Horton

Re: WIP: Covering + unique indexes.

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Teodor Sigaev <teodor@sigaev.ru>
Cc: Alexander Korotkov <a.korotkov@postgrespro.ru>, Anastasia Lubennikova <a.lubennikova@postgrespro.ru>, Thomas Munro <thomas.munro@enterprisedb.com>, Andrey Borodin <x4mmm@yandex-team.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Anastasia Lubennikova <lubennikovaav@gmail.com>
Date: 2018-03-27T17:15:43Z
Lists: pgsql-hackers 
On Tue, Mar 27, 2018 at 10:07 AM, Teodor Sigaev <teodor@sigaev.ru> wrote:
> Storing number of attributes in now unused t_tid seems to me not so good
> idea. a) it could (and suppose, should) separate patch, at least it's not
> directly connected to covering patch, it could be added even before covering
> patch.

I think that we should do that first. It's not very hard.

> b) I don't like an idea to limiting usage of that field if we can do not
> that. Future usage could use it, for example, for different compression
> technics or something else.

The extra status bits that this would leave within the offset field
can be used for that in the future.

>> * It makes diagnosing issues in the field quite a bit easier. Tools
>> like pg_filedump can do the right thing (Tom mentioned pg_filedump and
>> amcheck specifically). The nbtree IndexTuple format should not need to
>> be interpreted in a context-sensitive way, if we can avoid it.
>
> Both pg_filedump and amcheck could correclty parse any tuple based on
> BTP_LEAF flags and length of tuple.

amcheck doesn't just care about the length of the tuple. It would have
to rely on catalog metadata about this being an INCLUDE index.

-- 
Peter Geoghegan

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