com.actian.dataflow.operators.io.parquet

Class ReadParquet

java.lang.Object

com.pervasive.datarush.operators.AbstractLogicalOperator

com.pervasive.datarush.operators.CompositeOperator

com.pervasive.datarush.operators.io.AbstractReader

com.actian.dataflow.operators.io.parquet.ReadParquet

All Implemented Interfaces:

LogicalOperator, RecordSourceOperator, SourceOperator<RecordPort>

public class ReadParquet
extends AbstractReader

Reads data previously written using Apache Parquet format by Apache Hive.

Parquet is a columnar file format used to store the tabular form of data. Parquet supports very efficient compression and encoding schemes and it allows compression schemes to be specified on per-column level. Parquet supports Compression Codecs like SNAPPY, GZIP, LZO. As Parquet is a representation of data in columnar format, it is supported by open source projects like Apache Hadoop ( MapReduce ), Apache Hive, Impala, etc;

DataFlow will automatically determine the equivalent data types from Parquet. The result will be the output type of the reader. However, as Parquet and DataFlow support different data types, not all data in Parquet format can be read. If attempting to read data which cannot be represented in DataFlow, an error will be raised.

Primitive Parquet types are mapped to DataFlow as indicated in the table below.

Parquet Type	DataFlow Type
BOOLEAN	BOOLEAN
DOUBLE	DOUBLE
FLOAT	FLOAT
INT32	INT
INT64	LONG
BINARY	STRING

Complex Parquet data types are not supported as of now.

Field Summary

Fields inherited from class com.pervasive.datarush.operators.io.AbstractReader

options, output

Constructor Summary

Constructors

Constructor and Description
ReadParquet() Reads an empty source with default settings.
ReadParquet(ByteSource source) Reads the specified data source using default options.
ReadParquet(Path path) Reads the file specified by the path.
ReadParquet(String pattern) Reads all paths matching the specified pattern using default options.

Method Summary

Modifier and Type	Method and Description
protected DataFormat	computeFormat(CompositionContext ctx) Determines the data format for the source.
ParquetMetadata	discoverMetadata(FileClient client) Gets the metadata for the currently configured data source.

Methods inherited from class com.pervasive.datarush.operators.io.AbstractReader

compose, getExtraFieldAction, getFieldErrorAction, getFieldLengthThreshold, getIncludeSourceInfo, getMissingFieldAction, getOutput, getParseOptions, getPessimisticSplitting, getReadBuffer, getReadOnClient, getRecordWarningThreshold, getSelectedFields, getSource, getSplitOptions, getUseMetadata, setExtraFieldAction, setFieldErrorAction, setFieldLengthThreshold, setIncludeSourceInfo, setMissingFieldAction, setParseErrorAction, setParseOptions, setPessimisticSplitting, setReadBuffer, setReadOnClient, setRecordWarningThreshold, setSelectedFields, setSelectedFields, setSource, setSource, setSource, setSplitOptions, setUseMetadata

Methods inherited from class com.pervasive.datarush.operators.AbstractLogicalOperator

disableParallelism, getInputPorts, getOutputPorts, newInput, newInput, newOutput, newRecordInput, newRecordInput, newRecordOutput, notifyError

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.pervasive.datarush.operators.LogicalOperator

disableParallelism, getInputPorts, getOutputPorts

Constructor Detail

ReadParquet

public ReadParquet()

Reads an empty source with default settings. The source must be set before execution or an error will be raised.

See Also:

AbstractReader.setSource(ByteSource)

ReadParquet

public ReadParquet(String pattern)

Reads all paths matching the specified pattern using default options. Any matching path which is a directory is replaced with all files in the directory; this expansion is not recursive.

Parameters:

pattern - a path-matching pattern

See Also:

FileClient.matchPaths(String)

ReadParquet

public ReadParquet(Path path)

Reads the file specified by the path. If the path refers to a directory, all files in the directory are read; this read is not recursive into sub-directories.

Parameters:

path - the path to read

ReadParquet

public ReadParquet(ByteSource source)

Reads the specified data source using default options.

Parameters:

source - the data source to read

Method Detail

computeFormat

protected DataFormat computeFormat(CompositionContext ctx)

Description copied from class: AbstractReader

Determines the data format for the source. The returned format is used during composition to construct a ReadSource operator. If an implementation supports schema discovery, it must be performed in this method.

Specified by:

computeFormat in class AbstractReader

Parameters:

ctx - the composition context for the current invocation of AbstractReader.compose(CompositionContext)

Returns:

the source format to use

discoverMetadata

public ParquetMetadata discoverMetadata(FileClient client)

Gets the metadata for the currently configured data source.

Parameters:

client - the file client

Returns:

the metadata of the source