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streaming.py
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#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import sys
import json
from py4j.java_gateway import java_import
from pyspark import since, keyword_only
from pyspark.sql.column import _to_seq
from pyspark.sql.readwriter import OptionUtils, to_str
from pyspark.sql.types import StructType, StructField, StringType
from pyspark.sql.utils import ForeachBatchFunction, StreamingQueryException
__all__ = ["StreamingQuery", "StreamingQueryManager", "DataStreamReader", "DataStreamWriter"]
class StreamingQuery(object):
"""
A handle to a query that is executing continuously in the background as new data arrives.
All these methods are thread-safe.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
"""
def __init__(self, jsq):
self._jsq = jsq
@property
@since(2.0)
def id(self):
"""Returns the unique id of this query that persists across restarts from checkpoint data.
That is, this id is generated when a query is started for the first time, and
will be the same every time it is restarted from checkpoint data.
There can only be one query with the same id active in a Spark cluster.
Also see, `runId`.
"""
return self._jsq.id().toString()
@property
@since(2.1)
def runId(self):
"""Returns the unique id of this query that does not persist across restarts. That is, every
query that is started (or restarted from checkpoint) will have a different runId.
"""
return self._jsq.runId().toString()
@property
@since(2.0)
def name(self):
"""Returns the user-specified name of the query, or null if not specified.
This name can be specified in the `org.apache.spark.sql.streaming.DataStreamWriter`
as `dataframe.writeStream.queryName("query").start()`.
This name, if set, must be unique across all active queries.
"""
return self._jsq.name()
@property
@since(2.0)
def isActive(self):
"""Whether this streaming query is currently active or not.
"""
return self._jsq.isActive()
@since(2.0)
def awaitTermination(self, timeout=None):
"""Waits for the termination of `this` query, either by :func:`query.stop()` or by an
exception. If the query has terminated with an exception, then the exception will be thrown.
If `timeout` is set, it returns whether the query has terminated or not within the
`timeout` seconds.
If the query has terminated, then all subsequent calls to this method will either return
immediately (if the query was terminated by :func:`stop()`), or throw the exception
immediately (if the query has terminated with exception).
throws :class:`StreamingQueryException`, if `this` query has terminated with an exception
"""
if timeout is not None:
if not isinstance(timeout, (int, float)) or timeout < 0:
raise ValueError("timeout must be a positive integer or float. Got %s" % timeout)
return self._jsq.awaitTermination(int(timeout * 1000))
else:
return self._jsq.awaitTermination()
@property
@since(2.1)
def status(self):
"""
Returns the current status of the query.
"""
return json.loads(self._jsq.status().json())
@property
@since(2.1)
def recentProgress(self):
"""Returns an array of the most recent [[StreamingQueryProgress]] updates for this query.
The number of progress updates retained for each stream is configured by Spark session
configuration `spark.sql.streaming.numRecentProgressUpdates`.
"""
return [json.loads(p.json()) for p in self._jsq.recentProgress()]
@property
def lastProgress(self):
"""
Returns the most recent :class:`StreamingQueryProgress` update of this streaming query or
None if there were no progress updates
.. versionadded:: 2.1.0
Returns
-------
dict
"""
lastProgress = self._jsq.lastProgress()
if lastProgress:
return json.loads(lastProgress.json())
else:
return None
def processAllAvailable(self):
"""Blocks until all available data in the source has been processed and committed to the
sink. This method is intended for testing.
.. versionadded:: 2.0.0
Notes
-----
In the case of continually arriving data, this method may block forever.
Additionally, this method is only guaranteed to block until data that has been
synchronously appended data to a stream source prior to invocation.
(i.e. `getOffset` must immediately reflect the addition).
"""
return self._jsq.processAllAvailable()
@since(2.0)
def stop(self):
"""Stop this streaming query.
"""
self._jsq.stop()
def explain(self, extended=False):
"""Prints the (logical and physical) plans to the console for debugging purpose.
