I have a bit of a strange one. I have loads of logs that I need to trawl. I have done that successfully in Spark & I am happy with it.
However, I need to add one more field to the dataframe, which is the data center.
The only place that the datacenter name can be derived is from the directory path.
For example:
/feedname/date/datacenter/another/logfile.txt
What would be the way to extract the log file path and inject it into the dataframe? From there, I can do some string splits & extract the bit I need.
My current code:
mpe_data = my_spark.read\
.option("header","false")\
.option("delimiter", "\t")\
.withColumn("Datacenter", input_file_name())\
.csv('hdfs://nameservice/data/feed/mpe/dt=20191013/*/*/*', final_structure)
mpe_data.printSchema()
mpe_data.createOrReplaceTempView("mpe")
You can get the file path using the _input_file_name_ in Spark 2.0+
from pyspark.sql.functions import input_file_name
df.withColumn("Datacenter", input_file_name())
Adding your piece of code as example, once you have read your file use the withcolumn to get the file_name.
mpe_data = my_spark.read\
.option("header","false")\
.option("delimiter", "\t")\
.csv('hdfs://nameservice/data/feed/mpe/dt=20191013/*/*/*', final_structure)
mpe_data.withColumn("Datacenter", input_file_name())
mpe_data.printSchema()
I am using spark streaming and I want to save each batch of spark streaming on my local in Avro format. I have used saveAsNewAPIHadoopFile to save data in Avro format. This works well. But it overwrites the existing file. Next batch data will overwrite the old data. Is there any way to save Avro file in common directory? I tried by adding some properties of Hadoop job conf for adding a prefix in the file name. But not working any properties.
dstream.foreachRDD {
rdd.saveAsNewAPIHadoopFile(
path,
classOf[AvroKey[T]],
classOf[NullWritable],
classOf[AvroKeyOutputFormat[T]],
job.getConfiguration()
)
}
Try this -
You can make your process split into 2 steps :
Step-01 :- Write Avro file using saveAsNewAPIHadoopFile to <temp-path>
Step-02 :- Move file from <temp-path> to <actual-target-path>
This will definitely solve your problem for now. I will share my thoughts if I get to fulfill this scenario in one step instead of two.
Hope this is helpful.
I am trying to save Dataframe as CSV file, I want to retain the spaces. I am using Spark 2.1.1, But when I try to save it as CSV file, all the spaces are trimmed.
I tried these options, but they didn't work.
option("ignoreLeadingWhiteSpace",false")
.option("ignoreTrailingWhiteSpace", "false")
Expected CSV format
SiteNumber, batch ,DayBatchDate,RecordType
190000, TBD, 12/12/2017, +00000001
My current output:
SiteNumber, batch ,DayBatchDate,RecordType
190000,TBD,12/12/2017,+00000001
ignoreLeadingWhiteSpace and ignoreTrailingWhiteSpace options for the writer have been introduced in Spark 2.2 (
SPARK-18579) so won't have effect in Spark 2.1.
I am sure there is documentation for this somewhere and/or the solution is obvious, but I've come up dry in all of my searching.
I have a dataframe that I want to export to a text file to my local machine. The dataframe contains strings with commas, so just display -> download full results ends up with a distorted export. I'd like to export out with a tab-delimiter, but I cannot figure out for the life of me how to download it locally.
I have
match1.write.format("com.databricks.spark.csv")
.option("delimiter", "\t")
.save("file:\\\C:\\Users\\user\\Desktop\\NewsArticle.txt")
but clearly this isn't right. I suspect it is writing somewhere else (somewhere I don't want it to be...) because running it again gives me the error that the path already exists. So... what is the correct way?
cricket_007 pointed me along the right path--ultimately, I needed to save the file to the Filestore of Databricks (not just dbfs), and then save the resulting output of the xxxxx.databricks.com/file/[insert file path here] link.
My resulting code was:
df.repartition(1) \ #repartitioned to save as one collective file
.write.format('csv') \ #in csv format
.option("header", True) \ #with header
.option("quote", "") \ #get rid of quote escaping
.option(delimiter="\t") \ #delimiter of choice
.save('dbfs:/FileStore/df/') #saved to the FileStore
Check if it is present at below location. Multiple part files should be there in that folder.
import os
print os.getcwd()
If you want to create a single file (not multiple part files) then you can use coalesce()(but note that it'll force one worker to fetch whole data and write these sequentially so it's not advisable if dealing with huge data)
df.coalesce(1).write.format("csv").\
option("delimiter", "\t").\
save("<file path>")
Hope this helps!
I have a spark streaming application which produces a dataset for every minute.
I need to save/overwrite the results of the processed data.
When I tried to overwrite the dataset org.apache.hadoop.mapred.FileAlreadyExistsException stops the execution.
I set the Spark property set("spark.files.overwrite","true") , but there is no luck.
How to overwrite or Predelete the files from spark?
UPDATE: Suggest using Dataframes, plus something like ... .write.mode(SaveMode.Overwrite) ....
