Re: Control your disk usage in PG: Introduction to Disk Quota Extension

On Wed, Nov 21, 2018 at 09:47:44AM -0500, Robert Haas wrote:
> +1 for adding some hooks to support this kind of thing, but I think
> the names you've chosen are not very good. The hook name should
> describe the place from which it is called, not the purpose for which
> one imagines that it will be used, because somebody else might imagine
> another use. Both BufferExtendCheckPerms_hook_type and
> SmgrStat_hook_type are imagining that they know what the hook does -
> CheckPerms in the first case and Stat in the second case.

I personally don't mind making Postgres more pluggable, but I don't
think that we actually need the extra ones proposed here at the layer
of smgr, as smgr is already a layer designed to call an underlying set
of APIs able to extend, unlink, etc. depending on the storage type.

> For this particular purpose, I don't immediately see why you need a
> hook in both places. If ReadBuffer is called with P_NEW, aren't we
> guaranteed to end up in smgrextend()?

Yes, that's a bit awkward.
--
Michael