io.druid.query.groupby.epinephelinae.column

Interface GroupByColumnSelectorStrategy

All Superinterfaces:

ColumnSelectorStrategy

All Known Implementing Classes:

DictionaryBuildingStringGroupByColumnSelectorStrategy, DoubleGroupByColumnSelectorStrategy, FloatGroupByColumnSelectorStrategy, LongGroupByColumnSelectorStrategy, StringGroupByColumnSelectorStrategy

public interface GroupByColumnSelectorStrategy
extends ColumnSelectorStrategy

Contains a collection of query processing methods for type-specific operations used exclusively by GroupByQueryEngineV2. Each GroupByColumnSelectorStrategy is associated with a single dimension.

Field Summary

Fields

Modifier and Type	Field and Description
static int	GROUP_BY_MISSING_VALUE

Method Summary

Modifier and Type	Method and Description
boolean	checkRowIndexAndAddValueToGroupingKey(int keyBufferPosition, Object rowObj, int rowValIdx, ByteBuffer keyBuffer) If rowValIdx is less than the size of rowObj (haven't handled all of the row values): First, read the value at rowValIdx from a rowObj and write that value to the keyBuffer at keyBufferPosition.
int	getGroupingKeySize() Return the size, in bytes, of this dimension's values in the grouping key.
Object	getOnlyValue(ColumnValueSelector selector) Retrieve a single object using the ColumnValueSelector.
void	initColumnValues(ColumnValueSelector selector, int columnIndex, Object[] valuess) Retrieve a row object from the ColumnValueSelector and put it in valuess at columnIndex.
void	initGroupingKeyColumnValue(int keyBufferPosition, int columnIndex, Object rowObj, ByteBuffer keyBuffer, int[] stack) Read the first value within a row values object (e.
void	processValueFromGroupingKey(GroupByColumnSelectorPlus selectorPlus, ByteBuffer key, Map<String,Object> resultMap) Read a value from a grouping key and add it to the group by query result map, using the output name specified in a DimensionSpec.
void	writeToKeyBuffer(int keyBufferPosition, Object obj, ByteBuffer keyBuffer) Write a given object to the keyBuffer at keyBufferPosition.

Field Detail

GROUP_BY_MISSING_VALUE

static final int GROUP_BY_MISSING_VALUE

See Also:

Constant Field Values

Method Detail

getGroupingKeySize

int getGroupingKeySize()

Return the size, in bytes, of this dimension's values in the grouping key. For example, a String implementation would return 4, the size of an int.

Returns:

size, in bytes, of this dimension's values in the grouping key.

processValueFromGroupingKey

void processValueFromGroupingKey(GroupByColumnSelectorPlus selectorPlus,
                                 ByteBuffer key,
                                 Map<String,Object> resultMap)

Read a value from a grouping key and add it to the group by query result map, using the output name specified in a DimensionSpec. An implementation may choose to not add anything to the result map (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

Parameters:

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

resultMap - result map for the group by query being served

key - grouping key

initColumnValues

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

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

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

initGroupingKeyColumnValue

void initGroupingKeyColumnValue(int keyBufferPosition,
                                int columnIndex,
                                Object rowObj,
                                ByteBuffer keyBuffer,
                                int[] stack)

Read the first value within a row values object (e. g. IndexedInts, as the value in a dictionary-encoded string column) and write that value to the keyBuffer at keyBufferPosition. If the row size is 0 (e. g. IndexedInts.size()), write GROUP_BY_MISSING_VALUE instead. If the size of the row is > 0, write 1 to stack[] at columnIndex, otherwise write 0.

Parameters:

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

columnIndex - Index of the column within the row values array

rowObj - Row value object for this column

keyBuffer - grouping key

stack - array containing the current within-row value index for each column

checkRowIndexAndAddValueToGroupingKey

boolean checkRowIndexAndAddValueToGroupingKey(int keyBufferPosition,
                                              Object rowObj,
                                              int rowValIdx,
                                              ByteBuffer keyBuffer)

If rowValIdx is less than the size of rowObj (haven't handled all of the row values): First, read the value at rowValIdx from a rowObj and write that value to the keyBuffer at keyBufferPosition. Then return true Otherwise, return false.

Parameters:

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

rowObj - Row value object for this column (e.g., IndexedInts)

rowValIdx - Index of the current value being grouped on within the row

keyBuffer - grouping key

Returns:

true if rowValIdx < size of rowObj, false otherwise

getOnlyValue

Object getOnlyValue(ColumnValueSelector selector)

Retrieve a single object using the ColumnValueSelector. The reading column must have a single value.

Parameters:

selector - Value selector for a column

Returns:

an object retrieved from the column

writeToKeyBuffer

void writeToKeyBuffer(int keyBufferPosition,
                      Object obj,
                      ByteBuffer keyBuffer)

Write a given object to the keyBuffer at keyBufferPosition.

Parameters:

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

obj - row value object retrieved from getOnlyValue(ColumnValueSelector)

keyBuffer - grouping key