Horton

Re: POC: converting Lists into arrays

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Bruce Momjian <bruce@momjian.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, David Rowley <david.rowley@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-03-04T22:08:36Z
Lists: pgsql-hackers 
On Mon, Mar 4, 2019 at 2:04 PM Bruce Momjian <bruce@momjian.us> wrote:
> On Mon, Mar  4, 2019 at 12:44:41PM -0500, Robert Haas wrote:
> > I think that's a separate but also promising thing to attack, and I
> > agree that it'd take a lot of work to get there.  I don't think that
> > the problem with either parse-tree-copying or list usage is that no
> > performance benefits are to be had; I think it's that the amount of
> > work required to get those benefits is pretty large.  If it were
> > otherwise, somebody likely would have done it before now.
>
> Stupid question, but do we use any kind of reference counter to know if
> two subsystems look at a structure, and a copy is required?

No, but I wonder if we could use Valgrind to enforce rules about who
has the right to scribble on what, when. That could make it a lot
easier to impose a new rule.

-- 
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.