Re: Parallel Apply

On Mon, Aug 11, 2025 at 10:15:41AM +0530, Amit Kapila wrote:
> Hi,
> 
> Background and Motivation
> -------------------------------------
> In high-throughput systems, where hundreds of sessions generate data
> on the publisher, the subscriber's apply process often becomes a
> bottleneck due to the single apply worker model. While users can
> mitigate this by creating multiple publication-subscription pairs,
> this approach has scalability and usability limitations.
> 
> Currently, PostgreSQL supports parallel apply only for large streaming
> transactions (streaming=parallel). This proposal aims to extend
> parallelism to non-streaming transactions, thereby improving
> replication performance in workloads dominated by smaller, frequent
> transactions.

I thought the approach for improving WAL apply speed, for both binary
and logical, was pipelining:

    https://en.wikipedia.org/wiki/Instruction_pipelining

rather than trying to do all the steps in parallel.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Do not let urgent matters crowd out time for investment in the future.