Обсуждение: pg_restore takes more time on creation of rules

On Wed, May 22, 2019 at 06:26:49PM +0300, Mariel Cherkassky wrote:
>Hey,
>I'm trying to restore a cluster (9.2) from 3 binary dumps (pg_dump -Fc).
>Each dump contains only one database.
>The sizes :
>A-10GB
>B-20GB
>C-5GB.
>
>For unclear reason the restore of the third database is taking alot of
>time. It isnt stuck but it continues creating db rules. This database has
>more then 400K rules.
>

What do you mean by "rules"?

>I changed a few postgresql.conf parameters :
>shared_buffers = 2GB
>effective_cache_size = 65GB
>checkpoint_segments =20
>checkpoint_completion_target = 0.9
>maintenance_work_mem = 10GB
>checkpoint_timeout=30min
>work_mem=64MB
>autovacuum = off
>full_page_writes=off
>wal_buffers=50MB
>
>my machine has 31 cpu and 130GB of ram.
>
>Any idea why the restore of the two dbs takes about 15 minutes while the
>third db which is the smallest takes more than 1 hour ?  I restore the
>dump with pg_restore with 5 jobs (-j).
>

Well, presumably the third database has complexity in other places,
possibly spending a lot of time on CPU, while the other databases don't
have such issue.

What would help is a CPU profile, e.g. from perf.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

On Wed, May 22, 2019 at 06:26:49PM +0300, Mariel Cherkassky wrote:
>Hey,
>I'm trying to restore a cluster (9.2) from 3 binary dumps (pg_dump -Fc).
>Each dump contains only one database.
>The sizes :
>A-10GB
>B-20GB
>C-5GB.
>
>For unclear reason the restore of the third database is taking alot of
>time. It isnt stuck but it continues creating db rules. This database has
>more then 400K rules.
>

What do you mean by "rules"?

>I changed a few postgresql.conf parameters :
>shared_buffers = 2GB
>effective_cache_size = 65GB
>checkpoint_segments =20
>checkpoint_completion_target = 0.9
>maintenance_work_mem = 10GB
>checkpoint_timeout=30min
>work_mem=64MB
>autovacuum = off
>full_page_writes=off
>wal_buffers=50MB
>
>my machine has 31 cpu and 130GB of ram.
>
>Any idea why the restore of the two dbs takes about 15 minutes while the
>third db which is the smallest takes more than 1 hour ?  I restore the
>dump with pg_restore with 5 jobs (-j).
>

Well, presumably the third database has complexity in other places,
possibly spending a lot of time on CPU, while the other databases don't
have such issue.

What would help is a CPU profile, e.g. from perf.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

On Wed, May 22, 2019 at 06:44:29PM +0300, Mariel Cherkassky wrote:
>By rules I mean DB rules (simillar to triggers but different)
>

I very much doubt such high number of rules was expected during the
design (especially if it's on a single table), so perhaps there's an
O(N^2) piece of code somewhere. I suggest you do a bit of profiling, for
example using perf [1], which would show where the time is spent.

[1] https://wiki.postgresql.org/wiki/Profiling_with_perf

And please stop top-posting, it makes it much harder to follow the
discussion.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

On Wed, May 22, 2019 at 06:44:29PM +0300, Mariel Cherkassky wrote:
>By rules I mean DB rules (simillar to triggers but different)
>

I very much doubt such high number of rules was expected during the
design (especially if it's on a single table), so perhaps there's an
O(N^2) piece of code somewhere. I suggest you do a bit of profiling, for
example using perf [1], which would show where the time is spent.

[1] https://wiki.postgresql.org/wiki/Profiling_with_perf

And please stop top-posting, it makes it much harder to follow the
discussion.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services