Package org.apache.drill.metastore.operate

Interface Read<T>

Type Parameters:
T - component unit type
All Known Implementing Classes:
AbstractRead, IcebergRead, MongoRead, RdbmsRead
public interface Read<T>
Drill Metastore Read interface contains methods to be implemented in order to provide read functionality from the Metastore component.

  • Method Details

    • metadataTypes

      Read<T> metadataTypes(Set<MetadataType> metadataTypes)
      Provides set of metadata types to be read. Note: providing at least one metadata type is required. If all metadata types should be read, MetadataType.ALL can be passed.
      Parameters:
      metadataTypes - set of metadata types
      Returns:
      current instance of Read interface implementation

    • metadataType

      default Read<T> metadataType(MetadataType... metadataType)

    • filter

      Read<T> filter(FilterExpression filter)
      Provides filter expression by which metastore component data will be filtered. If filter expression is not indicated, all Metastore component data will be read.
      Parameters:
      filter - filter expression
      Returns:
      current instance of Read interface implementation

    • columns

      Read<T> columns(List<MetastoreColumn> columns)
      Provides list of columns to be read from Metastore component. If no columns are indicated, all columns will be read. Depending on Metastore component implementation, providing list of columns to be read, can improve retrieval performance.
      Parameters:
      columns - list of columns to be read from Metastore component
      Returns:
      current instance of Read interface implementation

    • columns

      default Read<T> columns(MetastoreColumn... columns)

    • execute

      List<T> execute()
      Executes read operation from Metastore component, returns obtained result in a form of list of component units which later can be transformed into suitable format.
      Returns:
      list of component units