Horton

Re: Some read stream improvements

Kirill Reshke <reshkekirill@gmail.com>

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From: Kirill Reshke <reshkekirill@gmail.com>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, Andres Freund <andres@anarazel.de>
Date: 2025-02-17T05:55:26Z
Lists: pgsql-hackers 
On Mon, 17 Feb 2025 at 09:55, Thomas Munro <thomas.munro@gmail.com> wrote:
>
> Hi,
>
> Here are some patches that address some of Andres's feedback since the
> AIO v2 rebase[1], anticipate out-of-order streams, and make some other
> minor improvements.  They are independent of the main AIO patch set
> and apply to master, hence separate thread.

Hi, great!

> 0001-Refactor-read_stream.c-s-circular-arithmetic.patch
>
> This just replaced open-coded arithmetic with inline functions.  They
> will be used a lot more in later work, and provide central places to
> put assertions that were not checked as uniformly as I would like.

Just out of curiosity, should we `Assert(*index + n <
stream->queue_size);` in `read_stream_index_advance_n`?


-- 
Best regards,
Kirill Reshke

Commits

  1. read_stream: Fix overflow hazard with large shared buffers

  2. Support buffer forwarding in StartReadBuffers().

  3. Support buffer forwarding in read_stream.c.

  4. Simplify distance heuristics in read_stream.c.

  5. Improve read_stream.c advice for dense streams.

  6. Respect changing pin limits in read_stream.c.

  7. Improve buffer manager API for backend pin limits.

  8. Remove arbitrary cap on read_stream.c buffer queue.