clintropolis commented on a change in pull request #10767:
URL: https://github.com/apache/druid/pull/10767#discussion_r560893111
##########
File path:
processing/src/main/java/org/apache/druid/segment/VectorColumnProcessorFactory.java
##########
@@ -22,34 +22,59 @@
import org.apache.druid.segment.column.ColumnCapabilities;
import org.apache.druid.segment.vector.MultiValueDimensionVectorSelector;
import org.apache.druid.segment.vector.SingleValueDimensionVectorSelector;
+import org.apache.druid.segment.vector.VectorObjectSelector;
import org.apache.druid.segment.vector.VectorValueSelector;
/**
* Class that encapsulates knowledge about how to create vector column
processors. Used by
- * {@link DimensionHandlerUtils#makeVectorProcessor}.
+ * {@link ColumnProcessors#makeVectorProcessor}.
*
- * Unlike {@link ColumnProcessorFactory}, this interface does not have a
"defaultType" method. The default type is
- * always implicitly STRING. It also does not have a "makeComplexProcessor"
method; instead, complex-typed columns
- * are fed into "makeSingleValueDimensionProcessor". This behavior may change
in the future to better align
- * with {@link ColumnProcessorFactory}.
+ * Column processors can be any type "T". The idea is that a
ColumnProcessorFactory embodies the logic for wrapping
+ * and processing selectors of various types, and so enables nice code design,
where type-dependent code is not
+ * sprinkled throughout.
+ *
+ * Unlike {@link ColumnProcessorFactory}, this interface does not have a
"defaultType" method, because vector
+ * column types are always known, so it isn't necessary.
*
* @see ColumnProcessorFactory the non-vectorized version
*/
public interface VectorColumnProcessorFactory<T>
{
+ /**
+ * Called when {@link ColumnCapabilities#getType()} is STRING and the
underlying column always has a single value
+ * per row.
+ */
T makeSingleValueDimensionProcessor(
ColumnCapabilities capabilities,
SingleValueDimensionVectorSelector selector
);
+ /**
+ * Called when {@link ColumnCapabilities#getType()} is STRING and the
underlying column may have multiple values
+ * per row.
+ */
T makeMultiValueDimensionProcessor(
ColumnCapabilities capabilities,
MultiValueDimensionVectorSelector selector
);
+ /**
+ * Called when {@link ColumnCapabilities#getType()} is FLOAT.
+ */
T makeFloatProcessor(ColumnCapabilities capabilities, VectorValueSelector
selector);
+ /**
+ * Called when {@link ColumnCapabilities#getType()} is DOUBLE.
+ */
T makeDoubleProcessor(ColumnCapabilities capabilities, VectorValueSelector
selector);
+ /**
+ * Called when {@link ColumnCapabilities#getType()} is LONG.
+ */
T makeLongProcessor(ColumnCapabilities capabilities, VectorValueSelector
selector);
+
+ /**
+ * Called when {@link ColumnCapabilities#getType()} is COMPLEX.
+ */
+ T makeComplexProcessor(ColumnCapabilities capabilities, VectorObjectSelector
selector);
Review comment:
Since this isn't actually specific to complex columns, can this be
called `makeObjectProcessor`? I have the same method signature except with that
name added to this class in #10613, there to support using object selectors for
string expression virtual columns which are not dictionary encoded.
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