Horton

Re: POC: converting Lists into arrays

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, Jesper Pedersen <jesper.pedersen@redhat.com>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-08-12T15:25:37Z
Lists: pgsql-hackers 
David Rowley <david.rowley@2ndquadrant.com> writes:
> On Fri, 9 Aug 2019 at 04:24, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Has anyone got further thoughts about naming around list_concat
>> and friends?
>> If not, I'm inclined to go ahead with the concat-improvement patch as
>> proposed in [1], modulo the one improvement David spotted.
>> [1] https://www.postgresql.org/message-id/6704.1563739305@sss.pgh.pa.us

> I'm okay with the patch once that one improvement is done.

Pushed with that fix.

> I think if we want to think about freeing the 2nd input List then we
> can do that in another commit. Removing the redundant list_copy()
> calls seems quite separate from that.

The reason I was holding off is that this patch obscures the distinction
between places that needed to preserve the second input (which were
doing list_copy on it) and those that didn't (and weren't).  If somebody
wants to rethink the free-second-input business they'll now have to do
a bit of software archaeology to determine which calls to change.  But
I don't think we're going to bother.

			regards, tom lane

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.