Date: Wed, 3 Dec 2014 08:01:38 -0600
From: "ktm@rice.edu" <ktm@rice.edu>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>,
 "'Robert Haas'" <robertmhaas@gmail.com>,
 "'Andres Freund'" <andres@2ndquadrant.com>,
 "'Bruce Momjian'" <bruce@momjian.us>,
 "'Pg Hackers'" <pgsql-hackers@postgresql.org>
Subject: Re: On partitioning
Message-ID: <20141203140138.GG10679@aart.rice.edu>
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On Wed, Dec 03, 2014 at 10:00:26AM -0300, Alvaro Herrera wrote:
> Amit Langote wrote:
> 
> > From: Robert Haas [mailto:robertmhaas@gmail.com]
> 
> > > What is an overflow partition and why do we want that?
> > 
> > That would be a default partition. That is, where the tuples that
> > don't belong elsewhere (other defined partitions) go. VALUES clause of
> > the definition for such a partition would look like:
> > 
> > (a range partition) ... VALUES LESS THAN MAXVALUE 
> > (a list partition) ... VALUES DEFAULT
> > 
> > There has been discussion about whether there shouldn't be such a
> > place for tuples to go. That is, it should generate an error if a
> > tuple can't go anywhere (or support auto-creating a new one like in
> > interval partitioning?)
> 
> In my design I initially had overflow partitions too, because I
> inherited the idea from Itagaki Takahiro's patch.  Eventually I realized
> that it's a useless concept, because you can always have leftmost and
> rightmost partitions, which are just regular partitions (except they
> don't have a "low key", resp. "high key").  If you don't define
> unbounded partitions at either side, it's fine, you just raise an error
> whenever the user tries to insert a value for which there is no
> partition.
> 
Hi,

Maybe I am not clear on the concept of an overflow partition, but I
thought that it functioned to catch any record that did not fit the
partitioning scheme. You end of range with out a "low key" or "high
key" would only catch problems in those areas. If you partitioned on
work days of the week, you should not have anything on Saturday/Sunday.
How would that work? You would want to catch anything that was not a
weekday in the overflow.

Regards,
Ken


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