Package org.apache.spark.sql.connector.catalog

Interface Relation

All Known Subinterfaces:
StagedTable, SupportsAtomicPartitionManagement, SupportsDelete, SupportsDeleteV2, SupportsIndex, SupportsMetadataColumns, SupportsPartitionManagement, SupportsRead, SupportsRowLevelOperations, SupportsSchemaEvolution, SupportsWrite, Table, TruncatableTable
All Known Implementing Classes:
DelegatingTable, View
@Evolving public interface Relation
A relation in a catalog: either a Table or a View. This is the common type returned by RelationCatalog.loadRelation(org.apache.spark.sql.connector.catalog.Identifier) so a catalog that exposes both kinds can answer a single read in one round trip; callers discriminate with instanceof Table / instanceof View.

The two kinds are deliberately asymmetric, mirroring how Spark treats them: a Table is an object Spark reads from and writes to, while a View carries only metadata (Spark expands its query text at read time and never builds a view object). Modeling both as siblings of Relation -- rather than smuggling a view through the Table surface -- keeps table-only concepts (partitioning, constraints, scans, writes) off the view side.

In practice the only two kinds are Table and View. Relation is left un-sealed because Table is itself an open interface (so a closed hierarchy would add little) and because a sealed Java interface trips Scala's pattern-match analysis.

Since:
4.2.0

  • Method Summary

    Modifier and Type
    Method
    Description
    Column[]
    columns()
    The columns of this relation.
    Map<String,String>
    properties()
    The string map of properties of this relation.

  • Method Details

    • columns

      Column[] columns()
      The columns of this relation.

    • properties

      Map<String,String> properties()
      The string map of properties of this relation.