RowIdSupplier (druid-processing 28.0.1 API)

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 Description
  
  static long INIT
  A number that will never be returned from getRowId().
- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method 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.