## Using Glue Count Example This example provides scala script for counting the number of rows in a Amazon Keyspaces table using AWS Glue. This is common utility in verifying data in tables during migration or after bulk import. ## Prerequisites * Amazon Keyspaces table to count * Amazon S3 bucket to store required jars * Amazon S3 bucket to store job configuration and script * Amazon S3 bucket to store glue shuffle data ### Counting the number of rows in Amazon Keyspaces The following example uses the spark-cassandra-connector. The script takes three parameters KEYSPACE_NAME, KEYSPACE_TABLE, and DRIVER_CONF. DRIVER_CONF is the java driver external application.conf where all connection information is maintained. ``` import com.amazonaws.services.glue.GlueContext import com.amazonaws.services.glue.log.GlueLogger import com.amazonaws.services.glue.util.GlueArgParser import com.amazonaws.services.glue.util.Job import org.apache.spark.SparkContext import org.apache.spark.SparkConf import org.apache.spark.sql.Dataset import org.apache.spark.sql.Row import org.apache.spark.sql.SaveMode import org.apache.spark.sql.SparkSession import org.apache.spark.sql.functions.from_json import org.apache.spark.sql.streaming.Trigger import scala.collection.JavaConverters._ import com.datastax.spark.connector._ import org.apache.spark.sql.cassandra._ import org.apache.spark.sql.SaveMode._ object GlueApp { def main(sysArgs: Array[String]) { val args = GlueArgParser.getResolvedOptions(sysArgs, Seq("JOB_NAME", "KEYSPACE_NAME", "TABLE_NAME", "DRIVER_CONF").toArray) val driverConfFileName = args("DRIVER_CONF") val conf = new SparkConf() .setAll( Seq( ("spark.cassandra.connection.config.profile.path", driverConfFileName), ("spark.cassandra.query.retry.count", "100"), ("spark.cassandra.sql.inClauseToJoinConversionThreshold", "0"), ("spark.cassandra.sql.inClauseToFullScanConversionThreshold", "0"), ("spark.cassandra.concurrent.reads", "512"), ("spark.cassandra.output.concurrent.writes", "5"), ("spark.cassandra.output.batch.grouping.key", "none"), ("spark.cassandra.output.batch.size.rows", "1") )) val spark: SparkContext = new SparkContext(conf) val glueContext: GlueContext = new GlueContext(spark) val sparkSession: SparkSession = glueContext.getSparkSession import com.datastax.spark.connector._ import org.apache.spark.sql.cassandra._ import sparkSession.implicits._ Job.init(args("JOB_NAME"), glueContext, args.asJava) val tableName = args("TABLE_NAME") val keyspaceName = args("KEYSPACE_NAME") val tableDf = sparkSession.read .format("org.apache.spark.sql.cassandra") .options(Map( "table" -> tableName, "keyspace" -> keyspaceName)) .load() val total = tableDf.toJavaRDD.count() val logger = new GlueLogger logger.info("Total number of rows in table:" + total) Job.commit() } } ``` ## Update the partitioner for your account In Apache Cassandra, partitioners control which nodes data is stored on in the cluster. Partitioners create a numeric token using a hashed value of the partition key. Cassandra uses this token to distribute data across nodes. To use Apache Spark or AWS glue you will need to update the partitioner. You can execute this CQL command from the Amazon Keyspaces console [CQL editor](https://console.aws.amazon.com/keyspaces/home#cql-editor) ## Create IAM ROLE for AWS Glue Create a new AWS service role named 'GlueKeyspacesRole' with AWS Glue as a trusted entity. Included is a sample permissions-policy for executing Glue job. You can use managed policies AWSGlueServiceRole, AmazonKeyspacesReadOnlyAccess, read access to S3 bucket containing spack-cassandra-connector jar and configuration. ## Cassandra driver configuration to connect to Amazon Keyspaces The following configuration for connecting to Amazon Keyspaces with the spark-cassandra connector. Using the RateLimitingRequestThrottler we can