Hi, Commit 91f2cae7a4e that introduced WALReadFromBuffers only used it for physical walsenders. It can also be used in more places benefitting logical walsenders, backends running pg_walinspect and logical decoding functions if the WAL is available in WAL buffers. I'm attaching a 0001 patch for this.
While at it, I've also added a test module in 0002 patch to demonstrate 2 things: 1) how the caller can ensure the requested WAL is fully copied to WAL buffers using WaitXLogInsertionsToFinish before reading from WAL buffers. 2) how one can implement an xlogreader page_read callback to read unflushed/not-yet-flushed WAL directly from WAL buffers. FWIW, a separate test module to explicitly test the new function is suggested here - https://www.postgresql.org/message-id/CAFiTN-sE7CJn-ZFj%2B-0Wv6TNytv_fp4n%2BeCszspxJ3mt77t5ig%40mail.gmail.com. Please have a look at the attached patches. I will register this for the next commit fest. -- Bharath Rupireddy PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
v1-0001-Use-WALReadFromBuffers-in-more-places.patch
Description: Binary data
v1-0002-Add-test-module-to-demonstrate-reading-from-WAL-b.patch
Description: Binary data
