pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: Tom Lane <tgl@sss.pgh.pa.us>
To: Daniel Gustafsson <daniel@yesql.se>
Cc: David Rowley <david.rowley@2ndquadrant.com>
Cc: Jesper Pedersen <jesper.pedersen@redhat.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: POC: converting Lists into arrays
Date: Wed, 17 Jul 2019 10:53:53 -0400
Message-ID: <19396.1563375233@sss.pgh.pa.us> (raw )
In-Reply-To: <3C77817B-959F-4D70-ABB1-97FFA478F1AE@yesql.se >
References: <481.1551390571@sss.pgh.pa.us >
<24783.1551568303@sss.pgh.pa.us >
<20190303043424.itzy3ge52xrkpmpr@alap3.anarazel.de >
<437.1551637744@sss.pgh.pa.us >
<CA+TgmoZM4c=v0ifR++i09JFtNtnqTq_HkFmbFjwWqbUJffOLmA@mail.gmail.com >
<12684.1551723095@sss.pgh.pa.us >
<20190304190612.vgqqsowzkrh22623@alap3.anarazel.de >
<26464.1551734920@sss.pgh.pa.us >
<20190304221101.hdg4vj5fo4eewh3b@alap3.anarazel.de >
<CAKJS1f-pNfoUJrmU8vgD1WrKLqs9WxOVLQ0RpSWu9h6W9RnypA@mail.gmail.com >
<20190304235402.nod3gbotk2qtd4nh@alap3.anarazel.de >
<CAKJS1f-yS201hAAmnxcLb2aeTYNZ_A9R1JNXF6hTVXjhHYN7rQ@mail.gmail.com >
<1131.1551746172@sss.pgh.pa.us >
<14626.1558745627@sss.pgh.pa.us >
<29297.1558799327@sss.pgh.pa.us >
<f078ce63-9e04-0f3e-d200-d7ee66279abe@redhat.com >
<25178.1562006685@sss.pgh.pa.us >
<25258.1562023641@sss.pgh.pa.us >
<CAKJS1f9RUaLrujzpqf15gg_7Wo9-ai7b3-MR=bMH7a-pOWdeZA@mail.gmail.com >
<2305.1562181615@sss.pgh.pa.us >
<21272.1563318411@sss.pgh.pa.us >
<3C77817B-959F-4D70-ABB1-97FFA478F1AE@yesql.se >
Daniel Gustafsson <daniel@yesql.se> writes:
> For cases where an Oid list is copied and then head elements immediately
> removed, as in fetch_search_path, couldn’t we instead use a counter and
> list_copy_tail to avoid repeated list_delete_first calls?
Perhaps, but I'm having a hard time getting excited about it.
I don't think there's any evidence that fetch_search_path is a
performance issue. Also, this coding requires that the *only*
changes be deletion of head elements, whereas as it stands,
once we've copied the list we can do what we like.
> Since we’ve allowed list_delete_first on NIL for a long time, it seems
> reasonable to do the same for list_delete_last even though it’s hard to come up
> with a good usecase for deleting the last element without inspecting the list
> (a stack growing from the bottom perhaps?
Yeah, I intentionally made the edge cases the same. There's room to argue
that both functions should error out on NIL, instead. I've not looked
into that though, and would consider it material for a separate patch.
> Looking mainly at 0001 for now, I agree that the order is insignificant.
Thanks for looking!
regards, tom lane
view thread (130+ messages) latest in thread
Message-ID: <19396.1563375233@sss.pgh.pa.us>
Permalink: ../19396.1563375233@sss.pgh.pa.us/
Also on: postgresql.org/message-id/19396.1563375233@sss.pgh.pa.us
copy link · copy postgr.es
reply Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, daniel@yesql.se, david.rowley@2ndquadrant.com, jesper.pedersen@redhat.com, andres@anarazel.de, robertmhaas@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: POC: converting Lists into arrays
In-Reply-To: <19396.1563375233@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox