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

Interface GroupByColumnSelectorStrategy

    • Field Detail

      • GROUP_BY_MISSING_VALUE

        static final int GROUP_BY_MISSING_VALUE
        Index to indicate the absence of a key in the dictionary
        See Also:
        Constant Field Values

    • Method Detail

      • getGroupingKeySizeBytes

        int getGroupingKeySizeBytes()
        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,
                                 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. 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
        Parameters:
        selectorPlus - dimension info containing the key offset, value selector, and dimension spec
        resultRow - result row for the group by query being served
        key - grouping key
        keyBufferPosition - buffer position for the grouping key, added to support chaining multiple ColumnSelectorStrategy

      • initColumnValues

        @CheckReturnValue
int 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
        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.

      • initGroupingKeyColumnValue

        void initGroupingKeyColumnValue​(int keyBufferPosition,
                                int dimensionIndex,
                                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.
        dimensionIndex - Index of this dimension within the stack 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. This method assumes that the size increase associated with the dictionary building has occurred already when calling initColumnValues(org.apache.druid.segment.ColumnValueSelector, int, java.lang.Object[]) 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

      • writeToKeyBuffer

        @CheckReturnValue
int writeToKeyBuffer​(int keyBufferPosition,
                     ColumnValueSelector selector,
                     ByteBuffer keyBuffer)
        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.
        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

        Grouper.BufferComparator bufferComparator​(int keyBufferPosition,
                                          @Nullable
                                          StringComparator stringComparator)
        Return BufferComparator for values written using this strategy when limit is pushed down to segment scan.
        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