org.apache.druid.segment

Interface RowIdSupplier

All Known Implementing Classes:

FrameColumnSelectorFactory, QueryableIndexColumnSelectorFactory

public interface RowIdSupplier

Returned by ColumnSelectorFactory.getRowIdSupplier(). Allows users of ColumnSelectorFactory to cache objects returned by their selectors.

Field Summary

Fields

Modifier and Type	Field and Description
static long	INIT A number that will never be returned from getRowId().

Method Summary

Modifier and Type	Method and Description
long	getRowId() Returns a number that uniquely identifies the current position of some underlying cursor.

Field Detail

INIT

static final long INIT

A number that will never be returned from getRowId(). Useful for initialization.

See Also:

Constant Field Values

Method Detail

getRowId

long getRowId()

Returns a number that uniquely identifies the current position of some underlying cursor. This is useful for caching: it is safe to assume nothing has changed in the selector as long as the row ID stays the same. Row IDs do not need to be contiguous or monotonic. They need not have any meaning. In particular: they may not be row *numbers* (row number 0 may have any arbitrary row ID). Valid row IDs are always nonnegative.