ensure that request do not exceed configured Keyspaces capacity. The G1.X DPU creates one executor per worker. The RateLimitingRequestThrottler in this example is set for 1000 request per second. With this configuration and G.1X DPU you will achieve 1000 request per Glue worker. Adjust the max-requests-per-second accordingly to fit your workload. Increase the number of workers to scale throughput to a table. ``` datastax-java-driver { basic.request.consistency = "LOCAL_ONE" basic.request.default-idempotence = true basic.contact-points = [ "cassandra.us-east-1.amazonaws.com:9142"] advanced.reconnect-on-init = true basic.load-balancing-policy { local-datacenter = "us-east-1" } advanced.auth-provider = { class = PlainTextAuthProvider username = "user-at-sample" password = "SAMPLE#PASSWORD" } advanced.throttler = { class = RateLimitingRequestThrottler max-requests-per-second = 1000 max-queue-size = 50000 drain-interval = 1 millisecond } advanced.ssl-engine-factory { class = DefaultSslEngineFactory hostname-validation = false } advanced.connection.pool.local.size = 2 advanced.resolve-contact-points = false } ``` ## Create S3 bucket to store job artifacts The AWS Glue ETL job will need to access jar dependencies, driver configuration, and scala script. You can use the same bucket to store backups. ``` aws s3 mb s3://amazon-keyspaces-artifacts ``` ## Create S3 bucket for shuffle space With NoSQL its common to shuffle large sets of data. This can overflow local disk. With AWS Glue, you can use Amazon S3 to store Spark shuffle and spill data. This solution disaggregates compute and storage for your Spark jobs, and gives complete elasticity and low-cost shuffle storage, allowing you to run your most shuffle-intensive workloads reliably. ``` aws s3 mb s3://amazon-keyspaces-glue-shuffle ``` ## Upload job artifacts to S3 The job will require * The spark-cassandra-connector to allow reads from Amazon Keyspaces. Amazon Keyspaces recommends version 2.5.2 or above of the spark-cassandra-connector. * creation of S3 buckets * cassandra-application.conf containing the cassandra driver configuration for Keyspaces access * count-example.scala script containing the count code. ``` curl -L -O https://repo1.maven.org/maven2/com/datastax/spark/spark-cassandra-connector-assembly_2.11/2.5.2/spark-cassandra-connector-assembly_2.11-2.5.2.jar aws s3api put-object --bucket amazon-keyspaces-artifacts --key jars/spark-cassandra-connector-assembly_2.11-2.5.2.jar --body spark-cassandra-connector-assembly_2.11-2.5.2.jar aws s3api put-object --bucket amazon-keyspaces-artifacts --key conf/cassandra-application.conf --body cassandra-application.conf aws s3api put-object --bucket amazon-keyspaces-artifacts --key scripts/count-example.scala --body count-example.scala ``` ### Create AWS Glue ETL Job You can use the following command to create a glue job using the script provided in this example. You can also take the parameters and enter them into the AWS Console. ``` aws glue create-job \ --name "AmazonKeyspacesCount" \ --role "GlueKeyspacesRestore" \ --description "Count Rows in Amazon Keyspaces table" \ --glue-version "2.0" \ --number-of-workers 5 \ --worker-type "G.1X" \ --command "Name=glueetl,ScriptLocation=s3://amazon-keyspaces-artifacts/scripts/count-example.scala" \ --default-arguments '{ "--job-language":"scala", "--KEYSPACE_NAME":"my_keyspace", "--TABLE_NAME":"my_table", "--DRIVER_CONF":"cassandra-application.conf", "--extra-jars":"s3://amazon-keyspaces-artifacts/jars/spark-cassandra-connector-assembly_2.11-2.5.2.jar", "--extra-files":"s3://amazon-keyspaces-artifacts/conf/cassandra-application.conf", "--enable-continuous-cloudwatch-log":"true", "--write-shuffle-files-to-s3":"true", "--write-shuffle-spills-to-s3":"true", "--TempDir":"s3://amazon-keyspaces-glue-shuffle", "--class":"GlueApp" }' ```