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Re: non-overlapping, consecutive partitions

From: Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Boszormenyi Zoltan <zb(at)cybertec(dot)at>
Subject: Re: non-overlapping, consecutive partitions
Date: 2010-07-29 15:12:09
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
hello ...

yeah, this is fairly complicated.

can you send me how far you got?
i would be curious to see how you have attacked this issue.

i am still in the process of checking the codes.
we somehow have to find a solution for that. otherwise we are in slight trouble here.
it seems we have to solve it no matter what it takes.

	many thanks,


On Jul 26, 2010, at 1:14 AM, Robert Haas wrote:

> On Sun, Jul 25, 2010 at 6:40 PM, Greg Stark <gsstark(at)mit(dot)edu> wrote:
>> 2010/7/25 Robert Haas <robertmhaas(at)gmail(dot)com>:
>>> 2010/7/25 PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>:
>>>> On Jul 25, 2010, at 11:56 AM, Martijn van Oosterhout wrote:
>>>>> I think the right way to approach this is to teach the planner about
>>>>> merge sorts.
>> For what it's worth I think this is a belt-and-suspenders type of
>> situation where we want two solutions which overlap somewhat.
>> I would really like to have merge-append nodes because there are all
>> sorts of plans where append nodes destroying the ordering of their
>> inputs eliminates a lot of good plans. Those cases can be UNION ALL
>> nodes, or partitions where there's no filter on the partition key at
>> all.
>> But for partitioned tables like the OPs the "real" solution would be
>> to have more structured meta-data about the partitions that allows the
>> planner to avoid needing the merge at all. It would also means the
>> planner wouldn't need to look at every node; it could do a binary
>> search or equivalent for the right partitions.
> Agreed on all points.
>>> Greg Stark had a patch to do this a while back called merge append,
>>> but it never got finished...
>> I was basically in over my head with the planner. I don't understand
>> how equivalent classes are used or should be used and didn't
>> understand the code I was pointed at as being analogous. It's probably
>> not so complicated as all that, but I never really wrapped my head
>> around it and moved onto tasks I could make more progress on.
> Yeah, I don't fully understand those either.
> -- 
> Robert Haas
> EnterpriseDB:
> The Enterprise Postgres Company
> -- 
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