Re: BTScanOpaqueData size slows down tests - Mailing list pgsql-hackers

From Andres Freund
Subject Re: BTScanOpaqueData size slows down tests
Date
Msg-id bulfwzsrb4wfor7lm3s2cvelzip2c5o7vyzz5ysjcpgva6cdmp@vvazliwl5uaj
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In response to Re: BTScanOpaqueData size slows down tests  (David Rowley <dgrowleyml@gmail.com>)
List pgsql-hackers
Hi,

On 2025-04-03 11:26:08 +1300, David Rowley wrote:
> On Thu, 3 Apr 2025 at 04:21, Andres Freund <andres@anarazel.de> wrote:
> > I was mildly
> > surprised to see how expensive the new compact attribute checks are.
> 
> Is this a fairly deform-heavy workload?

It was our regression tests, although I was playing around with combining
various groups in the schedule to get the tests to pass faster overall (on
average we just use 2.8 cores, which seems depressingly low).

I do see a about a 6-7% increase in test time with just the default schedule.


> I feel having something to check these are in sync is worthwhile. It did
> find bugs during the development of the patch.

I agree. But I wonder if we couldn't make it a bit smarter than right
now. Afaict we'll recheck it over and over, which does seem a bit extreme.

When running queries that deform a lot, the overhead is rather substantial.

With pgbench of f <(echo 'SELECT sum(pronargs) FROM pg_proc;') I see 2155 TPS
with the call to verify_compact_attribute() commented out and 827 TPS without.

Greetings,

Andres Freund



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