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: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-02-28T21:49:31Z
Lists: pgsql-hackers

Attachments

Here's a rebased version of the main patch.

David Rowley <david.rowley@2ndquadrant.com> writes:
> The only thing that I did to manage to speed the patch up was to ditch
> the additional NULL test in lnext().  I don't see why that's required
> since lnext(NULL) would have crashed with the old implementation.

I adopted this idea.  I think at one point where I was fooling with
different implementations for foreach(), it was necessary that lnext()
be cool with a NULL input; but as things stand now, it's not.

I haven't done anything else in the performance direction, but am
planning to play with that next.

I did run through all the list_delete_foo callers and fix the ones
that were still busted.  I also changed things so that with
DEBUG_LIST_MEMORY_USAGE enabled, list deletions would move the data
arrays around, in hopes of catching more stale-pointer problems.
Depressingly, check-world still passed with that added, even before
I'd fixed the bugs I found by inspection.  This does not speak well
for the coverage of our regression tests.

			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.