trait MapGroupCompiler[T] extends InputLayers with InputOptPartitioner with CompileInFn[T] with OutputLayers with OutputOptPartitioner with CompileOutFn[T]
Compiler to implement a generic Map-Reduce pattern, where the reduce function is group-by. The front-end compiler each input partition and produces the list of output partition that this input affect, each with a value of custom type. Values are then grouped per output partition and passed to the back-end that produces the output map.
This pattern is a more general version of Direct1ToNCompiler and DirectMToNCompiler where not only a M:N input/output relationship is supported, but this relationship is function of the input payloads, so the input content.
This pattern, however, compiles input partitions standalone, meaning that compiling one input partition sees data and metadata of that partition only. In case it is needed to lookup information from additional input partition in the front-end, please refer to RefTreeCompiler.
- T
the custom type of the values passed between front-end and back-end
- Note
the implementation must be scala.Serializable as this is copied to workers and run inside Spark map functions
- See also
traits mixed in for more details
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- MapGroupCompiler
- CompileOutFn
- OutputOptPartitioner
- OutputLayers
- CompileInFn
- Serializable
- Serializable
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abstract
def
compileInFn(in: (InKey, InMeta)): Iterable[(OutKey, T)]
Calculates the dependent output partitions and intermediate results from a single input partition.
Calculates the dependent output partitions and intermediate results from a single input partition.
- in
the input partition to process
- returns
all the impacted output partitions com.here.platform.data.processing.compiler.OutKey and intermediate data of type
Tfor this partition. It may contain more than one element per output key. compileOutFn will only be called for outKeys which have at least one intermediate value from this phase. Other outKeys will be automatically deleted.
- Definition Classes
- CompileInFn
-
abstract
def
compileOutFnDefined(): Unit
Must be overridden as final by all subclasses, to block the mixin of different interfaces in the same compiler class and to assure that at least one child interface is mixed in.
Must be overridden as final by all subclasses, to block the mixin of different interfaces in the same compiler class and to assure that at least one child interface is mixed in.
- Attributes
- protected
- Definition Classes
- CompileOutFn
-
abstract
def
inLayers: Map[Id, Set[Id]]
Represents layers of the input catalogs that you should query and provide to the compiler.
Represents layers of the input catalogs that you should query and provide to the compiler. These layers are grouped by input catalog and identified by catalog ID and layer ID.
- Definition Classes
- InputLayers
-
abstract
def
inPartitioner(parallelism: Int): Option[Partitioner[InKey]]
Specifies the partitioner to use when querying the input catalogs.
Specifies the partitioner to use when querying the input catalogs. If no partitioner is provided, by returning None from this function, then the Executor uses the default partitioner.
- parallelism
The number of partitions the partitioner should partition the catalog into, this should match the parallelism of the Spark RDD containing the input partitions.
- returns
The optional input partitioner with the parallelism specified.
- Definition Classes
- InputOptPartitioner
-
abstract
def
outLayers: Set[Id]
Layers to be produced by the compiler.
Layers to be produced by the compiler.
- Definition Classes
- OutputLayers
-
abstract
def
outPartitioner(parallelism: Int): Option[Partitioner[OutKey]]
Specifies the partitioner to use when querying the output catalog and producing output data.
Specifies the partitioner to use when querying the output catalog and producing output data. If no partitioner is provided, by returning None from this function, then the Executor uses the default partitioner.
- parallelism
The number of partitions the partitioner should partition the catalog into, this should match the parallelism of the Spark RDD containing the output partitions.
- returns
The optional output partitioner with the parallelism specified.
- Definition Classes
- OutputOptPartitioner
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val
outCatalogId: Id
Identifier for the output catalog.
Identifier for the output catalog.
- Definition Classes
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