Hello I need to read the data from gz.parquet files but dont know how to?? Tried with impala but i get the same result as parquet-tools cat
without the table structure.
P.S: any suggestions to improve the spark code are most welcome.
I have the following parquet files gz.parquet
as a result of a data pipe line created by twitter => flume => kafka => spark streaming => hive/gz.parquet files). For flume agent i am using agent1.sources.twitter-data.type = org.apache.flume.source.twitter.TwitterSource
Spark code de-queues the data from kafka and storing in hive as follows:
val sparkConf = new SparkConf().setAppName("KafkaTweet2Hive")
val sc = new SparkContext(sparkConf)
val ssc = new StreamingContext(sc, Seconds(2))
val sqlContext = new org.apache.spark.sql.hive.HiveContext(sc)//new org.apache.spark.sql.SQLContext(sc)
// Create direct kafka stream with brokers and topics
val topicsSet = topics.split(",").toSet
val kafkaParams = Map[String, String]("metadata.broker.list" -> brokers)
val messages = KafkaUtils.createDirectStream[String, String, StringDecoder, StringDecoder](ssc, kafkaParams, topicsSet)
// Get the data (tweets) from kafka
val tweets = messages.map(_._2)
// adding the tweets to Hive
tweets.foreachRDD { rdd =>
val hiveContext = SQLContext.getOrCreate(rdd.sparkContext)
import sqlContext.implicits._
val tweetsDF = rdd.toDF()
tweetsDF.write.mode("append").saveAsTable("tweet")
}
When i run the spark-streaming
app it stores the data as gz.parquet
files in hdfs: /user/hive/warehouse
directory as follows:
[root@quickstart /]# hdfs dfs -ls /user/hive/warehouse/tweets
Found 469 items
-rw-r--r-- 1 root supergroup 0 2016-03-30 08:36 /user/hive/warehouse/tweets/_SUCCESS
-rw-r--r-- 1 root supergroup 241 2016-03-30 08:36 /user/hive/warehouse/tweets/_common_metadata
-rw-r--r-- 1 root supergroup 35750 2016-03-30 08:36 /user/hive/warehouse/tweets/_metadata
-rw-r--r-- 1 root supergroup 23518 2016-03-30 08:33 /user/hive/warehouse/tweets/part-r-00000-0133fcd1-f529-4dd1-9371-36bf5c3e5df3.gz.parquet
-rw-r--r-- 1 root supergroup 9552 2016-03-30 08:33 /user/hive/warehouse/tweets/part-r-00000-02c44f98-bfc3-47e3-a8e7-62486a1a45e7.gz.parquet
-rw-r--r-- 1 root supergroup 19228 2016-03-30 08:25 /user/hive/warehouse/tweets/part-r-00000-0321ce99-9d2b-4c52-82ab-a9ed5f7d5036.gz.parquet
-rw-r--r-- 1 root supergroup 241 2016-03-30 08:25 /user/hive/warehouse/tweets/part-r-00000-03415df3-c719-4a3a-90c6 462c43cfef54.gz.parquet
The schema from _metadata
file is as follows:
[root@quickstart /]# parquet-tools meta hdfs://quickstart.cloudera:8020/user/hive/warehouse/tweets/_metadata
creator: parquet-mr version 1.5.0-cdh5.5.0 (build ${buildNumber})
extra: org.apache.spark.sql.parquet.row.metadata = {"type":"struct","fields":[{"name":"tweet","type":"string","nullable":true,"metadata":{}}]}
file schema: root
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
tweet: OPTIONAL BINARY O:UTF8 R:0 D:1
Furthermore, if i load the data into a dataframe in spark i get the output of `df.show´ as follows:
+--------------------+
| tweet|
+--------------------+
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|ڕObjavro.sch...|
|��Objavro.sc...|
|ֲObjavro.sch...|
|��Objavro.sc...|
|��Objavro.sc...|
|֕Objavro.sch...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
|��Objavro.sc...|
+--------------------+
only showing top 20 rows
How ever i would like to see the tweets as plain text?
sqlContext.read.parquet("/user/hive/warehouse/tweets").show