Re: speeding up planning with partitions

From: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
To: "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com>
Cc: "'David Rowley'" <david(dot)rowley(at)2ndquadrant(dot)com>, "'Alvaro Herrera'" <alvherre(at)2ndquadrant(dot)com>, "'Pg Hackers'" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: speeding up planning with partitions
Date: 2018-12-27 11:25:38
Message-ID: 55bd88c6-f311-2791-0a36-11c693c69753@lab.ntt.co.jp
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Hi,

On 2018/12/26 13:28, Amit Langote wrote:
> On 2018/12/25 16:47, Imai, Yoshikazu wrote:
>> adjust_inherit_target_child() is in allpaths.c in your patch, but it has the
>> code like below ones which are in master's(not patch applied) planner.c or
>> planmain.c, so could it be possible in planner.c(or planmain.c)?
>> This point is less important, but I was just wondering whether
>> adjust_inherit_target_child() should be in allpaths.c, planner.c or planmain.c.
>>
>> + /* Translate the original query's expressions to this child. */
>> + subroot = makeNode(PlannerInfo);
>> + memcpy(subroot, root, sizeof(PlannerInfo));
>>
>> + root->parse->targetList = root->unexpanded_tlist;
>> + subroot->parse = (Query *) adjust_appendrel_attrs(root,
>> + (Node *) root->parse,
>> + 1, &appinfo);
>>
>> + tlist = preprocess_targetlist(subroot);
>> + subroot->processed_tlist = tlist;
>> + build_base_rel_tlists(subroot, tlist);
>
> I'm thinking of changing where adjust_inherit_target_child gets called
> from. In the current patch, it's in the middle of set_rel_size which I'm
> starting to think is a not a good place for it. Maybe, I'll place the
> call call near to where inheritance is expanded.

So what I did here is that I added a new step to query_planner() itself
that adds the PlannerInfos for inheritance child target relations and
hence moved the function adjust_inherit_target_child() to planmain.c and
renamed it to add_inherit_target_child_root(). I've removed its
RelOptInfo argument and decided to modify the child RelOptInfo's
targetlist in allpaths.c. So, add_inherit_target_child_root() only builds
the child PlannerInfo now. Child PlannerInfo's are now stored in an array
of simple_rel_array_size elements, instead of a list. It's filled with
NULLs except for the slots corresponding to child target relations.

In allpaths.c, I've added set_inherit_target_rel_sizes and
set_inherit_target_rel_pathlists, which look like set_append_rel_size and
set_append_rel_pathlist, respectively. The reason to add separate
functions for the target relation case is that we don't want to combine
the outputs of children to form an "append relation" in that case. So,
this patch no longer modifies set_append_rel_size for handling the case
where the parent relation is query's target relation.

> I will send an updated patch hopefully before my new year vacation that
> starts on Friday this week.

Here's the v10 of the patch. I didn't get chance to do more changes than
those described above and address Imai-san's review comments yesterday.

Have a wonderful new year! I'll be back on January 7 to reply on this thread.

Thanks,
Amit

Attachment Content-Type Size
v10-0001-Overhaul-inheritance-update-delete-planning.patch text/plain 71.2 KB
v10-0002-Store-inheritance-root-parent-index-in-otherrel-.patch text/plain 2.5 KB
v10-0003-Lazy-creation-of-RTEs-for-inheritance-children.patch text/plain 91.5 KB
v10-0004-Move-append-expansion-code-into-its-own-file.patch text/plain 112.7 KB
v10-0005-Teach-planner-to-only-process-unpruned-partition.patch text/plain 6.9 KB
v10-0006-Do-not-lock-all-partitions-at-the-beginning.patch text/plain 1.8 KB

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