Horton

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

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2019-07-05T18:52:27Z
Lists: pgsql-hackers 
On Thu, Jul  4, 2019 at 05:06:09PM -0700, Peter Geoghegan wrote:
> This result is very impressive. We'll need to revisit what the right
> trade-off is for the compression scheme, which Heikki had some
> thoughts on when we left off 3 years ago, but that should be a lot
> easier now. I am very encouraged by the fact that this relatively
> simple approach already works quite nicely. It's also great to see
> that bulk insertions with lots of compression are very clearly faster
> with this latest revision of your patch, unlike earlier versions from
> 2016 that made those cases slower (though I haven't tested indexes
> that don't really use compression). I think that this is because you
> now do the compression lazily, at the point where it looks like we may
> need to split the page. Previous versions of the patch had to perform
> compression eagerly, just like GIN, which is not really appropriate
> for nbtree.

I am also encouraged and am happy we can finally move this duplicate
optimization forward.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

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.