Feedback-ID: i0fe9450f:Fastmail
Date: Wed, 11 Mar 2026 08:29:51 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Andres Freund <andres@anarazel.de>
Cc: Xuneng Zhou <xunengzhou@gmail.com>,
	pgsql-hackers <pgsql-hackers@lists.postgresql.org>,
	Nazir Bilal Yavuz <byavuz81@gmail.com>
Subject: Re: Streamify more code paths
Message-ID: <abCpb4VBwmzn9s_P@paquier.xyz>
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On Tue, Mar 10, 2026 at 07:04:37PM -0400, Andres Freund wrote:
> It might be a good idea to run the benchmarks with debug_io_direct=data.
> That'll make them very slow, since the write side doesn't yet use AIO and thus
> will do a lot of synchronous writes, but it should still allow to evaluate the
> gains from using read stream.

Ah, thanks for the tip.  I'll go try that.

> The other thing that's kinda important to evaluate read streams is to test on
> higher latency storage, even without direct IO.  Many workloads are not at all
> benefiting from AIO when run on a local NVMe SSD with < 10us latency, but are
> severely IO bound when run on a cloud storage disk with 0.5ms - 4ms latency.

My previous run was on a cloud instance, I don't have access to a SSD
with this amount of latency locally.

One thing that was standing on is the bloom bitmap case that was
looking really nice for a large number of rows, so I have applied
this part.  The rest is going to need a bit more testing to build more
confidence, as far as I can see.
--
Michael

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