org.apache.druid.query.groupby.epinephelinae.column

Class DictionaryBuildingStringGroupByColumnSelectorStrategy

java.lang.Object

org.apache.druid.query.groupby.epinephelinae.column.StringGroupByColumnSelectorStrategy

org.apache.druid.query.groupby.epinephelinae.column.DictionaryBuildingStringGroupByColumnSelectorStrategy

All Implemented Interfaces:

ColumnSelectorStrategy, GroupByColumnSelectorStrategy

public class DictionaryBuildingStringGroupByColumnSelectorStrategy
extends StringGroupByColumnSelectorStrategy

A String strategy that builds an internal String<->Integer dictionary for DimensionSelectors that return false for nameLookupPossibleInAdvance()

Constructor Summary

Constructors

Constructor and Description
DictionaryBuildingStringGroupByColumnSelectorStrategy()

Method Summary

Modifier and Type	Method and Description
Grouper.BufferComparator	bufferComparator(int keyBufferPosition, StringComparator stringComparator) Return BufferComparator for values written using this strategy when limit is pushed down to segment scan.
int	initColumnValues(ColumnValueSelector selector, int columnIndex, Object[] valuess) Retrieve a row object from the ColumnValueSelector and put it in valuess at columnIndex.
void	processValueFromGroupingKey(GroupByColumnSelectorPlus selectorPlus, ByteBuffer key, ResultRow resultRow, int keyBufferPosition) Read a value from a grouping key and add it to the group by query result row, using the output name specified in a DimensionSpec.
void	reset() Reset any internal state held by this selector.
int	writeToKeyBuffer(int keyBufferPosition, ColumnValueSelector selector, ByteBuffer keyBuffer) Write a single object from the given selector to the keyBuffer at keyBufferPosition.

Methods inherited from class org.apache.druid.query.groupby.epinephelinae.column.StringGroupByColumnSelectorStrategy

checkRowIndexAndAddValueToGroupingKey, getGroupingKeySize, initGroupingKeyColumnValue, writeToKeyBuffer

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DictionaryBuildingStringGroupByColumnSelectorStrategy

public DictionaryBuildingStringGroupByColumnSelectorStrategy()

Method Detail

processValueFromGroupingKey

public void processValueFromGroupingKey(GroupByColumnSelectorPlus selectorPlus,
                                        ByteBuffer key,
                                        ResultRow resultRow,
                                        int keyBufferPosition)

Description copied from interface: GroupByColumnSelectorStrategy

Read a value from a grouping key and add it to the group by query result row, using the output name specified in a DimensionSpec. An implementation may choose to not add anything to the result row (e.g., as the String implementation does for empty rows) selectorPlus provides access to: - the keyBufferPosition offset from which to read the value - the dimension value selector - the DimensionSpec for this dimension from the query

Specified by:

processValueFromGroupingKey in interface GroupByColumnSelectorStrategy

Overrides:

processValueFromGroupingKey in class StringGroupByColumnSelectorStrategy

Parameters:

selectorPlus - dimension info containing the key offset, value selector, and dimension spec

key - grouping key

resultRow - result row for the group by query being served

keyBufferPosition - buffer position for the grouping key, added to support chaining multiple ColumnSelectorStrategy

initColumnValues

public int initColumnValues(ColumnValueSelector selector,
                            int columnIndex,
                            Object[] valuess)

Description copied from interface: GroupByColumnSelectorStrategy

Retrieve a row object from the ColumnValueSelector and put it in valuess at columnIndex.

Specified by:

initColumnValues in interface GroupByColumnSelectorStrategy

Overrides:

initColumnValues in class StringGroupByColumnSelectorStrategy

Parameters:

selector - Value selector for a column.

columnIndex - Index of the column within the row values array

valuess - Row values array, one index per column

Returns:

estimated increase in internal state footprint, in bytes, as a result of this operation. May be zero if memory did not increase as a result of this operation. Will not be negative.

writeToKeyBuffer

public int writeToKeyBuffer(int keyBufferPosition,
                            ColumnValueSelector selector,
                            ByteBuffer keyBuffer)

Description copied from interface: GroupByColumnSelectorStrategy

Write a single object from the given selector to the keyBuffer at keyBufferPosition. The reading column must have a single value. The position of the keyBuffer may be modified.

Specified by:

writeToKeyBuffer in interface GroupByColumnSelectorStrategy

Overrides:

writeToKeyBuffer in class StringGroupByColumnSelectorStrategy

Parameters:

keyBufferPosition - starting offset for this column's value within the grouping key

selector - selector to retrieve row value object from

keyBuffer - grouping key

Returns:

estimated increase in internal state footprint, in bytes, as a result of this operation. May be zero if memory did not increase as a result of this operation. Will not be negative.

bufferComparator

public Grouper.BufferComparator bufferComparator(int keyBufferPosition,
                                                 @Nullable
                                                 StringComparator stringComparator)

Description copied from interface: GroupByColumnSelectorStrategy

Return BufferComparator for values written using this strategy when limit is pushed down to segment scan.

Specified by:

bufferComparator in interface GroupByColumnSelectorStrategy

Overrides:

bufferComparator in class StringGroupByColumnSelectorStrategy

Parameters:

keyBufferPosition - starting offset for this column's value within the grouping key

stringComparator - stringComparator from LimitSpec for this column. If this is null, implementations will use the StringComparators.LEXICOGRAPHIC comparator.

Returns:

BufferComparator for comparing values written

reset

public void reset()

Description copied from interface: GroupByColumnSelectorStrategy

Reset any internal state held by this selector. After this method is called, any row objects or key objects generated by any methods of this class must be considered unreadable. Calling GroupByColumnSelectorStrategy.processValueFromGroupingKey(org.apache.druid.query.groupby.epinephelinae.column.GroupByColumnSelectorPlus, java.nio.ByteBuffer, org.apache.druid.query.groupby.ResultRow, int) on that memory has undefined behavior.

Specified by:

reset in interface GroupByColumnSelectorStrategy

Overrides:

reset in class StringGroupByColumnSelectorStrategy