.. versionadded:: 2.1.0
Parameters
----------
extended : bool, optional
default ``False``. If ``False``, prints only the physical plan.
Examples
--------
>>> sq = sdf.writeStream.format('memory').queryName('query_explain').start()
>>> sq.processAllAvailable() # Wait a bit to generate the runtime plans.
>>> sq.explain()
== Physical Plan ==
...
>>> sq.explain(True)
== Parsed Logical Plan ==
...
== Analyzed Logical Plan ==
...
== Optimized Logical Plan ==
...
== Physical Plan ==
...
>>> sq.stop()
"""
# Cannot call `_jsq.explain(...)` because it will print in the JVM process.
# We should print it in the Python process.
print(self._jsq.explainInternal(extended))
def exception(self):
"""
.. versionadded:: 2.1.0
Returns
-------
:class:`StreamingQueryException`
the StreamingQueryException if the query was terminated by an exception, or None.
"""
if self._jsq.exception().isDefined():
je = self._jsq.exception().get()
msg = je.toString().split(': ', 1)[1] # Drop the Java StreamingQueryException type info
stackTrace = '\n\t at '.join(map(lambda x: x.toString(), je.getStackTrace()))
return StreamingQueryException(msg, stackTrace, je.getCause())
else:
return None
class StreamingQueryManager(object):
"""A class to manage all the :class:`StreamingQuery` StreamingQueries active.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
"""
def __init__(self, jsqm):
self._jsqm = jsqm
@property
def active(self):
"""Returns a list of active queries associated with this SQLContext
.. versionadded:: 2.0.0
Examples
--------
>>> sq = sdf.writeStream.format('memory').queryName('this_query').start()
>>> sqm = spark.streams
>>> # get the list of active streaming queries
>>> [q.name for q in sqm.active]
['this_query']
>>> sq.stop()
"""
return [StreamingQuery(jsq) for jsq in self._jsqm.active()]
def get(self, id):
"""Returns an active query from this SQLContext or throws exception if an active query
with this name doesn't exist.
.. versionadded:: 2.0.0
Examples
--------
>>> sq = sdf.writeStream.format('memory').queryName('this_query').start()
>>> sq.name
'this_query'
>>> sq = spark.streams.get(sq.id)
>>> sq.isActive
True
>>> sq = sqlContext.streams.get(sq.id)
>>> sq.isActive
True
>>> sq.stop()
"""
return StreamingQuery(self._jsqm.get(id))
@since(2.0)
def awaitAnyTermination(self, timeout=None):
"""Wait until any of the queries on the associated SQLContext has terminated since the
creation of the context, or since :func:`resetTerminated()` was called. If any query was
terminated with an exception, then the exception will be thrown.
If `timeout` is set, it returns whether the query has terminated or not within the
`timeout` seconds.
If a query has terminated, then subsequent calls to :func:`awaitAnyTermination()` will
either return immediately (if the query was terminated by :func:`query.stop()`),
or throw the exception immediately (if the query was terminated with exception). Use
:func:`resetTerminated()` to clear past terminations and wait for new terminations.
In the case where multiple queries have terminated since :func:`resetTermination()`
was called, if any query has terminated with exception, then :func:`awaitAnyTermination()`
will throw any of the exception. For correctly documenting exceptions across multiple
queries, users need to stop all of them after any of them terminates with exception, and
then check the `query.exception()` for each query.
throws :class:`StreamingQueryException`, if `this` query has terminated with an exception
"""
if timeout is not None:
if not isinstance(timeout, (int, float)) or timeout < 0:
raise ValueError("timeout must be a positive integer or float. Got %s" % timeout)
return self._jsqm.awaitAnyTermination(int(timeout * 1000))
else:
return self._jsqm.awaitAnyTermination()
def resetTerminated(self):
"""Forget about past terminated queries so that :func:`awaitAnyTermination()` can be used
again to wait for new terminations.
