boooo
> >> (1 row)
> >>
> >> # works
> >> mydb=> update users set comments='hello' where id=1;
> >> UPDATE 1
> >> mydb=> select comments from users where id=1;
> >>  comments
> >> ----------
> >>  hello
> >> (1 row)
> >>
> >> # stale
> >> mydb=> update users set comments='hello world' where id=1;
> >> UPDATE 1
> >> mydb=> select comments from users where id=1;
> >>  comments
> >> ----------
> >>  hello
> >> (1 row)
> >>
> >> # also stale
> >> mydb=> update users set comments='booo' where id=1;
> >> UPDATE 1
> >> mydb=> select comments from users where id=1;
> >>  comments
> >> ----------
> >>  hello
> >> (1 row)
> >>
> >>
> >> From the second write onwards, the cache is not invalidated and stale
> >> value is being served. Is it a bug or am I doing something wrong? This
> >> happens with both cache backends (memcache and shmem but test logs are
> >> from memcache backend)
> >>
> >> Test setup is postgresql-9.4 and memcached 1.4.21 and pgpool-3.4.2. my
> >> configs and logs from test are here
> >>
> >> https://gist.github.com/dbalan/d635993a3e532a083751
> >>
> >> Regards,
> >> --------
> >> DHANANJAY | Infrastructure Engineer
> >> Plivo, Inc. 340 Pine St, San Francisco - 94104, USA
> >> Web: www.plivo.com | Twitter: @plivo, @notmycommit
> > _______________________________________________
> > pgpool-general mailing list
> > pgpool-general at pgpool.net
> > http://www.pgpool.net/mailman/listinfo/pgpool-general
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