Horton

Re: WIP: Covering + unique indexes.

Anastasia Lubennikova <a.lubennikova@postgrespro.ru>

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From: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
To: Peter Geoghegan <pg@heroku.com>
Cc: David Steele <david@pgmasters.net>, Michael Paquier <michael.paquier@gmail.com>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>, David Rowley <david.rowley@2ndquadrant.com>
Date: 2016-04-07T16:01:42Z
Lists: pgsql-hackers

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06.04.2016 23:52, Peter Geoghegan:
> On Wed, Apr 6, 2016 at 1:50 PM, Peter Geoghegan <pg@heroku.com> wrote:
>> Personally, I like documenting assertions, and will sometimes write
>> assertions that the compiler could easily optimize away. Maybe going
>> *that* far is more a matter of personal style, but I think an
>> assertion about the new index tuple size being <= the old one is just
>> a good idea. It's not about a problem in your code at all.
> You should make index_truncate_tuple()/index_reform_tuple() promise to
> always do this in its comments/contract with caller as part of this,
> IMV.
>

Mentioned issues are fixed. Patch is attached.

I'd like to remind you that the commitfest will be closed very-very 
soon, so I'd like to get your final resolution about the patch.
Not to have it in the 9.6 release will be very disappointing.

I agree that b-tree is a crucial subsystem. But it seems to me, that we 
have lack of improvements in this area
not only because of the algorithm's complexity but also because of lack 
of enthusiasts to work on it and struggle through endless discussions.
But it's off-topic here. Attention to these development difficulties 
will be one of the messages of my pgcon talk.

You know, we lost a lot of time discussing various b-tree problems.
Besides that, I am sure that the patch is really in a good shape. It 
hasn't any open problems to fix.
And possible subtle bugs can be found at the testing stage of the release.

Looking forward to your reply.

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

Commits

  1. Adjust INCLUDE index truncation comments and code.

  2. Add commentary explaining why MaxIndexTuplesPerPage calculation is safe.

  3. Indexes with INCLUDE columns and their support in B-tree

  4. Add amcheck verification of heap relations belonging to btree indexes.

  5. Doc: move info for btree opclass implementors into main documentation.

  6. Doc: mention that you can't PREPARE TRANSACTION after NOTIFY.

  7. Remove dedicated B-tree root-split record types.

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

  9. Split _bt_insertonpg to two functions.

  10. Major overhaul of btree index code. Eliminate special BTP_CHAIN logic for