Hi Michael,
I am wondering what I am doing wrong. I get error like:
Exception in thread "main" java.lang.IllegalArgumentException: Schema must
be specified when creating a streaming source DataFrame. If some files
already exist in the directory, then depending on the file format you may
be able to create a static DataFrame on that directory with
'spark.read.load(directory)' and infer schema from it.
at
org.apache.spark.sql.execution.datasources.DataSource.sourceSchema(DataSource.scala:223)
at
org.apache.spark.sql.execution.datasources.DataSource.sourceInfo$lzycompute(DataSource.scala:87)
at
org.apache.spark.sql.execution.datasources.DataSource.sourceInfo(DataSource.scala:87)
at
org.apache.spark.sql.execution.streaming.StreamingRelation$.apply(StreamingRelation.scala:30)
at
org.apache.spark.sql.streaming.DataStreamReader.load(DataStreamReader.scala:125)
at
org.apache.spark.sql.streaming.DataStreamReader.load(DataStreamReader.scala:134)
at
com.aol.persist.UplynkAggregates$.aggregator(UplynkAggregates.scala:23)
at com.aol.persist.UplynkAggregates$.main(UplynkAggregates.scala:41)
at com.aol.persist.UplynkAggregates.main(UplynkAggregates.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
17/09/12 14:46:22 INFO SparkContext: Invoking stop() from shutdown hook
I tried specifying the schema as well.
Here is my code:
object Aggregates {
val aggregation=
"""select sum(col1), sum(col2), id, first(name)
from enrichedtb
group by id
""".stripMargin
def aggregator(conf:Config)={
implicit val spark =
SparkSession.builder().appName(conf.getString("AppName")).getOrCreate()
implicit val sqlctx = spark.sqlContext
printf("Source path is" + conf.getString("source.path"))
val schemadf = sqlctx.read.parquet(conf.getString("source.path"))
// Added this as it was complaining about schema.
val df=spark.readStream.format("parquet").option("inferSchema",
true).schema(schemadf.schema).load(conf.getString("source.path"))
df.createOrReplaceTempView("enrichedtb")
val res = spark.sql(aggregation)
res.writeStream.format("parquet").outputMode("append").option("checkpointLocation",conf.getString("checkpointdir")).start(conf.getString("sink.outputpath"))
}
def main(args: Array[String]): Unit = {
val mainconf = ConfigFactory.load()
val conf = mainconf.getConfig(mainconf.getString("pipeline"))
print(conf.toString)
aggregator(conf)
}
}
I tried to extract schema from static read of the input path and
provided it to the readStream API. With that, I get this error:
at
org.apache.spark.sql.catalyst.analysis.UnsupportedOperationChecker$.org$apache$spark$sql$catalyst$analysis$UnsupportedOperationChecker$$throwError(UnsupportedOperationChecker.scala:297)
at
org.apache.spark.sql.catalyst.analysis.UnsupportedOperationChecker$.checkForStreaming(UnsupportedOperationChecker.scala:109)
at
org.apache.spark.sql.streaming.StreamingQueryManager.createQuery(StreamingQueryManager.scala:232)
at
org.apache.spark.sql.streaming.StreamingQueryManager.startQuery(StreamingQueryManager.scala:278)
at
org.apache.spark.sql.streaming.DataStreamWriter.start(DataStreamWriter.scala:282)
at
org.apache.spark.sql.streaming.DataStreamWriter.start(DataStreamWriter.scala:222)
While running on the EMR cluster all paths point to S3. In my laptop,
they all point to local filesystem.
I am using Spark2.2.0
Appreciate your help.
regards
Sunita
On Wed, Aug 23, 2017 at 2:30 PM, Michael Armbrust <mich...@databricks.com>
wrote:
> If you use structured streaming and the file sink, you can have a
> subsequent stream read using the file source. This will maintain exactly
> once processing even if there are hiccups or failures.
>
> On Mon, Aug 21, 2017 at 2:02 PM, Sunita Arvind <sunitarv...@gmail.com>
> wrote:
>
>> Hello Spark Experts,
>>
>> I have a design question w.r.t Spark Streaming. I have a streaming job
>> that consumes protocol buffer encoded real time logs from a Kafka cluster
>> on premise. My spark application runs on EMR (aws) and persists data onto
>> s3. Before I persist, I need to strip header and convert protobuffer to
>> parquet (I use sparksql-scalapb to convert from Protobuff to
>> Spark.sql.Row). I need to persist Raw logs as is. I can continue the
>> enrichment on the same dataframe after persisting the raw data, however, in
>> order to modularize I am planning to have a separate job which picks up the
>> raw data and performs enrichment on it. Also, I am trying to avoid all in
>> 1 job as the enrichments could get project specific while raw data
>> persistence stays customer/project agnostic.The enriched data is allowed to
>> have some latency (few minutes)
>>
>> My challenge is, after persisting the raw data, how do I chain the next
>> streaming job. The only way I can think of is - job 1 (raw data)
>> partitions on current date (YYYYMMDD) and within current date, the job 2
>> (enrichment job) filters for records within 60s of current time and
>> performs enrichment on it in 60s batches.
>> Is this a good option? It seems to be error prone. When either of the
>> jobs get delayed due to bursts or any error/exception this could lead to
>> huge data losses and non-deterministic behavior . What are other
>> alternatives to this?
>>
>> Appreciate any guidance in this regard.
>>
>> regards
>> Sunita Koppar
>>
>
>
