class DataFrameReader extends Logging
Interface used to load a Dataset from external storage systems (e.g. file systems,
key-value stores, etc). Use SparkSession.read
to access this.
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- Since
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def
csv(paths: String*): DataFrame
Loads CSV files and returns the result as a
DataFrame
.Loads CSV files and returns the result as a
DataFrame
.This function will go through the input once to determine the input schema if
inferSchema
is enabled. To avoid going through the entire data once, disableinferSchema
option or specify the schema explicitly usingschema
.You can set the following CSV-specific options to deal with CSV files:
sep
(default,
): sets a single character as a separator for each field and value.encoding
(defaultUTF-8
): decodes the CSV files by the given encoding type.quote
(default"
): sets a single character used for escaping quoted values where the separator can be part of the value. If you would like to turn off quotations, you need to set notnull
but an empty string. This behaviour is different fromcom.databricks.spark.csv
.escape
(default\
): sets a single character used for escaping quotes inside an already quoted value.charToEscapeQuoteEscaping
(defaultescape
or\0
): sets a single character used for escaping the escape for the quote character. The default value is escape character when escape and quote characters are different,\0
otherwise.comment
(default empty string): sets a single character used for skipping lines beginning with this character. By default, it is disabled.header
(defaultfalse
): uses the first line as names of columns.enforceSchema
(defaulttrue
): If it is set totrue
, the specified or inferred schema will be forcibly applied to datasource files, and headers in CSV files will be ignored. If the option is set tofalse
, the schema will be validated against all headers in CSV files in the case when theheader
option is set totrue
. Field names in the schema and column names in CSV headers are checked by their positions taking into accountspark.sql.caseSensitive
. Though the default value is true, it is recommended to disable theenforceSchema
option to avoid incorrect results.inferSchema
(defaultfalse
): infers the input schema automatically from data. It requires one extra pass over the data.samplingRatio
(default is 1.0): defines fraction of rows used for schema inferring.ignoreLeadingWhiteSpace
(defaultfalse
): a flag indicating whether or not leading whitespaces from values being read should be skipped.ignoreTrailingWhiteSpace
(defaultfalse
): a flag indicating whether or not trailing whitespaces from values being read should be skipped.nullValue
(default empty string): sets the string representation of a null value. Since 2.0.1, this applies to all supported types including the string type.emptyValue
(default empty string): sets the string representation of an empty value.nanValue
(defaultNaN
): sets the string representation of a non-number" value.positiveInf
(defaultInf
): sets the string representation of a positive infinity value.negativeInf
(default-Inf
): sets the string representation of a negative infinity value.dateFormat
(defaultyyyy-MM-dd
): sets the string that indicates a date format. Custom date formats follow the formats atjava.text.SimpleDateFormat
. This applies to date type.timestampFormat
(defaultyyyy-MM-dd'T'HH:mm:ss.SSSXXX
): sets the string that indicates a timestamp format. Custom date formats follow the formats atjava.text.SimpleDateFormat
. This applies to timestamp type.maxColumns
(default20480
): defines a hard limit of how many columns a record can have.maxCharsPerColumn
(default-1
): defines the maximum number of characters allowed for any given value being read. By default, it is -1 meaning unlimited lengthmode
(defaultPERMISSIVE
): allows a mode for dealing with corrupt records during parsing. It supports the following case-insensitive modes.PERMISSIVE
: when it meets a corrupted record, puts the malformed string into a field configured bycolumnNameOfCorruptRecord
, and sets other fields tonull
. To keep corrupt records, an user can set a string type field namedcolumnNameOfCorruptRecord
in an user-defined schema. If a schema does not have the field, it drops corrupt records during parsing. A record with less/more tokens than schema is not a corrupted record to CSV. When it meets a record having fewer tokens than the length of the schema, setsnull
to extra fields. When the record has more tokens than the length of the schema, it drops extra tokens.DROPMALFORMED
: ignores the whole corrupted records.FAILFAST
: throws an exception when it meets corrupted records.columnNameOfCorruptRecord
(default is the value specified inspark.sql.columnNameOfCorruptRecord
): allows renaming the new field having malformed string created byPERMISSIVE
mode. This overridesspark.sql.columnNameOfCorruptRecord
.multiLine
(defaultfalse
): parse one record, which may span multiple lines.locale
(default isen-US
): sets a locale as language tag in IETF BCP 47 format. For instance, this is used while parsing dates and timestamps.lineSep
(default covers all\r
,\r\n
and\n
): defines the line separator that should be used for parsing. Maximum length is 1 character.
