Horton

Re: POC: converting Lists into arrays

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-02-25T21:21:00Z
Lists: pgsql-hackers 
Hi,

On 2019-02-25 16:03:43 -0500, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > FWIW, rewrites of this kind can be quite nicely automated using
> > coccinelle [1]. One sometimes needs to do a bit of mop-up with variable
> > names, but otherwise it should be mostly complete.
> 
> 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.

Uhm, we're talking about an invasive proposal from two weekend days
ago. It seems far from crazy to voice our concerns with the silent
breakage you propose. Nor, even if we were obligated to work on an
alternative approach, which we aren't, would it be realistic for us to
have written an alternative implementation within the last few hours,
while also working on our own priorities.

I'm actually quite interested in this topic, both in the sense that it's
great to see work, and in the sense that I'm willing to help with the
effort.

Greetings,

Andres Freund

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.