Package io.github.flink.gcp.connector.spanner.source

Class SpannerSource

java.lang.Object
io.github.flink.gcp.connector.spanner.source.SpannerSource
@Public public final class SpannerSource extends Object
Reads rows from a Cloud Spanner database. 

 Source<Singer, ?, ?> source =
         SpannerSource.<Singer>builder()
                 .database(DatabaseDestination.of("my-project", "my-instance", "my-db"))
                 .readOperation(
                         SpannerReadOperation.query(
                                 Statement.of("SELECT id, name FROM singers")))
                 .deserializer(mySingerDeserializer)
                 .build();

The read is bounded: the source reads the rows the operation names, at one snapshot, and finishes. That is not the same as batch-only — a bounded source runs inside a streaming pipeline and simply ends, which is what makes reading a Spanner table and joining it against an unbounded stream work.

Every subtask reads the same snapshot. The source asks Spanner to divide the read into partitions at one timestamp, and each subtask rejoins that transaction to read the partitions it was given. There is no column to split on and no bounds to supply: where the divisions fall is the service's decision, made from how the data is actually stored.

  • Method Details

    • builder

      public static <T> SpannerSourceBuilder<T> builder()
      Returns a builder for a Spanner batch source.

      The source returned by the builder implements LineageVertexProvider. Explicit table and index reads identify the base table in namespace spanner://project:instance, with name database.table; a native API name already containing its schema retains that qualification. Arbitrary SQL has an empty dataset list. Extraction uses configuration only and never evaluates a read resolver or deserializer, loads credentials, or opens a client. Flink 2.x extracts this metadata automatically; Flink 1.20 supports direct inspection but not native listener delivery.

      Type Parameters:
      T - the record type produced
      Returns:
      the builder