[SPARK-11677][SQL] ORC filter tests all pass if filters are actually not pushed down.

Currently ORC filters are not tested properly. All the tests pass even if the filters are not pushed down or disabled. In this PR, I add some logics for this.
Since ORC does not filter record by record fully, this checks the count of the result and if it contains the expected values.

Author: hyukjinkwon <[email protected]>

Closes #9687 from HyukjinKwon/SPARK-11677.

Author: HyukjinKwon

sql/hive/src/test/scala/org/apache/spark/sql/hive/orc/OrcQuerySuite.scala

@@ -350,28 +350,47 @@ class OrcQuerySuite extends QueryTest with BeforeAndAfterAll with OrcTest {
     withTempPath { dir =>
       withSQLConf(SQLConf.ORC_FILTER_PUSHDOWN_ENABLED.key -> "true") {
         import testImplicits._
-
         val path = dir.getCanonicalPath
-        sqlContext.range(10).coalesce(1).write.orc(path)
+
+        // For field "a", the first column has odds integers. This is to check the filtered count
+        // when `isNull` is performed. For Field "b", `isNotNull` of ORC file filters rows
+        // only when all the values are null (maybe this works differently when the data
+        // or query is complicated). So, simply here a column only having `null` is added.
+        val data = (0 until 10).map { i =>
+          val maybeInt = if (i % 2 == 0) None else Some(i)
+          val nullValue: Option[String] = None
+          (maybeInt, nullValue)
+        }
+        createDataFrame(data).toDF("a", "b").write.orc(path)
         val df = sqlContext.read.orc(path)
 
-        def checkPredicate(pred: Column, answer: Seq[Long]): Unit = {
-          checkAnswer(df.where(pred), answer.map(Row(_)))
+        def checkPredicate(pred: Column, answer: Seq[Row]): Unit = {
+          val sourceDf = stripSparkFilter(df.where(pred))
+          val data = sourceDf.collect().toSet
+          val expectedData = answer.toSet
+
+          // When a filter is pushed to ORC, ORC can apply it to rows. So, we can check
+          // the number of rows returned from the ORC to make sure our filter pushdown work.
+          // A tricky part is, ORC does not process filter rows fully but return some possible
+          // results. So, this checks if the number of result is less than the original count
+          // of data, and then checks if it contains the expected data.
+          val isOrcFiltered = sourceDf.count < 10 && expectedData.subsetOf(data)
+          assert(isOrcFiltered)
         }
 
-        checkPredicate('id === 5, Seq(5L))
-        checkPredicate('id <=> 5, Seq(5L))
-        checkPredicate('id < 5, 0L to 4L)
-        checkPredicate('id <= 5, 0L to 5L)
-        checkPredicate('id > 5, 6L to 9L)
-        checkPredicate('id >= 5, 5L to 9L)
-        checkPredicate('id.isNull, Seq.empty[Long])
-        checkPredicate('id.isNotNull, 0L to 9L)
-        checkPredicate('id.isin(1L, 3L, 5L), Seq(1L, 3L, 5L))
-        checkPredicate('id > 0 && 'id < 3, 1L to 2L)
-        checkPredicate('id < 1 || 'id > 8, Seq(0L, 9L))
-        checkPredicate(!('id > 3), 0L to 3L)
-        checkPredicate(!('id > 0 && 'id < 3), Seq(0L) ++ (3L to 9L))
+        checkPredicate('a === 5, List(5).map(Row(_, null)))
+        checkPredicate('a <=> 5, List(5).map(Row(_, null)))
+        checkPredicate('a < 5, List(1, 3).map(Row(_, null)))
+        checkPredicate('a <= 5, List(1, 3, 5).map(Row(_, null)))
+        checkPredicate('a > 5, List(7, 9).map(Row(_, null)))
+        checkPredicate('a >= 5, List(5, 7, 9).map(Row(_, null)))
+        checkPredicate('a.isNull, List(null).map(Row(_, null)))
+        checkPredicate('b.isNotNull, List())
+        checkPredicate('a.isin(3, 5, 7), List(3, 5, 7).map(Row(_, null)))
+        checkPredicate('a > 0 && 'a < 3, List(1).map(Row(_, null)))
+        checkPredicate('a < 1 || 'a > 8, List(9).map(Row(_, null)))
+        checkPredicate(!('a > 3), List(1, 3).map(Row(_, null)))
+        checkPredicate(!('a > 0 && 'a < 3), List(3, 5, 7, 9).map(Row(_, null)))
       }
     }
   }