Hello Vladimir,
maybe your update triggered auto_vacuum on those tables ? Default
autovacuum_freeze_max_age is exactly set at 200,000,000 . Did you check your
vacuum stats afterwards (pg_stat_*_tables) ?
Can you show the code which performed the deletes?
On 10/10/2017 16:56, Vladimir Nicolici
I experimented some more with the settings this weekend, while doing some large
write operations (deleting 200 million records from a table), and I realized
that the database is capable of generating much more WAL than I estimated.
And it seems that spikes in write activity, when longer than a f
Further updates:
Yesterday checkpoints were finishing more or less on time with the
configuration for 25 minutes out of 30 minutes, taking 26 minutes at most.
So for today I reduced the time reserved for checkpoint writes to 20 minutes
out of 30 minutes, by setting checkpoint_completion_target
Hi,
On 2017-10-05 22:58:31 +0300, Vladimir Nicolici wrote:
> I changed some configuration parameters during the night to the values I was
> considering yesterday:
>
> - shared_buffers = 144GB #previously 96 GB
> - bgwriter_lru_maxpages = 100 #previously 400
> - checkpoint_timeout = 30min #prev
Vladimir,
Just curious, if your goal is to reduce checkpoint overhead, shouldn’t you
decrease shared_buffers instead of increasing it?
With bigger shared_buffers, you can accumulate more dirty buffers for
checkpoint to take care.
I remember in early versions ( around 8.4), when checkpoint_compl
Some further updates about the issue.
I did a bit of benchmarking on the disk system with iozone, and the during the
test the SSDs seemed to be able to easily sustain 200 MB/second of writes each,
they fluctuated between 200 MB/s and 400 MB/s when doing 96 GB of random writes
in a file. That wo
I have a large database, 1.3 TB, with quite a bit of write activity. The
machine has, 2 cpus x 6 cores x 2 threads (2 x E5-2630 v2 @ 2.60GHz), 4 x EVO
Pro 2TB SSDs in a RAID 1+0 software raid configuration, on a SATA 3 controller.
The machine has a lot of memory, 384 GB, so it doesn’t do a lot o
