Re: requested shared memory size overflows size_t - Mailing list pgsql-hackers

From Yuri Levinsky
Subject Re: requested shared memory size overflows size_t
Date
Msg-id C9278837BA426D4DBDF8996DB8902326128E6C@Cobra.celltick.com
Whole thread Raw
In response to Re: requested shared memory size overflows size_t  (Heikki Linnakangas <hlinnakangas@vmware.com>)
Responses Re: requested shared memory size overflows size_t
List pgsql-hackers
Heikki,

I changed postgresql.conf to decrease those parameters but no change: GMT54000FATAL:  requested shared memory size
overflowssize_t 

> My kernel is:
> set semsys:seminfo_semmap=64
> set semsys:seminfo_semmni=4096
> set semsys:seminfo_semmns=4096
> set semsys:seminfo_semmnu=4096
> set semsys:seminfo_semume=64
> set semsys:seminfo_semmsl=500
> set shmsys:shminfo_shmmax=0xffffffffffff
> set shmsys:shminfo_shmmin=100
> set shmsys:shminfo_shmmni=4096
> set shmsys:shminfo_shmseg=100
>
shared_buffers = 5GB                    # min 16 or max_connections*2, 8KB each
temp_buffers = 256MB                    # min 100, 8KB each
max_prepared_transactions = 1000                # can be 0 or more
# note: increasing max_prepared_transactions costs ~600 bytes of shared memory
# per transaction slot, plus lock space (see max_locks_per_transaction).
# It is not advisable to set max_prepared_transactions nonzero unless you
# actively intend to use prepared transactions.
work_mem = 256MB                        # min 64, size in KB
maintenance_work_mem = 256MB            # min 1024, size in KB
max_stack_depth = 4MB
[L.Y.]

temp_buffers = 2GB seems very high. That settings is *per backend*, so if you have 10 backends that all use temporary
tables,they will consume 20GB altogether for temp buffers. work_mem works similarly, except that a single query can use
manytimes work_mem even in a single backend, so you need to be even more conservative with that. 1GB seems very high
forwork_mem. Try resetting these back to the defaults, and see if that works for you. Increase them gradually, and only
ifyou have a query where the higher value really helps. 

- Heikki




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