[jira] [Created] (CALCITE-891) TableScan without Project cannot be substituted by any projected materialization

["Maryann Xue (JIRA)" <ji...@apache.org>]

Maryann Xue created CALCITE-891:
-----------------------------------

             Summary: TableScan without Project cannot be substituted by any projected materialization
                 Key: CALCITE-891
                 URL: https://issues.apache.org/jira/browse/CALCITE-891
             Project: Calcite
          Issue Type: Bug
            Reporter: Maryann Xue
            Assignee: Julian Hyde
            Priority: Minor


A TableScan that does not have a Project as its parent cannot be matched by any UnifyRules and thus cannot be substituted by a projected materialization; while the same TableScan with an identity projection could.

{code}
  @Test public void testJoinMaterialization2() {
    String q = "select *\n"
            + "from \"emps\"\n"
            + "join \"depts\" using (\"deptno\")";
    checkMaterialize("select \"deptno\", \"empid\", \"name\", \"salary\", \"commission\" from \"emps\"", q);
  }
{code}

In the above test case, the initial Rel was like:
{code}
LogicalProject(...)
  LogicalJoin(...)
    TableScan(table=[[hr, emps]])
    TableScan(table=[[hr, depts]])
{code}
And the queryDescendent {{TableScan(table=\[\[hr, emps\]\])}} cannot be matched by any UnifyRules that could have matched {{LogicalProject(<identity_project_list>, TableScan(table=\[\[hr, emps\]\]))}}.

The following changes would make this test case pass. Not sure if this would be the best fix, but it is at least a good illustration of the problem.
{code}
diff --git a/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java b/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java
index 7762bf7..ccece75 100644
--- a/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java
+++ b/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java
@@ -2861,9 +2861,6 @@ public static RelNode permute(
   public static RelNode createProject(final RelFactories.ProjectFactory factory,
       final RelNode child, final List<Integer> posList) {
     RelDataType rowType = child.getRowType();
-    if (Mappings.isIdentity(posList, rowType.getFieldCount())) {
-      return child;
-    }
     final List<String> fieldNames = rowType.getFieldNames();
     final RexBuilder rexBuilder = child.getCluster().getRexBuilder();
     return factory.createProject(child,
diff --git a/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java b/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java
index 50f22c1..b0a519a 100644
--- a/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java
+++ b/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java
@@ -2240,6 +2240,8 @@ protected RelNode createJoin(
       }
     }

+    leftRel = leftRel instanceof Project ? leftRel : RelOptUtil.createProject(leftRel, ImmutableIntList.identity(leftRel.getRowType().getFieldCount()));
+    rightRel = rightRel instanceof Project ? rightRel : RelOptUtil.createProject(rightRel, ImmutableIntList.identity(rightRel.getRowType().getFieldCount()));
     final Join originalJoin =
         (Join) RelFactories.DEFAULT_JOIN_FACTORY.createJoin(leftRel, rightRel,
             joinCond, joinType, ImmutableSet.<String>of(), false);
{code}



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)