Interface BuiltInMetadata.ColumnOrigin

    • Method Detail

      • getColumnOrigins

        java.util.Set<RelColumnOrigin> getColumnOrigins​(int outputColumn)
        For a given output column of an expression, determines all columns of underlying tables which contribute to result values. An output column may have more than one origin due to expressions such as Union and LogicalProject. The optimizer may use this information for catalog access (e.g. index availability).
        outputColumn - 0-based ordinal for output column of interest
        set of origin columns, or null if this information cannot be determined (whereas empty set indicates definitely no origin columns at all)