Horton

Re: Optimizing nbtree ScalarArrayOp execution, allowing multi-column ordered scans, skip scan

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Jeff Davis <pgsql@j-davis.com>, benoit <benoit@hopsandfork.com>, Alexander Korotkov <aekorotkov@gmail.com>
Date: 2024-04-08T01:50:40Z
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. Move nbtree preprocessing into new .c file.

  2. Fix nbtree lookahead overflow bug.

  3. Remove unneeded nbtree array preprocessing assert.

  4. Don't try to fix eliminated nbtree array scan keys.

  5. Remove redundant nbtree preprocessing assertions.

  6. Avoid extra lookups with nbtree array inequalities.

  7. Enhance nbtree ScalarArrayOp execution.

  8. Improvements and fixes for e0b1ee17dc

  9. Skip checking of scan keys required for directional scan in B-tree

  10. Fix btmarkpos/btrestrpos array key wraparound bug.

  11. Add nbtree high key "continuescan" optimization.

  12. Consider secondary factors during nbtree splits.

  13. Make heap TID a tiebreaker nbtree index column.

  14. Fix planning of btree index scans using ScalarArrayOpExpr quals.

  15. Fix btree stop-at-nulls logic properly.

  16. Teach btree to handle ScalarArrayOpExpr quals natively.

Peter Geoghegan <pg@bowt.ie> writes:
> The assertions in question are arguably redundant. There are very
> similar assertions just a little earlier on, as we initially set up
> the array stuff (right before _bt_compare_scankey_args is called).
> I'll just remove the "Assert(xform[j].ikey == array->scan_key)"
> assertion that Coverity doesn't like, in addition to the
> "Assert(!array || array->scan_key == i)" assertion, on the grounds
> that they're redundant.

If you're doing that, then surely

                    if (j != (BTEqualStrategyNumber - 1) ||
                        !(xform[j].skey->sk_flags & SK_SEARCHARRAY))
                    {
                        ...
                    }
                    else
                    {
                        Assert(j == (BTEqualStrategyNumber - 1));
                        Assert(xform[j].skey->sk_flags & SK_SEARCHARRAY);
                        Assert(xform[j].ikey == array->scan_key);
                        Assert(!(cur->sk_flags & SK_SEARCHARRAY));
                    }

those first two Asserts are redundant with the "if" as well.

			regards, tom lane