Re: Improve WALRead() to suck data directly from WAL buffers when possible

On Thu, Mar 21, 2024 at 11:33 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> Please find the v26 patches after rebasing.

Commit f3ff7bf83b added a check in WALReadFromBuffers to ensure the
requested WAL is not past the WAL that's copied to WAL buffers. So,
I've dropped v26-0001 patch.

I've attached v27 patches for further review.

0001 adds a test module to demonstrate reading from WAL buffers
patterns like the caller ensuring the requested WAL is fully copied to
WAL buffers using WaitXLogInsertionsToFinish and an implementation of
xlogreader page_read
callback to read unflushed/not-yet-flushed WAL directly from WAL buffers.

0002 Use WALReadFromBuffers in more places like for logical
walsenders, logical decoding functions, backends reading WAL.

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com