Thread: CLUSTER using more memory than expected

The CLUSTER function seems to be using more memory than I expect.  Here is what I get from top and from my config file:

from top:
27589 postgres  25   0 3943m 3.6g  11m R 99.9 61.6 639:19.41 postgres: postgres data 127.0.0.1(42126) CLUSTER

from postgresql.conf
shared_buffers = 1000 #26214            # min 16, at least max_connections*2, 8KB each
work_mem = 256000               # min 64, size in KB
maintenance_work_mem = 2097151  # min 1024, size in KB
#max_stack_depth = 2048         # min 100, size in KB

My version is: 8.0.3

Any ideas why this would be happening.  I tried a full restart and the same thing happens.

Thanks,

Josh


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"Joshua Marsh" <icub3d@gmail.com> writes:
> The CLUSTER function seems to be using more memory than I expect.

CLUSTER will eat maintenance_work_mem during index rebuilds --- more or
less.  You shouldn't expect these numbers to be dead on, particularly
not in older releases.  It looks like your 2Gb spec has turned into
3.6Gb actually eaten, which is a bit sloppier accounting than I'd like
but not overly surprising.  (FWIW, I think CVS HEAD is better than 8.0
at measuring sort workspace.)

            regards, tom lane

Thanks for the clarification.  It doesn't sound like it's going to jump to 8Gb and hog most of the RAM.

On Wed, Oct 25, 2006 at 10:13:59AM -0600, Joshua Marsh wrote:
> My version is: 8.0.3

You should really upgrade to 8.0.9; there's crash and data loss bugs
that have been fixed since 8.0.3.
--
Jim Nasby                                            jim@nasby.net
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)

Eeek!  Thanks for the head's up.  I'll do that.