Horton

Re: Yet another fast GiST build

Heikki Linnakangas <hlinnaka@iki.fi>

View thread View on postgr.es
From: Heikki Linnakangas <hlinnaka@iki.fi>
To: Peter Geoghegan <pg@bowt.ie>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andrey Borodin <x4mmm@yandex-team.ru>, Justin Pryzby <pryzby@telsasoft.com>, Darafei Komяpa Praliaskouski <me@komzpa.net>, Pavel Borisov <pashkin.elfe@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Michael Paquier <michael@paquier.xyz>, Alexander Korotkov <a.korotkov@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2021-01-17T22:52:12Z
Lists: pgsql-hackers 
On 18/01/2021 00:35, Peter Geoghegan wrote:
> On Sun, Jan 17, 2021 at 12:50 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I noticed that gist_page_items() thinks it can hold inter_call_data->rel
>> open across a series of calls.  That's completely unsafe: the executor
>> might not run the call series to completion (see LIMIT), resulting in
>> relcache leak complaints.

Fixed, thanks! I changed it to return a tuplestore.

> It also has the potential to run into big problems should the user
> input a raw page image with an regclass-argument-incompatible tuple
> descriptor. Maybe that's okay (this is a tool for experts), but it
> certainly is a consideration.

I'm not sure I understand. It's true that the raw page image can contain 
data from a different index, or any garbage really. And the function 
will behave badly if you do that. That's an accepted risk with 
pageinspect functions, that's why they're superuser-only, although some 
of them are more tolerant of corrupt pages than others. The 
gist_page_items_bytea() variant doesn't try to parse the key data and is 
less likely to crash on bad input.

- Heikki

Commits

  1. Add sortsupport for gist_btree opclasses, for faster index builds.

  2. pageinspect: Fix relcache leak in gist_page_items().

  3. Fix test failure with wal_level=minimal.

  4. Enhance nbtree index tuple deletion.

  5. Fix portability issues in the new gist pageinspect test.

  6. Add functions to 'pageinspect' to inspect GiST indexes.

  7. Fix missing validation for the new GiST sortsupport functions.

  8. Fix compilation warning in xlog.c

  9. Set right-links during sorted GiST index build.

  10. Fix checksum calculation in the new sorting GiST build.

  11. Add support for building GiST index by sorting.