Horton

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

Anastasia Lubennikova <a.lubennikova@postgrespro.ru>

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From: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
To: Peter Geoghegan <pg@bowt.ie>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-08-21T17:19:38Z
Lists: pgsql-hackers

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20.08.2019 4:04, Peter Geoghegan wrote:
> On Fri, Aug 16, 2019 at 8:56 AM Anastasia Lubennikova
> <a.lubennikova@postgrespro.ru> wrote:
>
>> It seems that now all replace operations are crash-safe. The new patch passes
>> all regression tests, so I think it's ready for review again.
> I'm looking at it now. I'm going to spend a significant amount of time
> on this tomorrow.
>
> I think that we should start to think about efficient WAL-logging now.

Thank you for the review.

The new version v8 is attached. Compared to previous version, this patch 
includes
updated btree_xlog_insert() and btree_xlog_split() so that WAL records 
now only contain data
about updated posting tuple and don't require full page writes.
I haven't updated pg_waldump yet. It is postponed until we agree on 
nbtxlog changes.

Also in this patch I renamed all 'compress' keywords to 'deduplicate' 
and did minor cleanup
of outdated comments.

I'm going to look through the patch once more to update nbtxlog 
comments, where needed and
answer to your remarks that are still left in the comments.

-- 
Anastasia Lubennikova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

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.