Horton

Re: [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: David Steele <david@pgmasters.net>, pgsql-hackers@postgresql.org
Date: 2016-03-18T17:19:37Z
Lists: pgsql-hackers

Attachments

Please, find the new version of the patch attached. Now it has WAL 
functionality.

Detailed description of the feature you can find in README draft 
https://goo.gl/50O8Q0

This patch is pretty complicated, so I ask everyone, who interested in 
this feature,
to help with reviewing and testing it. I will be grateful for any feedback.
But please, don't complain about code style, it is still work in progress.

Next things I'm going to do:
1. More debugging and testing. I'm going to attach in next message 
couple of sql scripts for testing.
2. Fix NULLs processing
3. Add a flag into pg_index, that allows to enable/disable compression 
for each particular index.
4. Recheck locking considerations. I tried to write code as less 
invasive as possible, but we need to make sure that algorithm is still 
correct.
5. Change BTMaxItemSize
6. Bring back microvacuum functionality.

-- 
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.