Hequn Cheng created CALCITE-2683:
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Summary: ProjectMergeRule should not be performed when
Nondeterministic udf has been referenced more than once
Key: CALCITE-2683
URL: https://issues.apache.org/jira/browse/CALCITE-2683
Project: Calcite
Issue Type: Bug
Components: core
Reporter: Hequn Cheng
Assignee: Hequn Cheng
Currently, there are some merge rules for project, such as {{CalcMergeRule}},
{{ProjectMergeRule}}, and {{ProjectCalcMergeRule}}. I found that these merge
rules should not be performed when Nondeterministic expression of the bottom
project has been referenced more than once by the top project. Take the
following test as an example:
{code:java}
@Test public void testProjectMergeCalcMergeWithNonDeterministic() throws
Exception {
HepProgram program = new HepProgramBuilder()
.addRuleInstance(FilterProjectTransposeRule.INSTANCE)
.addRuleInstance(ProjectMergeRule.INSTANCE)
.build();
checkPlanning(program,
"select name, a as a1, a as a2 from (\n"
+ " select *, rand() as a\n"
+ " from dept)\n"
+ "where deptno = 10\n");
}
{code}
The result plan is
{code:java}
LogicalProject(NAME=[$1], {color:red}A1{color}=[RAND()],
{color:red}A2{color}=[RAND()])
LogicalFilter(condition=[=($0, 10)])
LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
{code}
In the plan, {color:red}A1{color} may not equal to {color:red}A2{color} since
the two projects are merged which is against the SQL.
One option to solve the problem is to disable these merge rules in such cases.
What do you guys think? Any suggestions are greatly appreciated.
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