.. versionadded:: 2.0.0
Examples
--------
>>> spark.streams.resetTerminated()
"""
self._jsqm.resetTerminated()
class DataStreamReader(OptionUtils):
"""
Interface used to load a streaming :class:`DataFrame <pyspark.sql.DataFrame>` from external
storage systems (e.g. file systems, key-value stores, etc).
Use :attr:`SparkSession.readStream <pyspark.sql.SparkSession.readStream>` to access this.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
"""
def __init__(self, spark):
self._jreader = spark._ssql_ctx.readStream()
self._spark = spark
def _df(self, jdf):
from pyspark.sql.dataframe import DataFrame
return DataFrame(jdf, self._spark)
def format(self, source):
"""Specifies the input data source format.
.. versionadded:: 2.0.0
Parameters
----------
source : str
name of the data source, e.g. 'json', 'parquet'.
Notes
-----
This API is evolving.
Examples
--------
>>> s = spark.readStream.format("text")
"""
self._jreader = self._jreader.format(source)
return self
def schema(self, 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.
.. versionadded:: 2.0.0
Parameters
----------
schema : :class:`pyspark.sql.types.StructType` or str
a :class:`pyspark.sql.types.StructType` object or a DDL-formatted string
(For example ``col0 INT, col1 DOUBLE``).
Notes
-----
This API is evolving.
Examples
--------
>>> s = spark.readStream.schema(sdf_schema)
>>> s = spark.readStream.schema("col0 INT, col1 DOUBLE")
"""
from pyspark.sql import SparkSession
spark = SparkSession.builder.getOrCreate()
if isinstance(schema, StructType):
jschema = spark._jsparkSession.parseDataType(schema.json())
self._jreader = self._jreader.schema(jschema)
elif isinstance(schema, str):
self._jreader = self._jreader.schema(schema)
else:
raise TypeError("schema should be StructType or string")
return self
def option(self, key, value):
"""Adds an input option for the underlying data source.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
Examples
--------
>>> s = spark.readStream.option("x", 1)
"""
self._jreader = self._jreader.option(key, to_str(value))
return self
def options(self, **options):
"""Adds input options for the underlying data source.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
Examples
--------
>>> s = spark.readStream.options(x="1", y=2)
"""
for k in options:
self._jreader = self._jreader.option(k, to_str(options[k]))
return self
def load(self, path=None, format=None, schema=None, **options):
"""Loads a data stream from a data source and returns it as a
:class:`DataFrame <pyspark.sql.DataFrame>`.
.. versionadded:: 2.0.0
Parameters
----------
path : str, optional
optional string for file-system backed data sources.
format : str, optional
optional string for format of the data source. Default to 'parquet'.
schema : :class:`pyspark.sql.types.StructType` or str, optional
optional :class:`pyspark.sql.types.StructType` for the input schema
or a DDL-formatted string (For example ``col0 INT, col1 DOUBLE``).
**options : dict
all other string options
Notes
-----
This API is evolving.
Examples
--------
>>> json_sdf = spark.readStream.format("json") \\
... .schema(sdf_schema) \\
... .load(tempfile.mkdtemp())
>>> json_sdf.isStreaming
True
>>> json_sdf.schema == sdf_schema
True
"""
if format is not None:
self.format(format)
if schema is not None:
self.schema(schema)
self.options(**options)
if path is not None:
if type(path) != str or len(path.strip()) == 0:
raise ValueError("If the path is provided for stream, it needs to be a " +
"non-empty string. List of paths are not supported.")
return self._df(self._jreader.load(path))
else:
return self._df(self._jreader.load())
def json(self, path, schema=None, primitivesAsString=None, prefersDecimal=None,
allowComments=None, allowUnquotedFieldNames=None, allowSingleQuotes=None,
allowNumericLeadingZero=None, allowBackslashEscapingAnyCharacter=None,
mode=None, columnNameOfCorruptRecord=None, dateFormat=None, timestampFormat=None,
multiLine=None, allowUnquotedControlChars=None, lineSep=None, locale=None,
dropFieldIfAllNull=None, encoding=None, pathGlobFilter=None,
recursiveFileLookup=None, allowNonNumericNumbers=None):
"""
Loads a JSON file stream and returns the results as a :class:`DataFrame`.
