org.apache.druid.segment

Interface ColumnProcessorFactory<T>

All Known Implementing Classes:

PredicateValueMatcherFactory, StringConstantValueMatcherFactory

public interface ColumnProcessorFactory<T>

Class that encapsulates knowledge about how to create "column processors", which are... objects that process columns and want to have type-specific logic. Used by ColumnProcessors.makeProcessor(java.lang.String, org.apache.druid.segment.ColumnProcessorFactory<T>, org.apache.druid.segment.ColumnSelectorFactory). 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.

See Also:

the vectorized version, which uses these, and which is responsible for determining which type of selector to use for a given column, which serves a similar purpose and may be replaced by this in the future, which accepts {@link ColumnSelectorStrategyFactory} and is similar to {@link ColumnProcessors#makeProcessor}

Method Summary

Modifier and Type	Method and Description
ColumnType	defaultType() This default type will be used when the underlying column has an unknown type.
T	makeArrayProcessor(BaseObjectColumnValueSelector<?> selector, ColumnCapabilities columnCapabilities)
T	makeComplexProcessor(BaseObjectColumnValueSelector<?> selector) Create a processor for a complex column.
T	makeDimensionProcessor(DimensionSelector selector, boolean multiValue) Create a processor for a string column.
T	makeDoubleProcessor(BaseDoubleColumnValueSelector selector) Create a processor for a double column.
T	makeFloatProcessor(BaseFloatColumnValueSelector selector) Create a processor for a float column.
T	makeLongProcessor(BaseLongColumnValueSelector selector) Create a processor for a long column.

Method Detail

defaultType

ColumnType defaultType()

This default type will be used when the underlying column has an unknown type. This allows a column processor factory to specify what type it prefers to deal with (the most 'natural' type for whatever it is doing) when all else is equal.

makeDimensionProcessor

T makeDimensionProcessor(DimensionSelector selector,
                         boolean multiValue)

Create a processor for a string column.

Parameters:

selector - dimension selector

multiValue - whether the selector *might* have multiple values

makeFloatProcessor

T makeFloatProcessor(BaseFloatColumnValueSelector selector)

Create a processor for a float column.

Parameters:

selector - float selector

makeDoubleProcessor

T makeDoubleProcessor(BaseDoubleColumnValueSelector selector)

Create a processor for a double column.

Parameters:

selector - double selector

makeLongProcessor

T makeLongProcessor(BaseLongColumnValueSelector selector)

Create a processor for a long column.

Parameters:

selector - long selector

makeArrayProcessor

T makeArrayProcessor(BaseObjectColumnValueSelector<?> selector,
                     @Nullable
                     ColumnCapabilities columnCapabilities)

Parameters:

selector - array selector

columnCapabilities - information about the underlying column to match. Null here just means the capabilities are unknown, and not necessarily indicative that the column doesn't exist

makeComplexProcessor

T makeComplexProcessor(BaseObjectColumnValueSelector<?> selector)

Create a processor for a complex column.

Parameters:

selector - object selector