>
>Hm, well, given that you are able to capture instances of the behavior
>in EXPLAIN ANALYZE, I'd suggest trying EXPLAIN (ANALYZE,BUFFERS).
>That will tell you the number of pages it found in shared buffers vs.
>having to read them. Now, a "read" just means we had to ask the kernel,
>not necessarily that the page came all the way from disk; if it's in
>the kernel's disk cache that won't be very much slower than a shared-
>buffers hit. Still, if the slowdowns are reliably seen only when a read
>occurred, I'd say that's good evidence.
Well, that was a good thought - but:
Nested Loop (cost=0.00..4.20 rows=1 width=185) (actual time=567.113..567.113
rows=0 loops=1)
Join Filter: (be.branding_id = b.branding_id)
Rows Removed by Join Filter: 1
Buffers: shared hit=4
-> Nested Loop (cost=0.00..3.19 rows=1 width=189) (actual
time=567.081..567.092 rows=1 loops=1)
Join Filter: (s.setting_id = be.setting_id)
Rows Removed by Join Filter: 41
Buffers: shared hit=3
-> Seq Scan on branding_extension be (cost=0.00..1.00 rows=1 width=8)
(actual time=0.011..0.012 rows=1 loops=1)
Buffers: shared hit=1
-> Seq Scan on setting s (cost=0.00..2.04 rows=42 width=185) (actual
time=567.041..567.049 rows=42 loops=1)
Buffers: shared hit=2
-> Seq Scan on branding b (cost=0.00..1.01 rows=1 width=4) (actual
time=0.007..0.009 rows=1 loops=1)
Filter: ((name)::text = 'crs'::text)
Rows Removed by Filter: 1
Buffers: shared hit=1
Total runtime: 567.185 ms
I ran it several times and there were no reads, just shared hits, even on slow
executions.
It looks like it didn’t go out to the kernel for the data. I guess next steps
would be to adjust the deadlock_timeout? If I’m reading the docs correctly,
this doesn’t change how Postgres determines a deadlock, it just makes it check
for them sooner?
Thanks,
Scott
This email message contains information that Motus, LLC considers confidential
and/or proprietary, or may later designate as confidential and proprietary. It
is intended only for use of the individual or entity named above and should not
be forwarded to any other persons or entities without the express consent of
Motus, LLC, nor should it be used for any purpose other than in the course of
any potential or actual business relationship with Motus, LLC. If the reader of
this message is not the intended recipient, or the employee or agent
responsible to deliver it to the intended recipient, you are hereby notified
that any dissemination, distribution, or copying of this communication is
strictly prohibited. If you have received this communication in error, please
notify sender immediately and destroy the original message.
Internal Revenue Service regulations require that certain types of written
advice include a disclaimer. To the extent the preceding message contains
advice relating to a Federal tax issue, unless expressly stated otherwise the
advice is not intended or written to be used, and it cannot be used by the
recipient or any other taxpayer, for the purpose of avoiding Federal tax
penalties, and was not written to support the promotion or marketing of any
transaction or matter discussed herein.
--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