`JSON Lines <http://jsonlines.org/>`_ (newline-delimited JSON) is supported by default.
For JSON (one record per file), set the ``multiLine`` parameter to ``true``.
If the ``schema`` parameter is not specified, this function goes
through the input once to determine the input schema.
.. versionadded:: 2.0.0
Parameters
----------
path : str
string represents path to the JSON dataset,
or RDD of Strings storing JSON objects.
schema : :class:`pyspark.sql.types.StructType` or str, optional
an optional :class:`pyspark.sql.types.StructType` for the input schema
or a DDL-formatted string (For example ``col0 INT, col1 DOUBLE``).
Other Parameters
----------------
Extra options
For the extra options, refer to
`Data Source Option <https://spark.apache.org/docs/latest/sql-data-sources-json.html#data-source-option>`_ # noqa
in the version you use.
Notes
-----
This API is evolving.
Examples
--------
>>> json_sdf = spark.readStream.json(tempfile.mkdtemp(), schema = sdf_schema)
>>> json_sdf.isStreaming
True
>>> json_sdf.schema == sdf_schema
True
"""
self._set_opts(
schema=schema, primitivesAsString=primitivesAsString, prefersDecimal=prefersDecimal,
allowComments=allowComments, allowUnquotedFieldNames=allowUnquotedFieldNames,
allowSingleQuotes=allowSingleQuotes, allowNumericLeadingZero=allowNumericLeadingZero,
allowBackslashEscapingAnyCharacter=allowBackslashEscapingAnyCharacter,
mode=mode, columnNameOfCorruptRecord=columnNameOfCorruptRecord, dateFormat=dateFormat,
timestampFormat=timestampFormat, multiLine=multiLine,
allowUnquotedControlChars=allowUnquotedControlChars, lineSep=lineSep, locale=locale,
dropFieldIfAllNull=dropFieldIfAllNull, encoding=encoding,
pathGlobFilter=pathGlobFilter, recursiveFileLookup=recursiveFileLookup,
allowNonNumericNumbers=allowNonNumericNumbers)
if isinstance(path, str):
return self._df(self._jreader.json(path))
else:
raise TypeError("path can be only a single string")
def orc(self, path, mergeSchema=None, pathGlobFilter=None, recursiveFileLookup=None):
"""Loads a ORC file stream, returning the result as a :class:`DataFrame`.
.. versionadded:: 2.3.0
Other Parameters
----------------
Extra options
For the extra options, refer to
`Data Source Option <https://spark.apache.org/docs/latest/sql-data-sources-orc.html#data-source-option>`_ # noqa
in the version you use.
Examples
--------
>>> orc_sdf = spark.readStream.schema(sdf_schema).orc(tempfile.mkdtemp())
>>> orc_sdf.isStreaming
True
>>> orc_sdf.schema == sdf_schema
True
"""
self._set_opts(mergeSchema=mergeSchema, pathGlobFilter=pathGlobFilter,
recursiveFileLookup=recursiveFileLookup)
if isinstance(path, str):
return self._df(self._jreader.orc(path))
else:
raise TypeError("path can be only a single string")
def parquet(self, path, mergeSchema=None, pathGlobFilter=None, recursiveFileLookup=None,
datetimeRebaseMode=None, int96RebaseMode=None):
"""
Loads a Parquet file stream, returning the result as a :class:`DataFrame`.
