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: jesper.pedersen@redhat.com
Cc: David Rowley <david.rowley@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-07-01T18:44:45Z
Lists: pgsql-hackers

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Jesper Pedersen <jesper.pedersen@redhat.com> writes:
> This needs a rebase. After that check-world passes w/ and w/o 
> -DDEBUG_LIST_MEMORY_USAGE.

Yup, here's a rebase against HEAD (and I also find that check-world shows
no problems).  This is pretty much of a pain to maintain, since it changes
the API for lnext() which is, um, a bit invasive.  I'd like to make a
decision pretty quickly on whether we're going to do this, and either
commit this patch or abandon it.

> There is some unneeded MemoryContext stuff in async.c's 
> pg_listening_channels() which should be cleaned up.

Yeah, there's a fair amount of follow-on cleanup that could be undertaken
afterwards, but I've wanted to keep the patch's footprint as small as
possible for the moment.  Assuming we pull the trigger, I'd then go look
at removing the planner's duplicative lists+arrays for RTEs and such as
the first cleanup step.  But thanks for the pointer to async.c, I'll
check that too.

			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.