Re: [HACKERS] path toward faster partition pruning

From: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
To: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
Cc: Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Amit Langote <amitlangote09(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] path toward faster partition pruning
Date: 2018-04-04 13:29:56
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On 4 April 2018 at 19:04, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> On 2018/04/04 14:42, Amit Langote wrote:
>> Attached v48.
> I had forgotten to remove the static_pruning parameter I had added in the
> v47, because it is no longer used. Static pruning now occurs even if a
> step contains all Params, in which case each of
> get_matching_hash/list/range_bounds() functions returns offsets of all
> non-null datums, because the Params cannot be resolved to actual values
> during static pruning.

Thanks for updating. I've made a pass over v49 and I didn't find very
much wrong with it.

The only real bug I found was a missing IsA(rinfo->clause, Const) in
the pseudoconstant check inside

Most of the changes are comment fixes with a few stylistic changes
thrown which are pretty much all there just to try to shrink the code
a line or two or reduce indentation.

I feel pretty familiar with this code now and assuming the attached is
included I'm happy for someone else, hopefully, a committer to take a
look at it.

I'll leave the following notes:

1. Still not sure about RelOptInfo->has_default_part. This flag is
only looked at in generate_partition_pruning_steps. The RelOptInfo and
the boundinfo is available to look at, it's just that the
partition_bound_has_default macro is defined in partition.c rather
than partition.h.

2. Don't really like the new isopne variable name. It's not very
simple to decode, perhaps something like is_not_eq is better?

3. The part of the code I'm least familiar with is
get_steps_using_prefix_recurse(). I admit to not having had time to
fully understand that and consider ways to break it.

Marking as ready for committer.

David Rowley
PostgreSQL Development, 24x7 Support, Training & Services

Attachment Content-Type Size
v49_fixes_drowley.patch application/octet-stream 26.4 KB

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