Re: V8.4 TOAST table problem

Idle in Transaction? Or plain Idle? Idle in Transaction stops vacuum from
reclaiming space and is indicative of a broken application.

On Fri, Jul 12, 2013 at 9:39 AM, Bradley McCune <bradley(dot)mccune(at)noaa(dot)gov>wrote:

> The only transactions present were "<IDLE>" for current_query. I even
> stopped the remote services, restarted the PostgreSQL server (assumingly,
> there should be no transactions occurring now), and performed another
> VACUUM FULL followed by REINDEX due to known fullvac index bloat in pre-9
> pgsql version.
>
>
> On Fri, Jul 12, 2013 at 11:28 AM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>wrote:
>
>> Did you have a long running trasnaction? Especially a prepared
>> transaction, blocking the vacuum from reclaiming the space?
>>
>> On Fri, Jul 12, 2013 at 8:10 AM, Bradley McCune <bradley(dot)mccune(at)noaa(dot)gov>
>> wrote:
>> > David,
>> >
>> > (As a preface, I have already gone forward with completely rebuilding
>> the
>> > database which seems to have finally fixed the problem. Rebuilding the
>> > table itself had no effect, and I couldn't wait much longer to move
>> > forward.)
>> >
>> > Yes, this seems similar, however, the key difference being that VACUUM
>> FULL
>> > did not alleviate the problem. The extra "bloated" disk space was still
>> > considered "in use" by the data server, and so it was never returned to
>> the
>> > system. I have a suspicion that the server was storing the table data
>> in
>> > pages in an inefficient manner (by unknown means) because we had
>> roughly ~5x
>> > the number of pages used on that TOAST table to store the same number of
>> > tuples compared to other similar databases.
>> >
>> > Depending on how often you have to use VACUUM FULL, you might want to
>> > consider tweaking the autovacuum to be more aggressive on that hot
>> table to
>> > keep it in check more often. (Recycling the disk space more efficiently
>> > rather than sending it back to the server only to be reallocated to the
>> > database again.)
>> >
>> >
>> > On Fri, Jul 12, 2013 at 4:09 AM, David Welton <davidw(at)dedasys(dot)com>
>> wrote:
>> >>
>> >> Hi,
>> >>
>> >> I have a very similar problem... details below.
>> >>
>> >> On Wed, Jul 3, 2013 at 5:19 PM, Paul Tilles <paul(dot)tilles(at)noaa(dot)gov>
>> wrote:
>> >> > Recently, I've had a PostgreSQL 8.2.11 server upgraded to 8.4 in
>> order
>> >> > to
>> >> > take advantage of autovacuum features. This server exists in a very
>> >> > closed
>> >> > environment (isolated network, limited root privileges; this explains
>> >> > the
>> >> > older software in use) and runs on RHEL5.5 (i686). After the upgrade,
>> >> > the
>> >> > database has constantly been growing to the tune of 5-6 GB a day.
>> >> > Normally,
>> >> > the database, as a whole, is ~20GB; currently, it is ~89GB. We have a
>> >> > couple
>> >> > other servers which run equivalent databases and actually synchronize
>> >> > the
>> >> > records to each other via a 3rd party application (one I do not have
>> >> > access
>> >> > to the inner workings). The other databases are ~20GB as they should
>> be.
>> >>
>> >> Our machine is an Ubuntu 12.04 system running on AWS, so it's a 64 bit
>> >> system:
>> >>
>> >> PostgreSQL 9.1.9 on x86_64-unknown-linux-gnu, compiled by gcc
>> >> (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3, 64-bit
>> >>
>> >> > Running the following SQL, it's fairly obvious there's an issue with
>> a
>> >> > particular table, and, more specifically, its TOAST table.
>> >>
>> >> Same thing here: we have a table with around 2-3 megs of data that is
>> >> blowing up to *10 gigs*.
>> >>
>> >> > This TOAST table is for a table called "timeseries" which saves large
>> >> > records of blobbed data. ASUM(LENGTH(blob)/1024./1024.) of all the
>> >> > records
>> >> > in timeseries yields ~16GB for that column. There should be [b]no
>> >> > reason[/b]
>> >> > this table's TOAST table should be as large as it is.
>> >>
>> >> Similar situation: it's a bytea column that gets "a lot" of updates;
>> >> in the order of 10's of thousands a day.
>> >>
>> >> > I've performed a VACUUM FULL VERBOSE ANALYZE timeseries, and the
>> vacuum
>> >> > runs
>> >> > to completion with no errors.
>> >>
>> >> VACUUM FULL fixes the problem for us by recouping all the wasted disk
>> >> space. I don't have the knowledge to investigate much further on my
>> >> own, but I'd be happy to try out a few things. The database is,
>> >> unfortunately, sensitive data that I can't share, but I could probably
>> >> script a similar situation...
>> >>
>> >> --
>> >> David N. Welton
>> >>
>> >> http://www.dedasys.com/
>> >
>> >
>> >
>> >
>> > --
>> > Bradley D. J. McCune
>>
>>
>>
>> --
>> To understand recursion, one must first understand recursion.
>>
>
>
>
> --
> Bradley D. J. McCune
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> Community Hydrologic Prediction System - Support
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>
>

--
To understand recursion, one must first understand recursion.