Re: removal of dangling temp tables

On 2018-Dec-26, Tsunakawa, Takayuki wrote:

> From: Alvaro Herrera [mailto:alvherre@2ndquadrant.com]
> > The more aggressive action is to backpatch 943576bddcb5 ("Make autovacuum
> > more aggressive to remove orphaned temp tables") which is currently only
> > in pg11.  We would put the new PGPROC member at the end of the struct, to
> > avoid ABI incompatibilities, but it'd bring trouble for extensions that
> > put PGPROC in arrays.  I checked the code of some known extensions; found
> > that pglogical uses PGPROC, but only pointers to it, so it wouldn't be
> > damaged by the proposed change AFAICS.
> 
> +1
> I think this is a bug from a user's perspective that garbage is left.
> I want to believe that fixing bugs of PostgreSQL itself are
> prioritized over the ABI compatibility for extensions, if we have to
> choose one of them.

Having been victim of ABI incompatibility myself, I loathe giving too
much priority to other issues that can be resolved in other ways, so I
don't necessarily support your view on bugs.
That said, I think in this case it shouldn't be a problem, so I'm going
to work on that next.

I haven't got around to creating the abidiff reporting system yet ...

> > Another possibly useful change is to make DISCARD ALL and DISCARD TEMP delete
> > everything in what would be the backend's temp namespace, even if it hasn't
> > been initialized yet.  This would cover the case where a connection pooler
> > keeps the connection open for a very long time, which I think is a common
> > case.
> 
> That sounds good.

Thanks.  I just tested that the attached patch does the intended.  (I
named it "autovac" but obviously the DISCARD part is not about
autovacuum).  I intend to push this patch first, and later backpatch the
other one.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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