gianm commented on a change in pull request #8209: add mechanism to control
filter optimization in historical query processing
URL: https://github.com/apache/incubator-druid/pull/8209#discussion_r310864811
##########
File path: processing/src/main/java/org/apache/druid/query/filter/Filter.java
##########
@@ -129,4 +130,19 @@ default boolean canVectorizeMatcher()
{
return false;
}
+
+ /**
+ * Set of columns used by a filter
+ */
+ Set<String> getRequiredColumns();
+
+ /**
+ * Determine if a filter *should* use a bitmap index based on information
collected from the supplied
+ * {@link BitmapIndexSelector}. This method differs from {@link
#supportsBitmapIndex(BitmapIndexSelector)} in that
+ * the former only indicates if a bitmap index is available and {@link
#getBitmapIndex(BitmapIndexSelector)} may be
+ * used. This method, by default, will consider a {@link FilterTuning} to
make decisions about when to use an
+ * available index. Override this method in a {@link Filter} implementation
when {@link FilterTuning} alone is not
+ * adequate for making this decision.
+ */
Review comment:
I'd reword slightly. This method doesn't do anything by default anymore (it
did in an earlier version). Maybe cut the last two sentences, and replace with:
> Implementations of this methods typically consider a {@link FilterTuning}
to make decisions about when to use an available index.
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