- Annotations
- @varargs()
- Since
2.0.0
-
def
csv(csvDataset: Dataset[String]): DataFrame
Loads an
Dataset[String]
storing CSV rows and returns the result as aDataFrame
.Loads an
Dataset[String]
storing CSV rows and returns the result as aDataFrame
.If the schema is not specified using
schema
function andinferSchema
option is enabled, this function goes through the input once to determine the input schema.If the schema is not specified using
schema
function andinferSchema
option is disabled, it determines the columns as string types and it reads only the first line to determine the names and the number of fields.If the enforceSchema is set to
false
, only the CSV header in the first line is checked to conform specified or inferred schema.- csvDataset
input Dataset with one CSV row per record
- Since
2.2.0
-
def
csv(path: String): DataFrame
Loads a CSV file and returns the result as a
DataFrame
.Loads a CSV file and returns the result as a
DataFrame
. See the documentation on the other overloadedcsv()
method for more details.- Since
2.0.0
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def
format(source: String): DataFrameReader
Specifies the input data source format.
Specifies the input data source format.
- Since
1.4.0
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def
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def
jdbc(url: String, table: String, predicates: Array[String], connectionProperties: Properties): DataFrame
Construct a
DataFrame
representing the database table accessible via JDBC URL url named table using connection properties.Construct a
DataFrame
representing the database table accessible via JDBC URL url named table using connection properties. Thepredicates
parameter gives a list expressions suitable for inclusion in WHERE clauses; each one defines one partition of theDataFrame
.Don't create too many partitions in parallel on a large cluster; otherwise Spark might crash your external database systems.
- 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. "fetchsize" can be used to control the number of rows per fetch.
- Since
1.4.0
-
def
jdbc(url: String, table: String, columnName: String, lowerBound: Long, upperBound: Long, numPartitions: Int, connectionProperties: Properties): DataFrame
Construct a
DataFrame
representing the database table accessible via JDBC URL url named table.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.
- 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. This, along with
lowerBound
(inclusive),upperBound
(exclusive), form partition strides for generated WHERE clause expressions used to split the columncolumnName
evenly. When the input is less than 1, the number is set to 1.- connectionProperties
JDBC database connection arguments, a list of arbitrary string tag/value. Normally at least a "user" and "password" property should be included. "fetchsize" can be used to control the number of rows per fetch and "queryTimeout" can be used to wait for a Statement object to execute to the given number of seconds.
- Since
1.4.0
-
def
jdbc(url: String, table: String, properties: Properties): DataFrame
Construct a
DataFrame
representing the database table accessible via JDBC URL url named table and connection properties.Construct a
DataFrame
representing the database table accessible via JDBC URL url named table and connection properties.- Since
1.4.0
-
def
json(jsonDataset: Dataset[String]): DataFrame
Loads a
Dataset[String]
storing JSON objects (JSON Lines text format or newline-delimited JSON) and returns the result as aDataFrame
.Loads a
Dataset[String]
storing JSON objects (JSON Lines text format or newline-delimited JSON) and returns the result as aDataFrame
.Unless the schema is specified using
schema
function, this function goes through the input once to determine the input schema.- jsonDataset
input Dataset with one JSON object per record
- Since
2.2.0
-
def
json(paths: String*): DataFrame
Loads JSON files and returns the results as a
DataFrame
.Loads JSON files and returns the results as a
DataFrame
.JSON Lines (newline-delimited JSON) is supported by default. For JSON (one record per file), set the
multiLine
option to true.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.
