Hi,
while creating a backup with pg_dump and parallel write accesses to the database following error occured:
2014-09-24 07:46:46 ... ERROR: out of shared memory
2014-09-24 07:46:46 ... HINT: You might need to increase max_pred_locks_per_transaction.
I´m running postgresql 9.3.4 on Ubuntu 12.04 server. The server has 8GB RAM and 4 cores.
/proc/sys/kernel/shmmax: 2147483648
/proc/sys/kernel/shmall: 2097152
The original configuration was changed in only a few relevant points:
* shared_buffers = 128MB
* work_mem = 10MB
We run a hot standby slave, therefore the following changes were necessary:
* wal_level = hot_standby
* max_wal_senders = 1
* wal_keep_segments = 64
* hot_standby = on
* hot_standby_feedback = on
I didn´t understand the HINT:
You might need to increase max_pred_locks_per_transaction.
What is the reason for the error, that the shared memory ran out, or that the number of predicate locks is too small?
If i increase max_pred_locks_per_transaction i get probably even faster an "out of shared memory" error.
What is the best way to fix the problem?
The database consists of approximately 150 tables and is about 140GB in size. Where one table with 130 GB (~280000000
rows)requires the most space.
Please help me to troubleshoot this severe problem. I will feedback any required information.
Thanks in advance
Christian
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