Horton

Re: POC: converting Lists into arrays

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-02-25T21:21:30Z
Lists: pgsql-hackers 
On Mon, Feb 25, 2019 at 1:04 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I'm getting slightly annoyed by arguments that reject a live, workable
> patch in favor of pie-in-the-sky proposals.  Both you and Robert seem
> to be advocating solutions that don't exist and would take a very large
> amount of work to create.  If you think differently, let's see a patch.

ISTM that we should separate the question of whether or not the List
API needs to continue to work without needing to change code in third
party extensions from the question of whether or not the List API
needs to be replaced whole cloth. These are not exactly independent
questions, but they don't necessarily need to be discussed all at
once.

Andres said that he doesn't like the pg_list.h API. It's not pretty,
but is it really that bad?

The List implementation claims to be generic, but it's not actually
that generic. It has to work as a Node. It's not quite fair to say
that it's confusing without acknowledging that pg_list.h is special to
query processing.

-- 
Peter Geoghegan

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.