You can set the following JSON-specific options to deal with non-standard JSON files:
primitivesAsString
(defaultfalse
): infers all primitive values as a string typeprefersDecimal
(defaultfalse
): infers all floating-point values as a decimal type. If the values do not fit in decimal, then it infers them as doubles.allowComments
(defaultfalse
): ignores Java/C++ style comment in JSON recordsallowUnquotedFieldNames
(defaultfalse
): allows unquoted JSON field namesallowSingleQuotes
(defaulttrue
): allows single quotes in addition to double quotesallowNumericLeadingZeros
(defaultfalse
): allows leading zeros in numbers (e.g. 00012)allowBackslashEscapingAnyCharacter
(defaultfalse
): allows accepting quoting of all character using backslash quoting mechanismallowUnquotedControlChars
(defaultfalse
): allows JSON Strings to contain unquoted control characters (ASCII characters with value less than 32, including tab and line feed characters) or not.mode
(defaultPERMISSIVE
): allows a mode for dealing with corrupt records during parsing.PERMISSIVE
: when it meets a corrupted record, puts the malformed string into a field configured bycolumnNameOfCorruptRecord
, and sets other fields tonull
. To keep corrupt records, an user can set a string type field namedcolumnNameOfCorruptRecord
in an user-defined schema. If a schema does not have the field, it drops corrupt records during parsing. When inferring a schema, it implicitly adds acolumnNameOfCorruptRecord
field in an output schema.DROPMALFORMED
: ignores the whole corrupted records.FAILFAST
: throws an exception when it meets corrupted records.columnNameOfCorruptRecord
(default is the value specified inspark.sql.columnNameOfCorruptRecord
): allows renaming the new field having malformed string created byPERMISSIVE
mode. This overridesspark.sql.columnNameOfCorruptRecord
.dateFormat
(defaultyyyy-MM-dd
): sets the string that indicates a date format. Custom date formats follow the formats atjava.text.SimpleDateFormat
. This applies to date type.timestampFormat
(defaultyyyy-MM-dd'T'HH:mm:ss.SSSXXX
): sets the string that indicates a timestamp format. Custom date formats follow the formats atjava.text.SimpleDateFormat
. This applies to timestamp type.multiLine
(defaultfalse
): parse one record, which may span multiple lines, per fileencoding
(by default it is not set): allows to forcibly set one of standard basic or extended encoding for the JSON files. For example UTF-16BE, UTF-32LE. If the encoding is not specified andmultiLine
is set totrue
, it will be detected automatically.lineSep
(default covers all\r
,\r\n
and\n
): defines the line separator that should be used for parsing.samplingRatio
(default is 1.0): defines fraction of input JSON objects used for schema inferring.dropFieldIfAllNull
(defaultfalse
): whether to ignore column of all null values or empty array/struct during schema inference.locale
(default isen-US
): sets a locale as language tag in IETF BCP 47 format. For instance, this is used while parsing dates and timestamps.
- Annotations
- @varargs()
- Since
2.0.0
-
def
json(path: String): DataFrame
Loads a JSON file and returns the results as a
DataFrame
.Loads a JSON file and returns the results as a
DataFrame
.See the documentation on the overloaded
json()
method with varargs for more details.- Since
1.4.0
-
def
load(paths: String*): DataFrame
Loads input in as a
DataFrame
, for data sources that support multiple paths.Loads input in as a
DataFrame
, for data sources that support multiple paths. Only works if the source is a HadoopFsRelationProvider.- Annotations
- @varargs()
- Since
1.6.0
-
def
load(path: String): DataFrame
Loads input in as a
DataFrame
, for data sources that require a path (e.g.Loads input in as a
DataFrame
, for data sources that require a path (e.g. data backed by a local or distributed file system).- Since
1.4.0
-
def
load(): DataFrame
Loads input in as a
DataFrame
, for data sources that don't require a path (e.g.Loads input in as a
DataFrame
, for data sources that don't require a path (e.g. external key-value stores).- Since
1.4.0
-
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def
option(key: String, value: Double): DataFrameReader
Adds an input option for the underlying data source.
Adds an input option for the underlying data source.
- Since
2.0.0
-
def
option(key: String, value: Long): DataFrameReader
Adds an input option for the underlying data source.
Adds an input option for the underlying data source.
- Since
2.0.0
-
def
option(key: String, value: Boolean): DataFrameReader
Adds an input option for the underlying data source.
Adds an input option for the underlying data source.
- Since
2.0.0
-
def
option(key: String, value: String): DataFrameReader
Adds an input option for the underlying data source.
Adds an input option for the underlying data source.
You can set the following option(s):
timeZone
(default session local timezone): sets the string that indicates a timezone to be used to parse timestamps in the JSON/CSV datasources or partition values.
- Since
1.4.0
-
def
options(options: Map[String, String]): DataFrameReader
Adds input options for the underlying data source.
Adds input options for the underlying data source.
You can set the following option(s):
timeZone
(default session local timezone): sets the string that indicates a timezone to be used to parse timestamps in the JSON/CSV datasources or partition values.
- Since
1.4.0
-
def
options(options: Map[String, String]): DataFrameReader
(Scala-specific) Adds input options for the underlying data source.
(Scala-specific) Adds input options for the underlying data source.
You can set the following option(s):
timeZone
(default session local timezone): sets the string that indicates a timezone to be used to parse timestamps in the JSON/CSV datasources or partition values.
- Since
1.4.0
-
def
orc(paths: String*): DataFrame
Loads ORC files and returns the result as a
DataFrame
.Loads ORC files and returns the result as a
DataFrame
.- paths
input paths
- Annotations
- @varargs()
- Since
2.0.0
- Note
Currently, this method can only be used after enabling Hive support.
-
def
orc(path: String): DataFrame
Loads an ORC file and returns the result as a
DataFrame
.Loads an ORC file and returns the result as a
DataFrame
.- path
input path
- Since
1.5.0
- Note
Currently, this method can only be used after enabling Hive support.
