On Wed, Sep 24, 2014 at 2:35 PM, <christian.echerer@xxxxxxxxxxxxxxxxx> wrote:
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
I suspect that this kind of errors occur due to less size of shared_buffer,work_mem and maintenance_work_mem.
Solution to resolve this kind of errors , by increasing the size of shared_buffers ,work_mem and maintenance_work_mem.
As your RAM is 8 GB , try to perform base-backup by setting the parameters in postgresql.conf as given shared_buffers=(app 1GB to 2GB),work_mem=512MB,maintenance_work_mem=512MB.
This might resolve your issue of pg_basebackup.
Regards,
Chetan Sharma,
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