.. versionadded:: 2.0.0
Parameters
----------
path : str
the path in any Hadoop supported file system
Other Parameters
----------------
Extra options
For the extra options, refer to
`Data Source Option <https://spark.apache.org/docs/latest/sql-data-sources-parquet.html#data-source-option>`_. # noqa
in the version you use.
Examples
--------
>>> parquet_sdf = spark.readStream.schema(sdf_schema).parquet(tempfile.mkdtemp())
>>> parquet_sdf.isStreaming
True
>>> parquet_sdf.schema == sdf_schema
True
"""
self._set_opts(mergeSchema=mergeSchema, pathGlobFilter=pathGlobFilter,
recursiveFileLookup=recursiveFileLookup,
datetimeRebaseMode=datetimeRebaseMode, int96RebaseMode=int96RebaseMode)
if isinstance(path, str):
return self._df(self._jreader.parquet(path))
else:
raise TypeError("path can be only a single string")
def text(self, path, wholetext=False, lineSep=None, pathGlobFilter=None,
recursiveFileLookup=None):
"""
Loads a text file stream and returns a :class:`DataFrame` whose schema starts with a
string column named "value", and followed by partitioned columns if there
are any.
The text files must be encoded as UTF-8.
By default, each line in the text file is a new row in the resulting DataFrame.
.. versionadded:: 2.0.0
Parameters
----------
paths : str or list
string, or list of strings, for input path(s).
wholetext : str or bool, optional
if true, read each file from input path(s) as a single row.
lineSep : str, optional
defines the line separator that should be used for parsing. If None is
set, it covers all ``\\r``, ``\\r\\n`` and ``\\n``.
pathGlobFilter : str or bool, optional
an optional glob pattern to only include files with paths matching
the pattern. The syntax follows `org.apache.hadoop.fs.GlobFilter`.
It does not change the behavior of `partition discovery`_.
recursiveFileLookup : str or bool, optional
recursively scan a directory for files. Using this option
disables
`partition discovery <https://spark.apache.org/docs/latest/sql-data-sources-parquet.html#partition-discovery>`_. # noqa
Notes
-----
This API is evolving.
Examples
--------
>>> text_sdf = spark.readStream.text(tempfile.mkdtemp())
>>> text_sdf.isStreaming
True
>>> "value" in str(text_sdf.schema)
True
"""
self._set_opts(
wholetext=wholetext, lineSep=lineSep, pathGlobFilter=pathGlobFilter,
recursiveFileLookup=recursiveFileLookup)
if isinstance(path, str):
return self._df(self._jreader.text(path))
else:
raise TypeError("path can be only a single string")
def csv(self, path, schema=None, sep=None, encoding=None, quote=None, escape=None,
comment=None, header=None, inferSchema=None, ignoreLeadingWhiteSpace=None,
ignoreTrailingWhiteSpace=None, nullValue=None, nanValue=None, positiveInf=None,
negativeInf=None, dateFormat=None, timestampFormat=None, maxColumns=None,
maxCharsPerColumn=None, maxMalformedLogPerPartition=None, mode=None,
columnNameOfCorruptRecord=None, multiLine=None, charToEscapeQuoteEscaping=None,
enforceSchema=None, emptyValue=None, locale=None, lineSep=None,
pathGlobFilter=None, recursiveFileLookup=None, unescapedQuoteHandling=None):
r"""Loads a CSV file stream and returns the result as a :class:`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, disable
``inferSchema`` option or specify the schema explicitly using ``schema``.
