On Mon, Mar 11, 2024 at 4:09 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > I don't see how it will be easier for the user to choose the default > value of 'max_slot_xid_age' compared to 'max_slot_wal_keep_size'. But, > I agree similar to 'max_slot_wal_keep_size', 'max_slot_xid_age' can be > another parameter to allow vacuum to proceed removing the rows which > otherwise it wouldn't have been as those would be required by some > slot. Now, if this understanding is correct, we should probably make > this invalidation happen by (auto)vacuum after computing the age based > on this new parameter.
Currently, the patch computes the XID age in the checkpointer using the next XID (gets from ReadNextFullTransactionId()) and slot's xmin and catalog_xmin. I think the checkpointer is best because it already invalidates slots for wal_removed cause, and flushes all replication slots to disk. Moving this new invalidation functionality into some other background process such as autovacuum will not only burden that process' work but also mix up the unique functionality of that background process. Having said above, I'm open to ideas from others as I'm not so sure if there's any issue with checkpointer invalidating the slots for new reasons. -- Bharath Rupireddy PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
