Re: Change GUC hashtable to use simplehash? - Mailing list pgsql-hackers

From John Naylor
Subject Re: Change GUC hashtable to use simplehash?
Date
Msg-id CANWCAZbPOtvqqR7wNFefRD+cwOVDhUFbhq70A6YDGi+hGV6RXg@mail.gmail.com
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In response to Re: Change GUC hashtable to use simplehash?  (Ants Aasma <ants.aasma@cybertec.at>)
List pgsql-hackers
On Tue, Jan 30, 2024 at 7:51 PM Ants Aasma <ants.aasma@cybertec.at> wrote:
>
> It didn't calculate the same result because the if (mask) condition
> was incorrect. Changed it to if (chunk & 0xFF) and removed the right
> shift from the mask.

Yes, you're quite right.

> It seems to be half a nanosecond faster, but as I
> don't have a machine set up for microbenchmarking it's quite close to
> measurement noise.

With my "throughput-ush" test, they look good:

pgbench -n -T 20 -f bench_cstr_aligned.sql -M prepared | grep latency

master:
latency average = 490.722 ms

(Ants Aantsma) v-17 0001:
latency average = 385.263 ms

v17 0001+0002:
latency average = 339.506 ms

> I didn't post the harness as it's currently so messy to be near
> useless to others. But if you'd like to play around,  I can tidy it up
> a bit and post it.

I'd be curious, thanks.

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