Parameters
----------
path : str or list
string, or list of strings, for input path(s).
schema : :class:`pyspark.sql.types.StructType` or str, optional
an optional :class:`pyspark.sql.types.StructType` for the input schema
or a DDL-formatted string (For example ``col0 INT, col1 DOUBLE``).
sep : str, optional
sets a separator (one or more characters) for each field and value. If None is
set, it uses the default value, ``,``.
encoding : str, optional
decodes the CSV files by the given encoding type. If None is set,
it uses the default value, ``UTF-8``.
quote : str, optional sets a single character used for escaping quoted values where the
separator can be part of the value. If None is set, it uses the default
value, ``"``. If you would like to turn off quotations, you need to set an
empty string.
escape : str, optional
sets a single character used for escaping quotes inside an already
quoted value. If None is set, it uses the default value, ``\``.
comment : str, optional
sets a single character used for skipping lines beginning with this
character. By default (None), it is disabled.
header : str or bool, optional
uses the first line as names of columns. If None is set, it uses the
default value, ``false``.
inferSchema : str or bool, optional
infers the input schema automatically from data. It requires one extra
pass over the data. If None is set, it uses the default value, ``false``.
enforceSchema : str or bool, optional
If it is set to ``true``, 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 to ``false``, the schema will be
validated against all headers in CSV files or the first header in RDD
if the ``header`` option is set to ``true``. Field names in the schema
and column names in CSV headers are checked by their positions
taking into account ``spark.sql.caseSensitive``. If None is set,
``true`` is used by default. Though the default value is ``true``,
it is recommended to disable the ``enforceSchema`` option
to avoid incorrect results.
ignoreLeadingWhiteSpace : str or bool, optional
a flag indicating whether or not leading whitespaces from
values being read should be skipped. If None is set, it
uses the default value, ``false``.
ignoreTrailingWhiteSpace : str or bool, optional
a flag indicating whether or not trailing whitespaces from
values being read should be skipped. If None is set, it
uses the default value, ``false``.
nullValue : str, optional
sets the string representation of a null value. If None is set, it uses
the default value, empty string. Since 2.0.1, this ``nullValue`` param
applies to all supported types including the string type.
nanValue : str, optional
sets the string representation of a non-number value. If None is set, it
uses the default value, ``NaN``.
positiveInf : str, optional
sets the string representation of a positive infinity value. If None
is set, it uses the default value, ``Inf``.
negativeInf : str, optional
sets the string representation of a negative infinity value. If None
is set, it uses the default value, ``Inf``.
dateFormat : str, optional
sets the string that indicates a date format. Custom date formats
follow the formats at
`datetime pattern <https://spark.apache.org/docs/latest/sql-ref-datetime-pattern.html>`_. # noqa
This applies to date type. If None is set, it uses the
default value, ``yyyy-MM-dd``.
timestampFormat : str, optional
sets the string that indicates a timestamp format.
Custom date formats follow the formats at
`datetime pattern <https://spark.apache.org/docs/latest/sql-ref-datetime-pattern.html>`_. # noqa
This applies to timestamp type. If None is set, it uses the
default value, ``yyyy-MM-dd'T'HH:mm:ss[.SSS][XXX]``.
maxColumns : str or int, optional
defines a hard limit of how many columns a record can have. If None is
set, it uses the default value, ``20480``.
maxCharsPerColumn : str or int, optional
defines the maximum number of characters allowed for any given
value being read. If None is set, it uses the default value,
``-1`` meaning unlimited length.
maxMalformedLogPerPartition : str or int, optional
this parameter is no longer used since Spark 2.2.0.
If specified, it is ignored.
mode : str, optional
allows a mode for dealing with corrupt records during parsing. If None is
set, it uses the default value, ``PERMISSIVE``.
* ``PERMISSIVE``: when it meets a corrupted record, puts the malformed string \
into a field configured by ``columnNameOfCorruptRecord``, and sets malformed \
fields to ``null``. To keep corrupt records, an user can set a string type \
field named ``columnNameOfCorruptRecord`` 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, \
sets ``null`` 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 : str, optional
allows renaming the new field having malformed string
created by ``PERMISSIVE`` mode. This overrides
``spark.sql.columnNameOfCorruptRecord``. If None is set,
it uses the value specified in
``spark.sql.columnNameOfCorruptRecord``.
