[carbondata] branch master updated: [HOTFIX] Fixed count(*) issue when MV is created with simple projection

[ku...@apache.org]

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kunalkapoor pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/carbondata.git


The following commit(s) were added to refs/heads/master by this push:
     new 14f170c  [HOTFIX] Fixed count(*) issue when MV is created with simple projection
14f170c is described below

commit 14f170c5daf32febc536444ce441f8ba0d0fa143
Author: ravipesala <ra...@gmail.com>
AuthorDate: Tue May 21 17:40:56 2019 +0530

    [HOTFIX] Fixed count(*) issue when MV is created with simple projection
    
    Problem:
    When MV is created with simple projection and select count(*) is fired
    on main table then it is wrongly taking MV table with wrong projections.
    
    Solution:
    Simple projection MV should not be selected when count(*) is fired.
    
    This closed #3229
---
 .../apache/carbondata/mv/rewrite/DefaultMatchMaker.scala    |  4 +++-
 .../org/apache/carbondata/mv/rewrite/MVCreateTestCase.scala | 13 +++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/datamap/mv/core/src/main/scala/org/apache/carbondata/mv/rewrite/DefaultMatchMaker.scala b/datamap/mv/core/src/main/scala/org/apache/carbondata/mv/rewrite/DefaultMatchMaker.scala
index 59d72f8..bd412e7 100644
--- a/datamap/mv/core/src/main/scala/org/apache/carbondata/mv/rewrite/DefaultMatchMaker.scala
+++ b/datamap/mv/core/src/main/scala/org/apache/carbondata/mv/rewrite/DefaultMatchMaker.scala
@@ -179,7 +179,9 @@ object SelectSelectNoChildDelta extends DefaultMatchPattern with PredicateHelper
           sel_1q.predicateList.exists(_.semanticEquals(expr)))
         val isPredicateEmdR = sel_1q.predicateList.forall(expr =>
           isDerivable(expr, sel_1a.outputList ++ rejoinOutputList, sel_1q, sel_1a, None))
-        val isOutputEdR = sel_1q.outputList.forall(expr =>
+        // Check if sel_1q.outputList is non empty and then check whether
+        // it can be derivable with sel_1a otherwise for empty cases it returns true.
+        val isOutputEdR = sel_1q.outputList.nonEmpty && sel_1q.outputList.forall(expr =>
           isDerivable(expr, sel_1a.outputList ++ rejoinOutputList, sel_1q, sel_1a, None))
 
         if (isUniqueRmE.isEmpty && isUniqueEmR.isEmpty && extrajoin.isEmpty && isPredicateRmE &&
diff --git a/datamap/mv/core/src/test/scala/org/apache/carbondata/mv/rewrite/MVCreateTestCase.scala b/datamap/mv/core/src/test/scala/org/apache/carbondata/mv/rewrite/MVCreateTestCase.scala
index e025623..a8abdc3 100644
--- a/datamap/mv/core/src/test/scala/org/apache/carbondata/mv/rewrite/MVCreateTestCase.scala
+++ b/datamap/mv/core/src/test/scala/org/apache/carbondata/mv/rewrite/MVCreateTestCase.scala
@@ -1061,6 +1061,19 @@ class MVCreateTestCase extends QueryTest with BeforeAndAfterAll {
     assert(TestUtil.verifyMVDataMap(analyzed3, "single_mv"))
   }
 
+  test("count test case") {
+
+    sql("drop table if exists mvtable1")
+    sql("create table mvtable1(name string,age int,salary int) stored by 'carbondata'")
+    sql("create datamap MV11 using 'mv' as select name from mvtable1")
+    sql("insert into mvtable1 select 'n1',12,12")
+    sql("rebuild datamap MV11")
+    val frame = sql("select count(*) from mvtable1")
+    assert(!TestUtil.verifyMVDataMap(frame.queryExecution.analyzed, "MV11"))
+    checkAnswer(frame,Seq(Row(1)))
+    sql("drop table if exists mvtable1")
+  }
+
   def verifyMVDataMap(logicalPlan: LogicalPlan, dataMapName: String): Boolean = {
     val tables = logicalPlan collect {
       case l: LogicalRelation => l.catalogTable.get