Package org.apache.iceberg.spark.procedures

Class CreateChangelogViewProcedure

  • All Implemented Interfaces:
    Procedure
    public class CreateChangelogViewProcedure
extends java.lang.Object
    A procedure that creates a view for changed rows.

    The procedure removes the carry-over rows by default. If you want to keep them, you can set "remove_carryovers" to be false in the options.

    The procedure doesn't compute the pre/post update images by default. If you want to compute them, you can set "compute_updates" to be true in the options.

    Carry-over rows are the result of a removal and insertion of the same row within an operation because of the copy-on-write mechanism. For example, given a file which contains row1 (id=1, data='a') and row2 (id=2, data='b'). A copy-on-write delete of row2 would require erasing this file and preserving row1 in a new file. The changelog table would report this as (id=1, data='a', op='DELETE') and (id=1, data='a', op='INSERT'), despite it not being an actual change to the table. The procedure finds the carry-over rows and removes them from the result.

    Pre/post update images are converted from a pair of a delete row and an insert row. Identifier columns are used for determining whether an insert and a delete record refer to the same row. If the two records share the same values for the identity columns they are considered to be before and after states of the same row. You can either set identifier fields in the table schema or input them as the procedure parameters. Here is an example of pre/post update images with an identifier column(id). A pair of a delete row and an insert row with the same id:

    • (id=1, data='a', op='DELETE')
    • (id=1, data='b', op='INSERT')

    will be marked as pre/post update images:

    • (id=1, data='a', op='UPDATE_BEFORE')
    • (id=1, data='b', op='UPDATE_AFTER')

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected static org.apache.spark.sql.types.DataType STRING_ARRAY  
      protected static org.apache.spark.sql.types.DataType STRING_MAP  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected SparkActions actions()  
      static SparkProcedures.ProcedureBuilder builder()  
      org.apache.spark.sql.catalyst.InternalRow[] call​(org.apache.spark.sql.catalyst.InternalRow args)
      Executes this procedure.
      protected void closeService()
      Closes this procedure's executor service if a new one was created with executorService(int, String).
      java.lang.String description()
      Returns the description of this procedure.
      protected java.util.concurrent.ExecutorService executorService​(int threadPoolSize, java.lang.String nameFormat)
      Starts a new executor service which can be used by this procedure in its work.
      protected org.apache.spark.sql.Dataset<org.apache.spark.sql.Row> loadRows​(org.apache.spark.sql.connector.catalog.Identifier tableIdent, java.util.Map<java.lang.String,​java.lang.String> options)  
      protected SparkTable loadSparkTable​(org.apache.spark.sql.connector.catalog.Identifier ident)  
      protected <T> T modifyIcebergTable​(org.apache.spark.sql.connector.catalog.Identifier ident, java.util.function.Function<Table,​T> func)  
      protected org.apache.spark.sql.catalyst.InternalRow newInternalRow​(java.lang.Object... values)  
      org.apache.spark.sql.types.StructType outputType()
      Returns the type of rows produced by this procedure.
      ProcedureParameter[] parameters()
      Returns the input parameters of this procedure.
      protected void refreshSparkCache​(org.apache.spark.sql.connector.catalog.Identifier ident, org.apache.spark.sql.connector.catalog.Table table)  
      protected org.apache.spark.sql.SparkSession spark()  
      protected org.apache.spark.sql.connector.catalog.TableCatalog tableCatalog()  
      protected Spark3Util.CatalogAndIdentifier toCatalogAndIdentifier​(java.lang.String identifierAsString, java.lang.String argName, org.apache.spark.sql.connector.catalog.CatalogPlugin catalog)  
      protected org.apache.spark.sql.connector.catalog.Identifier toIdentifier​(java.lang.String identifierAsString, java.lang.String argName)  
      protected <T> T withIcebergTable​(org.apache.spark.sql.connector.catalog.Identifier ident, java.util.function.Function<Table,​T> func)  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • STRING_MAP

        protected static final org.apache.spark.sql.types.DataType STRING_MAP

      • STRING_ARRAY

        protected static final org.apache.spark.sql.types.DataType STRING_ARRAY

    • Method Detail

      • parameters

        public ProcedureParameter[] parameters()
        Description copied from interface: Procedure
        Returns the input parameters of this procedure.

      • outputType

        public org.apache.spark.sql.types.StructType outputType()
        Description copied from interface: Procedure
        Returns the type of rows produced by this procedure.

      • call

        public org.apache.spark.sql.catalyst.InternalRow[] call​(org.apache.spark.sql.catalyst.InternalRow args)
        Description copied from interface: Procedure
        Executes this procedure.

        Spark will align the provided arguments according to the input parameters defined in Procedure.parameters() either by position or by name before execution.

        Implementations may provide a summary of execution by returning one or many rows as a result. The schema of output rows must match the defined output type in Procedure.outputType().

        Parameters:
        args - input arguments
        Returns:
        the result of executing this procedure with the given arguments

      • description

        public java.lang.String description()
        Description copied from interface: Procedure
        Returns the description of this procedure.

      • spark

        protected org.apache.spark.sql.SparkSession spark()

      • tableCatalog

        protected org.apache.spark.sql.connector.catalog.TableCatalog tableCatalog()

      • modifyIcebergTable

        protected <T> T modifyIcebergTable​(org.apache.spark.sql.connector.catalog.Identifier ident,
                                   java.util.function.Function<Table,​T> func)

      • withIcebergTable

        protected <T> T withIcebergTable​(org.apache.spark.sql.connector.catalog.Identifier ident,
                                 java.util.function.Function<Table,​T> func)

      • toIdentifier

        protected org.apache.spark.sql.connector.catalog.Identifier toIdentifier​(java.lang.String identifierAsString,
                                                                         java.lang.String argName)

      • toCatalogAndIdentifier

        protected Spark3Util.CatalogAndIdentifier toCatalogAndIdentifier​(java.lang.String identifierAsString,
                                                                 java.lang.String argName,
                                                                 org.apache.spark.sql.connector.catalog.CatalogPlugin catalog)

      • loadSparkTable

        protected SparkTable loadSparkTable​(org.apache.spark.sql.connector.catalog.Identifier ident)

      • loadRows

        protected org.apache.spark.sql.Dataset<org.apache.spark.sql.Row> loadRows​(org.apache.spark.sql.connector.catalog.Identifier tableIdent,
                                                                          java.util.Map<java.lang.String,​java.lang.String> options)

      • refreshSparkCache

        protected void refreshSparkCache​(org.apache.spark.sql.connector.catalog.Identifier ident,
                                 org.apache.spark.sql.connector.catalog.Table table)

      • newInternalRow

        protected org.apache.spark.sql.catalyst.InternalRow newInternalRow​(java.lang.Object... values)

      • closeService

        protected void closeService()
        Closes this procedure's executor service if a new one was created with executorService(int, String). Does not block for any remaining tasks.

      • executorService

        protected java.util.concurrent.ExecutorService executorService​(int threadPoolSize,
                                                               java.lang.String nameFormat)
        Starts a new executor service which can be used by this procedure in its work. The pool will be automatically shut down if withIcebergTable(Identifier, Function) or modifyIcebergTable(Identifier, Function) are called. If these methods are not used then the service can be shut down with closeService() or left to be closed when this class is finalized.
        Parameters:
        threadPoolSize - number of threads in the service
        nameFormat - name prefix for threads created in this service
        Returns:
        the new executor service owned by this procedure