Horton

Re: [HACKERS] [WIP] Effective storage of duplicates in B-tree index.

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Cc: Rafia Sabih <rafia.pghackers@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2019-07-20T02:24:48Z
Lists: pgsql-hackers

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On Fri, Jul 19, 2019 at 12:32 PM Peter Geoghegan <pg@bowt.ie> wrote:
> On Fri, Jul 19, 2019 at 10:53 AM Anastasia Lubennikova
> <a.lubennikova@postgrespro.ru> wrote:
> > Patch 0002 (must be applied on top of 0001) implements preserving of
> > correct TID order
> > inside posting list when inserting new tuples.
> > This version passes all regression tests including amcheck test.
> > I also used following script to test insertion into the posting list:
>
> Nice!

Hmm. So, the attached test case fails amcheck verification for me with
the latest version of the patch:

$ psql -f amcheck-compress-test.sql
DROP TABLE
CREATE TABLE
CREATE INDEX
CREATE EXTENSION
INSERT 0 2001
psql:amcheck-compress-test.sql:6: ERROR:  down-link lower bound
invariant violated for index "idx_desc_nl"
DETAIL:  Parent block=3 child index tid=(2,2) parent page lsn=10/F87A3438.

Note that this test only has an INSERT statement. You have to use
bt_index_parent_check() to see the problem -- bt_index_check() will
not detect the problem.

-- 
Peter Geoghegan

Commits

  1. Teach pageinspect about nbtree deduplication.

  2. Doc: Fix deduplicate_items index term.

  3. Revise BTP_HAS_GARBAGE nbtree VACUUM comments.

  4. Remove unneeded "pin scan" nbtree VACUUM code.

  5. Cleanup code in reloptions.h regarding reloption handling

  6. Catch invalid typlens in a couple of places

  7. Compute XID horizon for page level index vacuum on primary.

  8. Make heap TID a tiebreaker nbtree index column.

  9. Avoid pin scan for replay of XLOG_BTREE_VACUUM in all cases

  10. Revert buggy optimization of index scans

  11. Restructure index access method API to hide most of it at the C level.

  12. Reduce pinning and buffer content locking for btree scans.

  13. Avoid scanning nulls at the beginning of a btree index scan.