thrift

Type Members

1. class DailySuffixParquetThrift[T <: ThriftBase] extends DailySuffixSource with ParquetThrift[T]

   

   When Using these sources or creating subclasses of them, you can provide a filter predicate and / or a set of fields (columns) to keep (project).

   When Using these sources or creating subclasses of them, you can provide a filter predicate and / or a set of fields (columns) to keep (project).

   The filter predicate will be pushed down to the input format, potentially making the filter significantly more efficient than a filter applied to a TypedPipe (parquet push-down filters can skip reading entire chunks of data off disk).

   For data with a large schema (many fields / columns), providing the set of columns you intend to use can also make your job significantly more efficient (parquet column projection push-down will skip reading unused columns from disk). The columns are specified in the format described here: https://github.com/apache/parquet-mr/blob/master/parquet_cascading.md#21-projection-pushdown-with-thriftscrooge-records

   These settings are defined in the traits com.twitter.scalding.parquet.HasFilterPredicate and com.twitter.scalding.parquet.HasColumnProjection

   Here are two ways you can use these in a parquet source:

   class MyParquetSource(dr: DateRange) extends DailySuffixParquetThrift("/a/path", dr)
   
   val mySourceFilteredAndProjected = new MyParquetSource(dr) {
     override val withFilter: Option[FilterPredicate] = Some(myFp)
     override val withColumnProjections: Set[String] = Set("a.b.c", "x.y")
   }

   The other way is to add these as constructor arguments:

   class MyParquetSource(
     dr: DateRange,
     override val withFilter: Option[FilterPredicate] = None
     override val withColumnProjections: Set[String] = Set()
   ) extends DailySuffixParquetThrift("/a/path", dr)
   
   val mySourceFilteredAndProjected = new MyParquetSource(dr, Some(myFp), Set("a.b.c", "x.y"))

2. class FixedPathParquetThrift[T <: ThriftBase] extends FixedPathSource with ParquetThrift[T]

   

3. class HourlySuffixParquetThrift[T <: ThriftBase] extends HourlySuffixSource with ParquetThrift[T]

   

4. type Parquet346TBaseScheme[T <: TBase[_, _]] = cascading.thrift.Parquet346TBaseScheme[T]

   

5. trait ParquetThrift[T <: ThriftBase] extends FileSource with ParquetThriftBase[T]

   

6. trait ParquetThriftBase[T] extends FileSource with SingleMappable[T] with TypedSink[T] with LocalTapSource with HasFilterPredicate with HasColumnProjection