Handy pimp:
implicit class PimpedStringRDD(rdd: RDD[String]) {
def write(p: String)(implicit ss: SparkSession): Unit = {
import ss.implicits._
rdd.toDF().as[String].write.mode(SaveMode.Overwrite).text(p)
}
}
For older versions try
yourSparkConf.set("spark.hadoop.validateOutputSpecs", "false")
val sc = SparkContext(yourSparkConf)
In 1.1.0 you can set conf settings using the spark-submit script with the --conf flag.
WARNING (older versions): According to #piggybox there is a bug in Spark where it will only overwrite files it needs to to write it's part- files, any other files will be left unremoved.
since df.save(path, source, mode) is deprecated, (http://spark.apache.org/docs/1.5.0/api/scala/index.html#org.apache.spark.sql.DataFrame)
use df.write.format(source).mode("overwrite").save(path)
where df.write is DataFrameWriter
'source' can be ("com.databricks.spark.avro" | "parquet" | "json")
From the pyspark.sql.DataFrame.save documentation (currently at 1.3.1), you can specify mode='overwrite' when saving a DataFrame:
myDataFrame.save(path='myPath', source='parquet', mode='overwrite')
I've verified that this will even remove left over partition files. So if you had say 10 partitions/files originally, but then overwrote the folder with a DataFrame that only had 6 partitions, the resulting folder will have the 6 partitions/files.
See the Spark SQL documentation for more information about the mode options.
The documentation for the parameter spark.files.overwrite says this: "Whether to overwrite files added through SparkContext.addFile() when the target file exists and its contents do not match those of the source." So it has no effect on saveAsTextFiles method.
You could do this before saving the file:
val hadoopConf = new org.apache.hadoop.conf.Configuration()
val hdfs = org.apache.hadoop.fs.FileSystem.get(new java.net.URI("hdfs://localhost:9000"), hadoopConf)
try { hdfs.delete(new org.apache.hadoop.fs.Path(filepath), true) } catch { case _ : Throwable => { } }
Aas explained here:
http://apache-spark-user-list.1001560.n3.nabble.com/How-can-I-make-Spark-1-0-saveAsTextFile-to-overwrite-existing-file-td6696.html
df.write.mode('overwrite').parquet("/output/folder/path") works if you want to overwrite a parquet file using python. This is in spark 1.6.2. API may be different in later versions
val jobName = "WordCount";
//overwrite the output directory in spark set("spark.hadoop.validateOutputSpecs", "false")
val conf = new
SparkConf().setAppName(jobName).set("spark.hadoop.validateOutputSpecs", "false");
val sc = new SparkContext(conf)
This overloaded version of the save function works for me:
yourDF.save(outputPath, org.apache.spark.sql.SaveMode.valueOf("Overwrite"))
The example above would overwrite an existing folder. The savemode can take these parameters as well (https://spark.apache.org/docs/1.4.0/api/java/org/apache/spark/sql/SaveMode.html):
Append: Append mode means that when saving a DataFrame to a data source, if data/table already exists, contents of the DataFrame are expected to be appended to existing data.
ErrorIfExists: ErrorIfExists mode means that when saving a DataFrame to a data source, if data already exists, an exception is expected to be thrown.
Ignore: Ignore mode means that when saving a DataFrame to a data source, if data already exists, the save operation is expected to not save the contents of the DataFrame and to not change the existing data.
Spark – Overwrite the output directory:
Spark by default doesn’t overwrite the output directory on S3, HDFS, and any other file systems, when you try to write the DataFrame contents to an existing directory, Spark returns runtime error hence. To overcome this Spark provides an enumeration org.apache.spark.sql.SaveMode.Overwrite to overwrite the existing folder.
We need to use this Overwrite as an argument to mode() function of the DataFrameWrite class, for example.
df. write.mode(SaveMode.Overwrite).csv("/tmp/out/foldername")
or you can use the overwrite string.
df.write.mode("overwrite").csv("/tmp/out/foldername")
Besides Overwrite, SaveMode also offers other modes like SaveMode.Append, SaveMode.ErrorIfExists and SaveMode.Ignore
For older versions of Spark, you can use the following to overwrite the output directory with the RDD contents.
sparkConf.set("spark.hadoop.validateOutputSpecs", "false")
val sparkContext = SparkContext(sparkConf)
If you are willing to use your own custom output format, you would be able to get the desired behaviour with RDD as well.
Have a look at the following classes:
FileOutputFormat,
FileOutputCommitter
In file output format you have a method named checkOutputSpecs, which is checking whether the output directory exists.
In FileOutputCommitter you have the commitJob which is usually transferring data from the temporary directory to its final place.
I wasn't able to verify it yet (would do it, as soon as I have few free minutes) but theoretically: If I extend FileOutputFormat and override checkOutputSpecs to a method that doesn't throw exception on directory already exists, and adjust the commitJob method of my custom output committer to perform which ever logic that I want (e.g. Override some of the files, append others) than I may be able to achieve the desired behaviour with RDDs as well.
The output format is passed to: saveAsNewAPIHadoopFile (which is the method saveAsTextFile called as well to actually save the files). And the Output committer is configured at the application level.