[CALCITE-1582] RelToSqlConverter doesn't handle cartesian join (no join cond)

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.12.0
• Component/s: core
• Assignee: Julian Hyde
• Reporter: Jess Balint
• Created: 17/Jan/17 15:08
• Updated: 16/May/17 12:46
• Resolved: 25/Jan/17 21:45

Description

this test fails (added in RelToSqlConverterTest):

  @Test public void testCartesianProduct() {
    String query = "select * from \"department\" , \"employee\"";
    String expected = "SELECT *\n" +
                      "FROM \"foodmart\".\"department\"\n" +
                      "INNER JOIN \"foodmart\".\"employee\"";
    sql(query).ok(expected);
  }

RelToSqlConverter is checking that the join condition is a RexCall. In this case (and RelBuilder.join() with no join cond), the join cond is a RexLiteral with a value of true.

Suggested fix is to handle the case with this specific join condition before convertConditionToSqlNode():

 --- a/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java
 +++ b/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java
 @@ -104,17 +104,23 @@ public Result visit(Join e) {
      final Context leftContext = leftResult.qualifiedContext();
      final Context rightContext =
          rightResult.qualifiedContext();
 -    SqlNode sqlCondition = convertConditionToSqlNode(e.getCondition(),
 -        leftContext,
 -        rightContext,
 -        e.getLeft().getRowType().getFieldCount());
 +    SqlNode sqlCondition = null;
 +    SqlLiteral condType = JoinConditionType.ON.symbol(POS);
 +    if (e.getCondition().isAlwaysTrue()) {
 +      condType = JoinConditionType.NONE.symbol(POS);
 +    } else {
 +      sqlCondition = convertConditionToSqlNode(e.getCondition(),
 +          leftContext,
 +          rightContext,
 +          e.getLeft().getRowType().getFieldCount());
 +    }
      SqlNode join =
          new SqlJoin(POS,
              leftResult.asFrom(),
              SqlLiteral.createBoolean(false, POS),
              joinType(e.getJoinType()).symbol(POS),
              rightResult.asFrom(),
 -            JoinConditionType.ON.symbol(POS),
 +            condType,
              sqlCondition);
      return result(join, leftResult, rightResult);
    }

Issue Links

• is cloned by: CALCITE-1792 RelToSqlConverter doesn't handle cartesian join (join cond as TRUE)
• links to: PR#360