multiLine : str or bool, optional
parse one record, which may span multiple lines. If None is
set, it uses the default value, ``false``.
charToEscapeQuoteEscaping : str, optional
sets a single character used for escaping the escape for
the quote character. If None is set, the default value is
escape character when escape and quote characters are
different, ``\0`` otherwise.
emptyValue : str, optional
sets the string representation of an empty value. If None is set, it uses
the default value, empty string.
locale : str, optional
sets a locale as language tag in IETF BCP 47 format. If None is set,
it uses the default value, ``en-US``. For instance, ``locale`` is used while
parsing dates and timestamps.
lineSep : str, optional
defines the line separator that should be used for parsing. If None is
set, it covers all ``\\r``, ``\\r\\n`` and ``\\n``.
Maximum length is 1 character.
pathGlobFilter : str or bool, optional
an optional glob pattern to only include files with paths matching
the pattern. The syntax follows `org.apache.hadoop.fs.GlobFilter`.
It does not change the behavior of
`partition discovery <https://spark.apache.org/docs/latest/sql-data-sources-parquet.html#partition-discovery>`_. # noqa
recursiveFileLookup : str or bool, optional
recursively scan a directory for files. Using this option disables
`partition discovery <https://spark.apache.org/docs/latest/sql-data-sources-parquet.html#partition-discovery>`_. # noqa
unescapedQuoteHandling : str, optional
defines how the CsvParser will handle values with unescaped quotes. If None is
set, it uses the default value, ``STOP_AT_DELIMITER``.
* ``STOP_AT_CLOSING_QUOTE``: If unescaped quotes are found in the input, accumulate
the quote character and proceed parsing the value as a quoted value, until a closing
quote is found.
* ``BACK_TO_DELIMITER``: If unescaped quotes are found in the input, consider the value
as an unquoted value. This will make the parser accumulate all characters of the current
parsed value until the delimiter is found. If no delimiter is found in the value, the
parser will continue accumulating characters from the input until a delimiter or line
ending is found.
* ``STOP_AT_DELIMITER``: If unescaped quotes are found in the input, consider the value
as an unquoted value. This will make the parser accumulate all characters until the
delimiter or a line ending is found in the input.
* ``SKIP_VALUE``: If unescaped quotes are found in the input, the content parsed
for the given value will be skipped and the value set in nullValue will be produced
instead.
* ``RAISE_ERROR``: If unescaped quotes are found in the input, a TextParsingException
will be thrown.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
Examples
--------
>>> csv_sdf = spark.readStream.csv(tempfile.mkdtemp(), schema = sdf_schema)
>>> csv_sdf.isStreaming
True
>>> csv_sdf.schema == sdf_schema
True
"""
self._set_opts(
schema=schema, sep=sep, encoding=encoding, quote=quote, escape=escape, comment=comment,
header=header, inferSchema=inferSchema, ignoreLeadingWhiteSpace=ignoreLeadingWhiteSpace,
ignoreTrailingWhiteSpace=ignoreTrailingWhiteSpace, nullValue=nullValue,
nanValue=nanValue, positiveInf=positiveInf, negativeInf=negativeInf,
dateFormat=dateFormat, timestampFormat=timestampFormat, maxColumns=maxColumns,
maxCharsPerColumn=maxCharsPerColumn,
maxMalformedLogPerPartition=maxMalformedLogPerPartition, mode=mode,
columnNameOfCorruptRecord=columnNameOfCorruptRecord, multiLine=multiLine,
charToEscapeQuoteEscaping=charToEscapeQuoteEscaping, enforceSchema=enforceSchema,
emptyValue=emptyValue, locale=locale, lineSep=lineSep,
pathGlobFilter=pathGlobFilter, recursiveFileLookup=recursiveFileLookup,
unescapedQuoteHandling=unescapedQuoteHandling)
if isinstance(path, str):
return self._df(self._jreader.csv(path))
else:
raise TypeError("path can be only a single string")
def table(self, tableName):
"""Define a Streaming DataFrame on a Table. The DataSource corresponding to the table should
support streaming mode.
