Horton

Re: POC: converting Lists into arrays

Jesper Pedersen <jesper.pedersen@redhat.com>

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From: Jesper Pedersen <jesper.pedersen@redhat.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David Rowley <david.rowley@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-07-01T19:18:02Z
Lists: pgsql-hackers 
Hi,

On 7/1/19 2:44 PM, Tom Lane wrote:
> Yup, here's a rebase against HEAD (and I also find that check-world shows
> no problems).

Thanks - no further comments.

>  This is pretty much of a pain to maintain, since it changes
> the API for lnext() which is, um, a bit invasive.  I'd like to make a
> decision pretty quickly on whether we're going to do this, and either
> commit this patch or abandon it.
> 

IMHO it is an improvement over the existing API.

>> There is some unneeded MemoryContext stuff in async.c's
>> pg_listening_channels() which should be cleaned up.
> 
> Yeah, there's a fair amount of follow-on cleanup that could be undertaken
> afterwards, but I've wanted to keep the patch's footprint as small as
> possible for the moment.  Assuming we pull the trigger, I'd then go look
> at removing the planner's duplicative lists+arrays for RTEs and such as
> the first cleanup step.  But thanks for the pointer to async.c, I'll
> check that too.
> 

Yeah, I only called out the async.c change, as that function isn't 
likely to change in any of the follow up patches.

Best regards,
  Jesper

Commits

  1. Remove EState.es_range_table_array.

  2. Rationalize use of list_concat + list_copy combinations.

  3. Cosmetic improvements in setup of planner's per-RTE arrays.

  4. Make better use of the new List implementation in a couple of places

  5. Fix sepgsql test results for commit d97b714a2.

  6. Avoid using lcons and list_delete_first where it's easy to do so.

  7. Remove lappend_cell...() family of List functions.

  8. Clean up some ad-hoc code for sorting and de-duplicating Lists.

  9. Redesign the API for list sorting (list_qsort becomes list_sort).

  10. Remove dead code.

  11. Represent Lists as expansible arrays, not chains of cons-cells.

  12. Standardize some more loops that chase down parallel lists.

  13. Reimplement the linked list data structure used throughout the backend.