Module datarush.library
Package com.pervasive.datarush.operators.io.textfile

Class ParseTextFields

  • All Implemented Interfaces:
    LogicalOperator, PipelineOperator<RecordPort>, RecordPipelineOperator
    public class ParseTextFields
extends AbstractExecutableRecordPipeline
    Parses input text records according to a specified text schema. Records which fail parsing on one or more fields will be emitted on a rejects output for further remediation.

    This differs in comparison to other operators such as ReadDelimitedText which do not provide a flow of rejected records. This also differs in that it processes an existing flow of text records instead of reading from a source directly, meaning an upstream operator for breaking data into individual fields is necessary. Note that ReadDelimitedText can be used to do this syntactic parsing in the delimited text case by using a text schema containing only "raw" string fields.

    The parsed output will have the type specified by the schema. Output fields will contain the result of parsing the input field of the same name according to the type information in the provided schema.

    Input fields referenced in the schema must either be string typed, in which case they are parsed according to the schema, or be of a type assignable to the output field type, in which case they are simply passed through. If a field is present in the schema, but not in the input, the output field is NULL. If an input value is NULL, the resulting output field is NULL.

    The reject output has the same type as the input.

    • Constructor Detail

      • ParseTextFields

        public ParseTextFields()
        Defines a parser which does no parsing. Input is copied directly to the output.

      • ParseTextFields

        public ParseTextFields​(RecordTextSchema<?> schema)
        Defines a parser using the specified schema. Output records will have this schema. Any schema fields not present in the input will be NULL in the output.
        Parameters:
        schema - the record schema for parsing

    • Method Detail

      • getRejects

        public RecordPort getRejects()
        Gets the port providing records which failed parsing.
        Returns:
        all records for which one or more fields failed to parse.

      • getSchema

        public RecordTextSchema<?> getSchema()
        Gets the record schema to use for parsing.
        Returns:
        the record schema for parsing

      • setSchema

        public void setSchema​(RecordTextSchema<?> schema)
        Sets the record schema to use for parsing. Output records will have this schema.

        Input fields referenced in the schema must either be string typed, in which case they are parsed according to the schema, or be of a type assignable to the output field type, in which case they are simply passed through. Any schema fields not present in the input will be NULL in the output.

        Parameters:
        schema - the record schema for parsing

      • computeMetadata

        protected void computeMetadata​(StreamingMetadataContext ctx)
        Description copied from class: StreamingOperator
        Implementations must adhere to the following contracts

        General

        Regardless of input ports/output port types, all implementations must do the following:

        1. Validation. Validation of configuration should always be performed first.
        2. Declare parallelizability.. Implementations must declare parallelizability by calling StreamingMetadataContext.parallelize(ParallelismStrategy).

        Input record ports

        Implementations with input record ports must declare the following:
        1. Required data ordering:
          2. Implementations that have data ordering requirements must declare them by calling RecordPort#setRequiredDataOrdering, otherwise data may arrive in any order.
        2. Required data distribution (only applies to parallelizable operators):
          3. Implementations that have data distribution requirements must declare them by calling RecordPort#setRequiredDataDistribution, otherwise data will arrive in an unspecified partial distribution.
        Note that if the upstream operator's output distribution/ordering is compatible with those required, we avoid a re-sort/re-distribution which is generally a very large savings from a performance standpoint. In addition, some operators may chose to query the upstream output distribution/ordering by calling RecordPort#getSourceDataDistribution and RecordPort#getSourceDataOrdering. These should be viewed as a hints to help chose a more efficient algorithm. In such cases, though, operators must still declare data ordering and data distribution requirements; otherwise there is no guarantee that data will arrive sorted/distributed as required.

        Output record ports

        Implementations with output record ports must declare the following:
        1. Type: Implementations must declare their output type by calling RecordPort#setType.
        Implementations with output record ports may declare the following:
        1. Output data ordering: Implementations that can make guarantees as to their output ordering may do so by calling RecordPort#setOutputDataOrdering
        2. Output data distribution (only applies to parallelizable operators): Implementations that can make guarantees as to their output distribution may do so by calling RecordPort#setOutputDataDistribution
        Note that both of these properties are optional; if unspecified, performance may suffer since the framework may unnecessarily re-sort/re-distributed the data.

        Input model ports

        In general, there is nothing special to declare for input model ports. Models are implicitly duplicated to all partitions when going from non-parallel to parallel operators. The case of a model going from a parallel to a non-parallel node is a special case of a "model reducer" operator. In the case of a model reducer, the downstream operator, must declare the following:
        1. Merge handler: Model reducers must declare a merge handler by calling AbstractModelPort#setMergeHandler.
        Note that MergeModel is a convenient, re-usable model reducer, parameterized with a merge-handler.

        Output model ports

        SimpleModelPort's have no associated metadata and therefore there is never any output metadata to declare. PMMLPort's, on the other hand, do have associated metadata. For all PMMLPorts, implementations must declare the following:
        1. pmmlModelSpec: Implementations must declare the PMML model spec by calling PMMLPort.setPMMLModelSpec.
        Specified by:
        computeMetadata in class StreamingOperator
        Parameters:
        ctx - the context

      • execute

        protected void execute​(ExecutionContext ctx)
        Description copied from class: ExecutableOperator
        Executes the operator. Implementations should adhere to the following contracts:
        1. Following execution, all input ports must be at end-of-data.
        2. Following execution, all output ports must be at end-of-data.
        Specified by:
        execute in class ExecutableOperator
        Parameters:
        ctx - context in which to lookup physical ports bound to logical ports