.. versionadded:: 3.1.0
Parameters
----------
tableName : str
string, for the name of the table.
Returns
--------
:class:`DataFrame`
Notes
-----
This API is evolving.
Examples
--------
>>> spark.readStream.table('input_table') # doctest: +SKIP
"""
if isinstance(tableName, str):
return self._df(self._jreader.table(tableName))
else:
raise TypeError("tableName can be only a single string")
class DataStreamWriter(object):
"""
Interface used to write a streaming :class:`DataFrame <pyspark.sql.DataFrame>` to external
storage systems (e.g. file systems, key-value stores, etc).
Use :attr:`DataFrame.writeStream <pyspark.sql.DataFrame.writeStream>`
to access this.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
"""
def __init__(self, df):
self._df = df
self._spark = df.sql_ctx
self._jwrite = df._jdf.writeStream()
def _sq(self, jsq):
from pyspark.sql.streaming import StreamingQuery
return StreamingQuery(jsq)
def outputMode(self, outputMode):
"""Specifies how data of a streaming DataFrame/Dataset is written to a streaming sink.
.. versionadded:: 2.0.0
Options include:
* `append`: Only the new rows in the streaming DataFrame/Dataset will be written to
the sink
* `complete`: All the rows in the streaming DataFrame/Dataset will be written to the sink
every time these are some updates
* `update`: only the rows that were updated in the streaming DataFrame/Dataset will be
written to the sink every time there are some updates. If the query doesn't contain
aggregations, it will be equivalent to `append` mode.
Notes
-----
This API is evolving.
Examples
--------
>>> writer = sdf.writeStream.outputMode('append')
"""
if not outputMode or type(outputMode) != str or len(outputMode.strip()) == 0:
raise ValueError('The output mode must be a non-empty string. Got: %s' % outputMode)
self._jwrite = self._jwrite.outputMode(outputMode)
return self
def format(self, source):
"""Specifies the underlying output data source.
.. versionadded:: 2.0.0
Parameters
----------
source : str
string, name of the data source, which for now can be 'parquet'.
Notes
-----
This API is evolving.
Examples
--------
>>> writer = sdf.writeStream.format('json')
"""
self._jwrite = self._jwrite.format(source)
return self
def option(self, key, value):
"""Adds an output option for the underlying data source.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
"""
self._jwrite = self._jwrite.option(key, to_str(value))
return self
def options(self, **options):
"""Adds output options for the underlying data source.
.. versionadded:: 2.0.0
Notes
-----
This API is evolving.
"""
for k in options:
self._jwrite = self._jwrite.option(k, to_str(options[k]))
return self
def partitionBy(self, *cols):
"""Partitions the output by the given columns on the file system.
If specified, the output is laid out on the file system similar
to Hive's partitioning scheme.
.. versionadded:: 2.0.0
Parameters
----------
cols : str or list
name of columns
Notes
-----
This API is evolving.
"""
if len(cols) == 1 and isinstance(cols[0], (list, tuple)):
cols = cols[0]
self._jwrite = self._jwrite.partitionBy(_to_seq(self._spark._sc, cols))
return self
def queryName(self, queryName):
"""Specifies the name of the :class:`StreamingQuery` that can be started with
:func:`start`. This name must be unique among all the currently active queries
in the associated SparkSession.
.. versionadded:: 2.0.0
Parameters
----------
queryName : str
unique name for the query
Notes
-----
This API is evolving.
Examples
--------
>>> writer = sdf.writeStream.queryName('streaming_query')
"""
if not queryName or type(queryName) != str or len(queryName.strip()) == 0:
raise ValueError('The queryName must be a non-empty string. Got: %s' % queryName)
self._jwrite = self._jwrite.queryName(queryName)
return self