Package 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 and is similar to

Method Summary

Modifier and Type	Method	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