Re: libpq: PQgetCopyData() and allocation overhead

Here's the patch (as a PR just to make it easy to read): https://github.com/jtv/postgres/pull/1

I don't have an easily readable benchmark yet, since I've been timing the potential impact on libpqxx.  But can do that next.

Jeroen

On Fri, Feb 10, 2023, 11:26 Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote:

On Fri, Feb 10, 2023 at 3:43 PM Jeroen Vermeulen <jtvjtv@gmail.com> wrote:
>
> Would there be interest in a variant of PQgetCopyData() that re-uses the same buffer for a new row, rather than allocating a new buffer on each iteration?
>
> I tried it on a toy benchmark, and it reduced client-side CPU time by about 12%.  (Less of a difference in wall-clock time of course; the client was only using the CPU for a bit over half the time.)

Interesting. It might improve logical replication performance too as
it uses COPY protocol.

Do you mind sharing a patch, test case that you used and steps to
verify the benefit?

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