0ut of Memory Error during Vacuum Analyze

This is the second time I'm getting out of memory error when I start a
database vacuum or try to vacuum any table. Note this machine has been
used for data load batch purposes.

=# vacuum analyze code;
ERROR: out of memory
DETAIL: Failed on request of size 1073741820.

I'm running Postgres 8.1.1 on RedHat 2.6 kernel (HP server).
My maintenance work area never been changed. It's set to 1GB.
(maintenance_work_mem = 1048576). Physical memory: 32 GB.

Bouncing the database does not help.

Two workarounds I have used so far:

1) Decreasing the maintenance_work_mem to 512MB, vacuum analyze would
work just fine.

Or

2) Bouncing the server (maintaining the original 1GB
maintenance_work_mem) would also work.

I have not had that error on the production instances (which are
identical copies of the loading instance) - only the loading instance..

Any explanation as to why and how to avoid that ? Thanks

----

Husam
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