Horton

Re: POC: converting Lists into arrays

David Rowley <david.rowley@2ndquadrant.com>

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-03-05T00:16:42Z
Lists: pgsql-hackers 
On Tue, 5 Mar 2019 at 12:54, Andres Freund <andres@anarazel.de> wrote:
> Yes, I think you have a point that progress here would be good and that
> it's worth some pain. But the names will make even less sense if we just
> shunt in an array based approach under the already obscure list
> API.

If we feel strongly about fixing that then probably it would be as
simple as renaming the functions and adding some macros with the old
names and insisting that all new or changed code use the functions and
not the macro wrappers. That could be followed up by a final sweep in
N years time when the numbers have dwindled to a low enough level. All
that code mustn't be getting modified anyway, so not much chance
backpatching pain.

I see length() finally died in a similar way in Tom's patch.  Perhaps
doing this would have people consider lcons more carefully before they
use it over lappend.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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.