Re: V8.4 TOAST table problem

Prepared transactions that are sitting still do the same thing, and show no
connections.

On Fri, Jul 12, 2013 at 2:25 PM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>wrote:

> 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
>> NOAA/OCWWS/HSD
>> Community Hydrologic Prediction System - Support
>> CHPS FogBugz Administrator
>> Office phone: (301) 713-1625 x160
>>
>>
>>
>
>
> --
> To understand recursion, one must first understand recursion.
>

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