org.apache.spark.sql
Class DataFrameReader

Object
  org.apache.spark.sql.DataFrameReader

public class DataFrameReader
extends Object

:: Experimental :: Interface used to load a DataFrame from external storage systems (e.g. file systems, key-value stores, etc). Use SQLContext.read to access this.

Since:

1.4.0

Method Summary

DataFrameReader	format(String source) Specifies the input data source format.
DataFrame	jdbc(String url, String table, java.util.Properties properties) Construct a DataFrame representing the database table accessible via JDBC URL url named table and connection properties.
DataFrame	jdbc(String url, String table, String[] predicates, java.util.Properties connectionProperties) Construct a DataFrame representing the database table accessible via JDBC URL url named table using connection properties.
DataFrame	jdbc(String url, String table, String columnName, long lowerBound, long upperBound, int numPartitions, java.util.Properties connectionProperties) Construct a DataFrame representing the database table accessible via JDBC URL url named table.
DataFrame	json(JavaRDD<String> jsonRDD) Loads an JavaRDD[String] storing JSON objects (one object per record) and returns the result as a DataFrame.
DataFrame	json(RDD<String> jsonRDD) Loads an RDD[String] storing JSON objects (one object per record) and returns the result as a DataFrame.
DataFrame	json(String path) Loads a JSON file (one object per line) and returns the result as a DataFrame.
DataFrame	load() Loads input in as a DataFrame, for data sources that don't require a path (e.g.
DataFrame	load(String path) Loads input in as a DataFrame, for data sources that require a path (e.g.
DataFrameReader	option(String key, String value) Adds an input option for the underlying data source.
DataFrameReader	options(scala.collection.Map<String,String> options) (Scala-specific) Adds input options for the underlying data source.
DataFrameReader	options(java.util.Map<String,String> options) Adds input options for the underlying data source.
DataFrame	parquet(scala.collection.Seq<String> paths) Loads a Parquet file, returning the result as a DataFrame.
DataFrame	parquet(String... paths) Loads a Parquet file, returning the result as a DataFrame.
DataFrameReader	schema(StructType schema) Specifies the input schema.
DataFrame	table(String tableName) Returns the specified table as a DataFrame.

Methods inherited from class Object

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

Method Detail

parquet

public DataFrame parquet(String... paths)

Loads a Parquet file, returning the result as a DataFrame. This function returns an empty DataFrame if no paths are passed in.

Parameters:

paths - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

format

public DataFrameReader format(String source)

Specifies the input data source format.

Parameters:

source - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

schema

public DataFrameReader schema(StructType schema)

Specifies the input schema. Some data sources (e.g. JSON) can infer the input schema automatically from data. By specifying the schema here, the underlying data source can skip the schema inference step, and thus speed up data loading.

Parameters:

schema - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

option

public DataFrameReader option(String key,
                              String value)

Adds an input option for the underlying data source.

Parameters:

key - (undocumented)

value - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

options

public DataFrameReader options(scala.collection.Map<String,String> options)

(Scala-specific) Adds input options for the underlying data source.

Parameters:

options - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

options

public DataFrameReader options(java.util.Map<String,String> options)

Adds input options for the underlying data source.

Parameters:

options - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

load

public DataFrame load(String path)

Loads input in as a DataFrame, for data sources that require a path (e.g. data backed by a local or distributed file system).

Parameters:

path - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

load

public DataFrame load()

Loads input in as a DataFrame, for data sources that don't require a path (e.g. external key-value stores).

Returns:

(undocumented)

Since:

1.4.0

jdbc

public DataFrame jdbc(String url,
                      String table,
                      java.util.Properties properties)

Construct a DataFrame representing the database table accessible via JDBC URL url named table and connection properties.

Parameters:

url - (undocumented)

table - (undocumented)

properties - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

jdbc

public DataFrame jdbc(String url,
                      String table,
                      String columnName,
                      long lowerBound,
                      long upperBound,
                      int numPartitions,
                      java.util.Properties connectionProperties)

Construct a DataFrame representing the database table accessible via JDBC URL url named table. Partitions of the table will be retrieved in parallel based on the parameters passed to this function.

Don't create too many partitions in parallel on a large cluster; otherwise Spark might crash your external database systems.

Parameters:

url - JDBC database url of the form jdbc:subprotocol:subname

table - Name of the table in the external database.

columnName - the name of a column of integral type that will be used for partitioning.

lowerBound - the minimum value of columnName used to decide partition stride

upperBound - the maximum value of columnName used to decide partition stride

numPartitions - the number of partitions. the range minValue-maxValue will be split evenly into this many partitions

connectionProperties - JDBC database connection arguments, a list of arbitrary string tag/value. Normally at least a "user" and "password" property should be included.

Returns:

(undocumented)

Since:

1.4.0

jdbc

public DataFrame jdbc(String url,
                      String table,
                      String[] predicates,
                      java.util.Properties connectionProperties)

Construct a DataFrame representing the database table accessible via JDBC URL url named table using connection properties. The predicates parameter gives a list expressions suitable for inclusion in WHERE clauses; each one defines one partition of the DataFrame.

Don't create too many partitions in parallel on a large cluster; otherwise Spark might crash your external database systems.

Parameters:

url - JDBC database url of the form jdbc:subprotocol:subname

table - Name of the table in the external database.

predicates - Condition in the where clause for each partition.

connectionProperties - JDBC database connection arguments, a list of arbitrary string tag/value. Normally at least a "user" and "password" property should be included.

Returns:

(undocumented)

Since:

1.4.0

json

public DataFrame json(String path)

Loads a JSON file (one object per line) and returns the result as a DataFrame.

This function goes through the input once to determine the input schema. If you know the schema in advance, use the version that specifies the schema to avoid the extra scan.

Parameters:

path - input path

Returns:

(undocumented)

Since:

1.4.0

json

public DataFrame json(JavaRDD<String> jsonRDD)

Loads an JavaRDD[String] storing JSON objects (one object per record) and returns the result as a DataFrame.

Unless the schema is specified using schema function, this function goes through the input once to determine the input schema.

Parameters:

jsonRDD - input RDD with one JSON object per record

Returns:

(undocumented)

Since:

1.4.0

json

public DataFrame json(RDD<String> jsonRDD)

Loads an RDD[String] storing JSON objects (one object per record) and returns the result as a DataFrame.

Unless the schema is specified using schema function, this function goes through the input once to determine the input schema.

Parameters:

jsonRDD - input RDD with one JSON object per record

Returns:

(undocumented)

Since:

1.4.0

parquet

public DataFrame parquet(scala.collection.Seq<String> paths)

Loads a Parquet file, returning the result as a DataFrame. This function returns an empty DataFrame if no paths are passed in.

Parameters:

paths - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

table

public DataFrame table(String tableName)

Returns the specified table as a DataFrame.

Parameters:

tableName - (undocumented)

Returns:

(undocumented)

Since:

1.4.0