Adding an example with an OLAP roll-up

examples/src/main/scala/spark/examples/OLAPQuery.scala

+package spark.examples
+
+import spark.SparkContext
+import spark.SparkContext._
+/**
+ * Executes a roll up-style query against Apache logs.
+ */
+object OLAPQuery {
+  val exampleApacheLogs = List(
+    """10.10.10.10 - "FRED" [18/Jan/2013:17:56:07 +1100] "GET http://images.com/2013/Generic.jpg
+      | HTTP/1.1" 304 315 "http://referall.com/" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1;
+      | GTB7.4; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR
+      | 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 1.0.3705; .NET CLR 1.1.4322; .NET CLR
+      | 3.5.30729; Release=ARP)" "UD-1" - "image/jpeg" "whatever" 0.350 "-" - "" 265 923 934 ""
+      | 62.24.11.25 images.com 1358492167 - Whatup""".stripMargin.replace("\n", ""),
+    """10.10.10.10 - "FRED" [18/Jan/2013:18:02:37 +1100] "GET http://images.com/2013/Generic.jpg
+      | HTTP/1.1" 304 306 "http:/referall.com" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1;
+      | GTB7.4; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR
+      | 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 1.0.3705; .NET CLR 1.1.4322; .NET CLR
+      | 3.5.30729; Release=ARP)" "UD-1" - "image/jpeg" "whatever" 0.352 "-" - "" 256 977 988 ""
+      | 0 73.23.2.15 images.com 1358492557 - Whatup""".stripMargin.replace("\n", "")
+  )
+
+  def main(args: Array[String]) {
+    if (args.length == 0) {
+      System.err.println("Usage: OLAPQuery <master> [logFile]")
+      System.exit(1)
+    }
+    val sc = new SparkContext(args(0), "OLAP Query")
+
+    val dataSet =
+      if (args.length == 2) sc.textFile(args(1))
+      else sc.parallelize(exampleApacheLogs)
+
+    val apache_log_regex =
+      """^([\d.]+) (\S+) (\S+) \[([\w\d:/]+\s[+\-]\d{4})\] "(.+?)" (\d{3}) ([\d\-]+) "([^"]+)" "([^"]+)".*""".r
+
+    /** Tracks the total query count and number of aggregate bytes for a particular group. */
+    class Stats(val count: Int, val numBytes: Int) extends Serializable {
+      def merge(other: Stats) = new Stats(count + other.count, numBytes + other.numBytes)
+      override def toString = "bytes=%s\tn=%s".format(numBytes, count)
+    }
+
+    def extractKey(line: String): (String, String, String) = {
+      apache_log_regex findFirstIn line match {
+        case Some(apache_log_regex(ip, _, user, dateTime, query, status, bytes, referer, ua)) =>
+          if (user != "\"-\"") (ip, user, query)
+          else (null, null, null)
+        case _ => (null, null, null)
+      }
+    }
+
+    def extractStats(line: String): Stats = {
+      apache_log_regex findFirstIn line match {
+        case Some(apache_log_regex(ip, _, user, dateTime, query, status, bytes, referer, ua)) =>
+          new Stats(1, bytes.toInt)
+        case _ => new Stats(1, 0)
+      }
+    }
+
+    dataSet.map(line => (extractKey(line), extractStats(line)))
+      .reduceByKey((a, b) => a.merge(b))
+      .collect().foreach{
+        case (user, query) => println("%s\t%s".format(user, query))}
+  }
+}