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: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2019-12-20T02:55:52Z

Lists: pgsql-hackers

Attachments

v27-0002-Teach-pageinspect-about-nbtree-posting-lists.patch (application/octet-stream) patch v27-0002
v27-0003-DEBUG-Show-index-values-in-pageinspect.patch (application/octet-stream) patch v27-0003
v27-0001-Add-deduplication-to-nbtree.patch (application/octet-stream) patch v27-0001

On Tue, Dec 17, 2019 at 7:27 PM Peter Geoghegan <pg@bowt.ie> wrote:
> I plan to commit this first patch [1] in the next day or two, barring
> any objections.

I pushed this earlier today -- it became commit 9f83468b. Attached is
v27, which fixes the bitrot against the master branch.

Other changes:

* Updated _bt_form_posting() to consistently MAXALIGN(). No behavioral
changes here. The defensive SHORTALIGN()s we had in v26 should have
been defensive MAXALIGN()s -- this has been fixed.  Also, we now also
explain our precise assumptions around alignment.

* Cleared up the situation around _bt_dedup_one_page()'s
responsibilities as far as LP_DEAD items go.

* Fixed bug in 32 KiB BLCKSZ builds. We now apply an additional
INDEX_SIZE_MASK cap on posting list tuple size.

-- 
Peter Geoghegan

Commits

Teach pageinspect about nbtree deduplication.
- 93ee38eade1b 13.0 landed
Doc: Fix deduplicate_items index term.
- e537aed61db7 13.0 landed
Revise BTP_HAS_GARBAGE nbtree VACUUM comments.
- 4b25f5d0ba01 13.0 cited
Remove unneeded "pin scan" nbtree VACUUM code.
- 9f83468b3536 13.0 landed
Cleanup code in reloptions.h regarding reloption handling
- 50d22de9325f 13.0 cited
Catch invalid typlens in a couple of places
- 8557a6f10ca6 13.0 cited
Compute XID horizon for page level index vacuum on primary.
- 558a9165e081 12.0 cited
Make heap TID a tiebreaker nbtree index column.
- dd299df8189b 12.0 cited
Avoid pin scan for replay of XLOG_BTREE_VACUUM in all cases
- 3e4b7d87988f 9.6.0 cited
Revert buggy optimization of index scans
- c7111d11b188 9.6.0 cited
Restructure index access method API to hide most of it at the C level.
- 65c5fcd353a8 9.6.0 cited
Reduce pinning and buffer content locking for btree scans.
- 2ed5b87f96d4 9.5.0 cited
Avoid scanning nulls at the beginning of a btree index scan.
- 1a77f8b63d15 9.2.0 cited