[Postgres-xl-bugs] Errors due to autovacuum?

Agoston David asvany at gmail.com
Wed Mar 16 03:49:43 PDT 2016


Thanks this workaround. Disabling the autovacuum process keeps the system
 in stable state, and I can run VACUUM manually at night.

,asvany

On Thu, Mar 10, 2016 at 4:07 PM user <susernameb at gmail.com> wrote:

> The oid corresponds to a relation we created. It does not correspond to a
> system catalog.
>
>
>
> There are two errors that happens occasionally :
>
> “could not find tuple for relation 23269”
>
> “catalog is missing 3 attribute(s) for relid 22796”
>
>
>
> Further information:
>
> -          Our setup has only one coordinator and one datanode.
>
> -          We are using commit “e1d06bdacf69954f1b81eeb84a42fe13b51fe44c”
>
> -          Oids 23269 and 22796 correspond to  relations we create, not
> to system catalogs.
>
> -          The error messages appear in coordinator log, not in datanode
> log.
>
> -          Oid 23269 exists in pg_class on datanode
>
> -          Oid 23269 does not exists in pg_class on coordinator
>
> -          No ALTER TABLE statement is ever issued.
>
>
>
> Autovacuum logging:
>
> The errors sometimes occur immediately after vacuum, but not always.
>
>
>
> We create tables in two ways
>
> 1.       Issuing CREATE TABLE via libpq to the coordinator
>
> 2.       Issuing CREATE TABLE from plpgsql functions.
>
> Errors occur for both 1 and 2 above.
>
> No ALTER TABLE statement is ever issued.
>
>
>
> Do let me know if you need any more info.
>
>
>
> Thanks!
>
>
>
> *From:* Pavan Deolasee [mailto:pavan.deolasee at gmail.com]
> *Sent:* Wednesday, March 09, 2016 11:18 PM
> *To:* user
> *Cc:* postgres-xc-bugs
> *Subject:* Re: [Postgres-xl-bugs] Errors due to autovacuum?
>
>
>
>
>
>
>
> On Thu, Mar 10, 2016 at 3:51 AM, user <susernameb at gmail.com> wrote:
>
> Hi,
>
>
>
> Continuing using XL, we found two issues as listed below.
>
>
>
> 1.       The following error keeps poping up in the coordinator log for
> different relations.
>
> “catalog is missing 3 attribute(s) for relid 23307”
>
>
>
>  Can you please check and tell us what the oid 23307 corresponds to? I
> suspect if its one of the system catalogs.
>
>
>
> 2.       Also, after create table is issued to coordinator, a select etc
> on table says “table does not exist”
>
> The new table can be seen in pg_class on datanode. But the new table does
> not exists in pg_class on coordinator.
>
>
>
> Do you create these tables via DDLs issued via psql command line or some
> different mechanism (like from plpgsql function)? Also, I assume you are
> running the latest sources from XL9_5_STABLE branch. If not, please let us
> know.
>
>
>
> Do you also do frequent ALTER TABLE?
>
>
>
>
>
> BOTH OF THE ABOVE ERRORS HAPPEN NON-DETERMINISTICALLY – sometimes they do
> at different points in the test run, sometimes they don’t.
>
>
>
> Since the errors are not perfectly repeatable, we suspected this was due
> to interference between multiple XL processes.
>
> To try out, we disabled the autovacuum launcher process. Basically, made
> StartAutoVacLauncher() in autovaccuum.c do nothing.
>
>
>
> “Once autovacuum launcher was disabled, the errors disappeared too.”
>
>
>
> Thanks for the clue. You could have also turned autovacuum off which would
> have the same effect. Can you please turn autovacuum logging on and see if
> the error occurs immediately after a vacuum is run?
>
>
> Thanks,
>
> Pavan
>
>
>
> --
>
>  Pavan Deolasee                   http://www.2ndQuadrant.com/
>  PostgreSQL Development, 24x7 Support, Training & Services
>
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