rohangarg commented on code in PR #12225:
URL: https://github.com/apache/druid/pull/12225#discussion_r878898786
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processing/src/main/java/org/apache/druid/segment/join/JoinableFactoryWrapper.java:
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@@ -276,28 +272,31 @@ static Optional<Filter> convertJoinToFilter(
&& clause.getCondition().getEquiConditions().size() > 0) {
final List<Filter> filters = new ArrayList<>();
int numValues = maxNumFilterValues;
+ boolean dropClause = true;
for (final Equality condition :
clause.getCondition().getEquiConditions()) {
final String leftColumn =
condition.getLeftExpr().getBindingIfIdentifier();
if (leftColumn == null) {
- return Optional.empty();
+ return new NonnullPair<>(Optional.empty(), false);
}
- final Optional<Set<String>> columnValuesForFilter =
-
clause.getJoinable().getNonNullColumnValuesIfAllUnique(condition.getRightColumn(),
numValues);
+ Joinable.ColumnValuesWithUniqueFlag columnValuesWithUniqueFlag =
clause.getJoinable().getNonNullColumnValues(condition.getRightColumn(),
numValues);
+ if (columnValuesWithUniqueFlag.getColumnValues().isEmpty()) {
+ dropClause = false;
+ continue;
+ }
- if (columnValuesForFilter.isPresent()) {
- numValues -= columnValuesForFilter.get().size();
- filters.add(Filters.toFilter(new InDimFilter(leftColumn,
columnValuesForFilter.get())));
- } else {
- return Optional.empty();
+ numValues -= columnValuesWithUniqueFlag.getColumnValues().size();
+ filters.add(Filters.toFilter(new InDimFilter(leftColumn,
columnValuesWithUniqueFlag.getColumnValues())));
+ if (!columnValuesWithUniqueFlag.isAllUnique()) {
+ dropClause = false;
}
}
- return Optional.of(Filters.and(filters));
+ return new NonnullPair<>(filters.isEmpty() ? Optional.empty() :
Optional.of(Filters.and(filters)), dropClause);
Review Comment:
> Will we ever get filters = Optional.empty() and dropClause = true? If so
what is the expectation in that case?
Yes, that can happen if the joinableClause has conditions on columns which
only have nulls in it. Currently, in such a case I add a `FalseFilter` in place
of the joinable clause - does that seem ok?
> IMO, the NonnullPair is tough to think about here, so a special class
would be better. That way it could have some javadocs about the expectations.
Its constructor should also do any relevant invariant checks.
Yes, completely agree. 👍 Thanks for the suggestion - I've made a holder
instead of a pair and added documentation regarding its semantics.
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