-
def
parquet(paths: String*): DataFrame
Loads a Parquet file, returning the result as a
DataFrame
.Loads a Parquet file, returning the result as a
DataFrame
.You can set the following Parquet-specific option(s) for reading Parquet files:
mergeSchema
(default is the value specified inspark.sql.parquet.mergeSchema
): sets whether we should merge schemas collected from all Parquet part-files. This will overridespark.sql.parquet.mergeSchema
.
- Annotations
- @varargs()
- Since
1.4.0
-
def
parquet(path: String): DataFrame
Loads a Parquet file, returning the result as a
DataFrame
.Loads a Parquet file, returning the result as a
DataFrame
. See the documentation on the other overloadedparquet()
method for more details.- Since
2.0.0
-
def
schema(schemaString: String): DataFrameReader
Specifies the schema by using the input DDL-formatted string.
Specifies the schema by using the input DDL-formatted string. 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.
spark.read.schema("a INT, b STRING, c DOUBLE").csv("test.csv")
- Since
2.3.0
-
def
schema(schema: StructType): DataFrameReader
Specifies the input 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.
- Since
1.4.0
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
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-
def
table(tableName: String): DataFrame
Returns the specified table as a
DataFrame
.Returns the specified table as a
DataFrame
.- Since
1.4.0
-
def
text(paths: String*): DataFrame
Loads text files and returns a
DataFrame
whose schema starts with a string column named "value", and followed by partitioned columns if there are any.Loads text files and returns a
DataFrame
whose schema starts with a string column named "value", and followed by partitioned columns if there are any.By default, each line in the text files is a new row in the resulting DataFrame. For example:
// Scala: spark.read.text("/path/to/spark/README.md") // Java: spark.read().text("/path/to/spark/README.md")
You can set the following text-specific option(s) for reading text files:
wholetext
(defaultfalse
): If true, read a file as a single row and not split by "\n".lineSep
(default covers all\r
,\r\n
and\n
): defines the line separator that should be used for parsing.
- paths
input paths
- Annotations
- @varargs()
- Since
1.6.0
-
def
text(path: String): DataFrame
Loads text files and returns a
DataFrame
whose schema starts with a string column named "value", and followed by partitioned columns if there are any.Loads text files and returns a
DataFrame
whose schema starts with a string column named "value", and followed by partitioned columns if there are any. See the documentation on the other overloadedtext()
method for more details.- Since
2.0.0
-
def
textFile(paths: String*): Dataset[String]
Loads text files and returns a Dataset of String.
Loads text files and returns a Dataset of String. The underlying schema of the Dataset contains a single string column named "value".
If the directory structure of the text files contains partitioning information, those are ignored in the resulting Dataset. To include partitioning information as columns, use
text
.By default, each line in the text files is a new row in the resulting DataFrame. For example:
// Scala: spark.read.textFile("/path/to/spark/README.md") // Java: spark.read().textFile("/path/to/spark/README.md")
You can set the following textFile-specific option(s) for reading text files:
wholetext
(defaultfalse
): If true, read a file as a single row and not split by "\n".lineSep
(default covers all\r
,\r\n
and\n
): defines the line separator that should be used for parsing.
- paths
input path
- Annotations
- @varargs()
- Since
2.0.0
-
def
textFile(path: String): Dataset[String]
Loads text files and returns a Dataset of String.
Loads text files and returns a Dataset of String. See the documentation on the other overloaded
textFile()
method for more details.- Since
2.0.0
-
def
toString(): String
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Deprecated Value Members
-
def
json(jsonRDD: RDD[String]): DataFrame
Loads an
RDD[String]
storing JSON objects (JSON Lines text format or newline-delimited JSON) and returns the result as aDataFrame
.Loads an
RDD[String]
storing JSON objects (JSON Lines text format or newline-delimited JSON) and returns the result as aDataFrame
.Unless the schema is specified using
schema
function, this function goes through the input once to determine the input schema.- jsonRDD
input RDD with one JSON object per record
- Annotations
- @deprecated
- Deprecated
(Since version 2.2.0) Use json(Dataset[String]) instead.
- Since
1.4.0
-
def
json(jsonRDD: JavaRDD[String]): DataFrame
Loads a
JavaRDD[String]
storing JSON objects (JSON Lines text format or newline-delimited JSON) and returns the result as aDataFrame
.Loads a
JavaRDD[String]
storing JSON objects (JSON Lines text format or newline-delimited JSON) and returns the result as aDataFrame
.Unless the schema is specified using
schema
function, this function goes through the input once to determine the input schema.- jsonRDD
input RDD with one JSON object per record
- Annotations
- @deprecated
- Deprecated
(Since version 2.2.0) Use json(Dataset[String]) instead.
- Since
1.4.0