Package org.apache.cassandra.cql3.selection

Class Selector

java.lang.Object
org.apache.cassandra.cql3.selection.Selector
Direct Known Subclasses:
SimpleSelector, TermSelector, VectorSelector
public abstract class Selector extends Object
A Selector is used to convert the data returned by the storage engine into the data requested by the user. They correspond to the <selector> elements from the select clause.

Since the introduction of aggregation, Selectors cannot be called anymore by multiple threads as they have an internal state.

  • Field Details

  • Constructor Details

  • Method Details

    • kind

      public final Selector.Kind kind()
      Returns the Selector kind.
      Returns:
      the Selector kind

    • addFetchedColumns

      public abstract void addFetchedColumns(ColumnFilter.Builder builder)
      Add to the provided builder the column (and potential subselections) to fetch for this selection.
      Parameters:
      builder - the builder to add columns and subselections to.

    • addInput

      public abstract void addInput(Selector.InputRow input)
      Add the current value from the specified ResultSetBuilder.
      Parameters:
      input - the input row
      Throws:
      InvalidRequestException - if a problem occurs while adding the input row

    • getOutput

      public abstract ByteBuffer getOutput(ProtocolVersion protocolVersion) throws InvalidRequestException
      Returns the selector output.
      Parameters:
      protocolVersion - protocol version used for serialization
      Returns:
      the selector output
      Throws:
      InvalidRequestException - if a problem occurs while computing the output value

    • getWritetimes

      protected org.apache.cassandra.cql3.selection.ColumnTimestamps getWritetimes(ProtocolVersion protocolVersion)

    • getTTLs

      protected org.apache.cassandra.cql3.selection.ColumnTimestamps getTTLs(ProtocolVersion protocolVersion)

    • getType

      public abstract AbstractType<?> getType()
      Returns the Selector output type.
      Returns:
      the Selector output type.

    • reset

      public abstract void reset()
      Reset the internal state of this Selector.

    • isTerminal

      public boolean isTerminal()
      A selector is terminal if it doesn't require any input for it's output to be computed, i.e. if getOutput(org.apache.cassandra.transport.ProtocolVersion) result doesn't depend of addInput(org.apache.cassandra.cql3.selection.Selector.InputRow). This is typically the case of a constant value or functions on constant values.

    • validateForGroupBy

      public void validateForGroupBy()
      Checks that this selector is valid for GROUP BY clause.

    • serializedSize

      protected abstract int serializedSize(int version)

    • serialize

      protected abstract void serialize(DataOutputPlus out, int version) throws IOException
      Throws:
      IOException

    • writeType

      protected static void writeType(DataOutputPlus out, AbstractType<?> type) throws IOException
      Throws:
      IOException

    • sizeOf

      protected static int sizeOf(AbstractType<?> type)