Re: Name for new VACUUM - Mailing list pgsql-hackers

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> Not necessarily.  Concurrent VACUUM does truncate the relation if it can
> >> do so conveniently --- for example, it will successfully reclaim space
> >> if you do "DELETE FROM foo; VACUUM foo;".  It just doesn't try as hard
> >> as the older VACUUM code does.
> 
> > But it will not reclaim from UPDATE.
> 
> What?  I have no idea what you mean by that.

I meant that UPDATE of all rows in a table put the new rows at the end.

> >  You also will have to VACUUM
> > NOLOCK right after your delete or the next INSERT is going to go on the
> > end and VACUUM NOLOCK is not going to compact the table, right?
> 
> INSERTs don't go on the end in the first place, at least not under
> steady-state conditions.  That's what the free space map is all about.

But you are assuming you have stuff in the free space map for the table
already, right?  I as not assuming that.

> > My contention is that we are causing more problems for administrators by
> > changeing VACUUM's default behavior.
> 
> This is a curious definition of causing problems: making it work better
> is causing a problem?  I didn't think we'd elevated backwards
> compatibility to quite that much of a holy grail.  To me, a backwards
> compatibility problem is something that actually breaks an existing app.
> I do not see how changing vacuum's default behavior will break anything.

It will not break.  It is just you were saying making VACUUM NOLOCK the
default is less work for administrators because they don't have to
update their scripts.  I am saying that there is more updating required
for making NOLOCK the default.  However, maybe more typing if they do
NOLOCk more frequently.

> >> Right now it's called VACUUM FULL, but I'm not particularly wedded to
> >> that name.  Does anyone else like VACUUM LOCK?  Or have an even better
> >> idea?
> 
> > FULL seems overloaded to me.  Maybe LOCK or FORCE.
> 
> LOCK is pretty overloaded too, but I don't have any other objection to
> it.  "FORCE" is meaningless; what are you forcing, and just how much
> force are you applying?

No idea.  ANALYZE isn't the greatest word either, but it was mine.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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