Package org.apache.druid.query.rowsandcols.concrete

Class ColumnHolderRACColumn

java.lang.Object
org.apache.druid.query.rowsandcols.concrete.ColumnHolderRACColumn
All Implemented Interfaces:
Closeable, AutoCloseable, Column
public class ColumnHolderRACColumn extends Object implements Column, Closeable
Implements a RowsAndColumns column based on a ColumnHolder. There is a bit of an impedence mis-match between these interfaces in that the ColumnHolder gets at the values of a row by using a BaseColumn which in turn hands off to `ColumnValueSelector` to actually build the thing. The ColumnAccessor from RowsAndColumns, however, believes that it can provide effectively direct access to values.

It would be really good to eventually reach down and interact directly with the columns rather than doing this round-about stuff.

This implementation is also very bad with Objects and data types, it masterfully avoids almost every optimization that we have in place. This should also be revisited at some point in time.

  • Constructor Details

  • Method Details

    • toAccessor

      @Nonnull public ColumnAccessor toAccessor()
      Description copied from interface: Column
      Returns the column as a ColumnAccessor. Semantically, this would be equivalent to calling Column.as(ColumnAccessor.class). However, being able to implement this interface is part of the explicit contract of implementing this interface, so instead of relying on Column.as(java.lang.Class<? extends T>) which allows for returning null, we define a top-level method that should never return null.
      Specified by:
      toAccessor in interface Column
      Returns:
      a ColumnAccessor representation of the column, this should never return null.

    • as

      @Nullable public <T> T as(Class<? extends T> clazz)
      Description copied from interface: Column
      Asks the Column to return itself as a concrete implementation of a specific interface. The interface asked for will tend to be a semantically-meaningful interface. This method allows the calling code to interrogate the Column object about whether it can offer a meaningful optimization of the semantic interface. If a Column cannot do anything specifically optimal for the interface requested, it should return null instead of trying to come up with its own default implementation.
      Specified by:
      as in interface Column
      Type Parameters:
      T - The interface that the calling code wants a concrete implementation of
      Parameters:
      clazz - A class object representing the interface that the calling code wants a concrete implementation of
      Returns:
      A concrete implementation of the interface, or null if there is no meaningful optimization to be had through a local implementation of the interface.

    • close

      public void close() throws IOException
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException

    • getBaseColumn

      public BaseColumn getBaseColumn()