RE: speeding up planning with partitions

From: "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com>
To: 'Amit Langote' <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
Cc: Imai Yoshikazu <yoshikazu_i443(at)live(dot)jp>, "jesper(dot)pedersen(at)redhat(dot)com" <jesper(dot)pedersen(at)redhat(dot)com>, 'Amit Langote' <amitlangote09(at)gmail(dot)com>, "David Rowley" <david(dot)rowley(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Alvaro Herrera" <alvherre(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: RE: speeding up planning with partitions
Date: 2019-03-26 10:02:55
Message-ID: 0F97FA9ABBDBE54F91744A9B37151A512B8CE5@g01jpexmbkw24
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On Tue, Mar 26, 2019 at 7:17 AM, Amit Langote wrote:
> Rebased patches attached.

I could only do the code review of v36-0001.

On Mon, Mar 25, 2019 at 11:35 AM, Amit Langote wrote:
> On 2019/03/23 6:07, Tom Lane wrote:
> > Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> writes:
> >> [ v34 patch set ]
> >
> > I had a bit of a look through this. I went ahead and pushed 0008 and
> > 0009, as they seem straightforward and independent of the rest. (BTW,
> > 0009 makes 0003's dubious optimization in set_relation_partition_info
> > quite unnecessary.) As for the rest:
> >
> > 0001: OK in principle, but I wonder why you implemented it by adding
> > another recursive scan of the jointree rather than just iterating
> > over the baserel array, as in make_one_rel() for instance. Seems
> > like this way is more work, and more code that we'll have to touch
> > if we ever change the jointree representation.
> I've changed this to work by iterating over baserel array. I was mostly
> worried about looping over potentially many elements of baserel array that
> we simply end up skipping, but considering the other patch that delays
> adding inheritance children, we don't need to worry about that.
> > I also feel like you used a dartboard while deciding where to insert the
> > call in query_planner(); dropping it into the middle of a sequence of
> > equivalence-class-related operations seems quite random. Maybe we could
> > delay that step all the way to just before make_one_rel, since the other
> > stuff in between seems to only care about baserels? For example,
> > it'd certainly be better if we could run remove_useless_joins before
> > otherrel expansion, so that we needn't do otherrel expansion at all
> > on a table that gets thrown away as being a useless join.
> create_lateral_join_info() expects otherrels to be present to propagate
> the information it creates.
> I have moved add_other_rels_to_query() followed by
> create_lateral_join_info() to just before make_one_rel().

I checked 0001 patch modifies the thing which is discussed above correctly.

What problem I only found is a little typo.

I'm really sorry for my shortage of time to review for now...

Yoshikazu Imai

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