On 2018-Jun-14, Andres Freund wrote: > But I do think there's a few things that are doable without actually > needing to invoke any user defined code aside of the AM code > itself. E.g. heap pruning / aggressively setting hint bits doesn't need > to invoke operators, and I can think of some ways to implement index > delete marking that does so without invoking any comparators either.
So what you want to do is have bgwriter/checkpointer able to scan some catalog and grab a function pointer that can "execute pruning on this shared buffer", right? For that maybe we need to split out a part of AMs that is storage-level and another one that is data-level. So an access method would create two catalog entries, one of which is shared (pg_shared_am? ugh) and the other is the regular one we already have in pg_am. The handler function in pg_shared_am gives you functions that can only do storage-level stuff such as hint bit setting, page pruning, tuple freezing, CRC, etc which does not require access to the data itself. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services