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Author: adrian-wang

sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala

@@ -159,6 +159,9 @@ class TestHiveContext(sc: SparkContext) extends HiveContext(sc) {
   protected[hive] class HiveQLQueryExecution(hql: String)
     extends this.SubstitutedHiveQLQueryExecution(vs.substitute(hiveconf, hql))
 
+  // we should substitute variables in hql to pass the text to parseSql() as a parameter.
+  // Hive parser need substituted text. HiveContext.sql() does this but return a DataFrame,
+  // while we need a logicalPlan so we cannot reuse that.
   protected[hive] class SubstitutedHiveQLQueryExecution(hql: String)
     extends this.QueryExecution(HiveQl.parseSql(hql)) {
     def hiveExec(): Seq[String] = runSqlHive(hql)