Horton

Re: POC, WIP: OR-clause support for indexes

jian he <jian.universality@gmail.com>

View thread
From: jian he <jian.universality@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Andrei Lepikhov <lepihov@gmail.com>, Alena Rybakina <a.rybakina@postgrespro.ru>, Nikolay Shaplov <dhyan@nataraj.su>, pgsql-hackers@lists.postgresql.org, pgsql-hackers@postgresql.org, Peter Geoghegan <pg@bowt.ie>, Marcos Pegoraro <marcos@f10.com.br>, teodor@sigaev.ru, Peter Eisentraut <peter@eisentraut.org>, Ranier Vilela <ranier.vf@gmail.com>
Date: 2024-10-08T05:11:00Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Make group_similar_or_args() reorder clause list as little as possible

  2. Allow usage of match_orclause_to_indexcol() for joins

  3. Skip not SOAP-supported indexes while transforming an OR clause into SAOP

  4. Remove the wrong assertion from match_orclause_to_indexcol()

  5. Teach bitmap path generation about transforming OR-clauses to SAOP's

  6. Transform OR-clauses to SAOP's during index matching

  7. Fix the value of or_to_any_transform_limit in postgresql.conf.sample

  8. Transform OR clauses to ANY expression

  9. MergeAttributes code deduplication

  10. SEARCH and CYCLE clauses

  11. Improve estimation of OR clauses using extended statistics.

  12. Teach btree to handle ScalarArrayOpExpr quals natively.

  13. Revise collation derivation method and expression-tree representation.

  14. Instead of trying to force WHERE clauses into CNF or DNF normal form,

On Mon, Oct 7, 2024 at 10:06 PM jian he <jian.universality@gmail.com> wrote:
>
> assume v40 is the latest version.

make_bitmap_paths_for_or_group
{
    /*
     * First, try to match the whole group to the one index.
     */
    orargs = list_make1(ri);
    indlist = build_paths_for_OR(root, rel,
                                 orargs,
                                 other_clauses);
    if (indlist != NIL)
    {
        bitmapqual = choose_bitmap_and(root, rel, indlist);
        jointcost = bitmapqual->total_cost;
        jointlist = list_make1(bitmapqual);
    }
    /*
     * Also try to match all containing clauses 'one-by-one.
     */
    foreach(lc, args)
    {
        orargs = list_make1(lfirst(lc));
        indlist = build_paths_for_OR(root, rel,
                                     orargs,
                                     other_clauses);
        if (indlist == NIL)
        {
            splitlist = NIL;
            break;
        }
        bitmapqual = choose_bitmap_and(root, rel, indlist);
}

if other_clauses is not NIL, then "try to match all containing clauses
'one-by-one"
the foreach loop "foreach(lc, args)" will apply other_clauses in
build_paths_for_OR every time.
then splitcost will obviously be higher than jointcost.

if other_clauses is NIL.
"foreach(lc, args)" will have list_length(args) startup cost.
So overall, it looks like jointcost will alway less than splitcost,
the only corner case would be both are zero.

anyway, in make_bitmap_paths_for_or_group,
above line "Pick the best option."  I added:

    if (splitcost <= jointcost && splitcost != 0 && jointcost != 0)
        elog(INFO, "%s:%d splitcost <= jointcost and both is not
zero", __FILE_NAME__, __LINE__);
and the regress tests passed.
That means we don't need to iterate "((BoolExpr *)
ri->orclause)->args"  in make_bitmap_paths_for_or_group
?