Re: Add pg_buffercache_mark_dirty[_all] functions to the pg_buffercache

> It is a slightly disappointing that the loops for
> the buffers are duplicated, particularly for the relation vs the all
> case.

Yes, and we got another two loops in pg_buffercache_evict functions,
and more loops in Drop/Flush relation/database buffers functions. Maybe
we can abstract them into a generic loop function and it takes a buffer
handler function pointer to avoid duplication?

> One thing that would make more sense to me is to
> split the patch in two: one for the changes in bufmgr.c/h and one for
> pg_buffercache.  There can be an argument that these new APIs could be
> useful for out-of-core code, as well, to let developers play with the
> state of the buffers.  I mean, why not, the thread is also about API
> extensibility, as well, to enforce dirty states.  :)

Agreed. It might be three, one for generic loop function, one for API
and one for pg_buffercache. If we put new API out-of-core, the latter
two can be merged.

Best regards,
Yuhang Qiu