924060929 opened a new pull request, #65769:
URL: https://github.com/apache/doris/pull/65769
### What problem does this PR solve?
The `nereids_syntax_p0/distribute/shuffle_left_join` regression test is
flaky.
With the nereids distribute planner enabled, the join in this suite can be
planned either as `INNER JOIN(PARTITIONED)` or as a left-to-right
`INNER JOIN(BUCKET_SHUFFLE)` — the aggregated left side shuffled onto the
right
table's storage buckets — and the two candidates are chosen by cost. That
cost
is not stable during the test:
- the scan row count is reported asynchronously after the insert, so an
unreported count clamps to 1 (which favors a partitioned shuffle), while
the
real count favors a bucket shuffle;
- the bucket-shuffle downgrade gate (`isBucketShuffleDownGrade`) turns bucket
shuffle back into a partitioned shuffle when the bucket count is small
relative to the instance count, so the plan also depends on the number of
backends.
As a result the asserted plan flips between `INNER JOIN(PARTITIONED)` and
`INNER JOIN(BUCKET_SHUFFLE)` depending on timing and cluster topology.
The suite is meant to assert the left-to-right bucket shuffle, which saves
one
exchange versus a plain partitioned shuffle. This PR restores that assertion
and
makes it deterministic:
- `analyze table ... with sync` fixes the row count instead of racing the
async
tablet report (the count is then read from the collected column stats);
- `set bucket_shuffle_downgrade_ratio=0` removes the dependency on the
number of
backends.
Verified on a 4-backend cluster: the suite now stably produces
`INNER JOIN(PARTITIONED)` for the legacy-planner leg and
`INNER JOIN(BUCKET_SHUFFLE)` for the distribute-planner leg across
parallelism
1/4/8 and both before/after stats reporting; the suite was run 3 times, all
green.
### Release note
None
### Check List (For Committer)
- [x] Regression test
- [ ] Unit Test
- [ ] Manual test (add detailed scripts or steps below)
- [x] No need to test or manual test. Reason: regression-test-only change.
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