[CALCITE-3300] In JDBC adapter, when generating SQL for count star, generates the star argument of the call

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.21.0
• Fix Version/s: 1.22.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Danny Chen
• Reporter: Wang Weidong
• Due: 28/Sep/19
• Created: 28/Aug/19 07:52
• Updated: 06/Mar/20 04:35
• Resolved: 23/Oct/19 09:02

Description

Procedure to reproduce the problem:

• create table _^t
• parse query  select count from t to SqlNode
• convert SqlNode to RelNode
• convert RelNode to SqlNode
• validate the result SqlNode

test code is like this

// code placeholder
@Test
public void testSelectCountAll() throws Exception {
  try (Statement s = parserContext.getStatement()) {
    s.execute("create table if not exists t (i int not null)");

    String sql = "select count(*) from t";
    SqlNode sqlNode = parserContext.parseStmt(sql);
    parserContext.getSqlValidator().validate(sqlNode);
    RelNode relNode = parserContext.getSqlToRelConverter().convertQuery(sqlNode, true, true).rel;
    SqlNode sqlNodeNew = toSqlNode(relNode);
    parserContext.getSqlValidator().validate(sqlNodeNew);
  }
}

Finally we will get an exception as follow:

// code placeholder
org.apache.calcite.runtime.CalciteContextException: At line 0, column 0: Invalid number of arguments to function 'COUNT'. Was expecting 1 argumentsorg.apache.calcite.runtime.CalciteContextException: At line 0, column 0: Invalid number of arguments to function 'COUNT'. Was expecting 1 arguments at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at org.apache.calcite.runtime.Resources$ExInstWithCause.ex(Resources.java:463) at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:783) at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:768) at org.apache.calcite.sql.validate.SqlValidatorImpl.newValidationError(SqlValidatorImpl.java:4753) at org.apache.calcite.sql.validate.SqlValidatorImpl.handleUnresolvedFunction(SqlValidatorImpl.java:1699) at org.apache.calcite.sql.SqlFunction.deriveType(SqlFunction.java:270) at org.apache.calcite.sql.SqlFunction.deriveType(SqlFunction.java:215) at org.apache.calcite.sql.fun.SqlCountAggFunction.deriveType(SqlCountAggFunction.java:83) at org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:5477) at org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:5464) at org.apache.calcite.sql.SqlCall.accept(SqlCall.java:138) at org.apache.calcite.sql.validate.SqlValidatorImpl.deriveTypeImpl(SqlValidatorImpl.java:1629) at org.apache.calcite.sql.validate.SqlValidatorImpl.deriveType(SqlValidatorImpl.java:1614) at org.apache.calcite.sql.validate.SqlValidatorImpl.expandSelectItem(SqlValidatorImpl.java:457) at org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelectList(SqlValidatorImpl.java:4017) at org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelect(SqlValidatorImpl.java:3280) at org.apache.calcite.sql.validate.SelectNamespace.validateImpl(SelectNamespace.java:60) at org.apache.calcite.sql.validate.AbstractNamespace.validate(AbstractNamespace.java:84) at org.apache.calcite.sql.validate.SqlValidatorImpl.validateNamespace(SqlValidatorImpl.java:967) at org.apache.calcite.sql.validate.SqlValidatorImpl.validateQuery(SqlValidatorImpl.java:943) at org.apache.calcite.sql.SqlSelect.validate(SqlSelect.java:225) at org.apache.calcite.sql.validate.SqlValidatorImpl.validateScopedExpression(SqlValidatorImpl.java:918) at org.apache.calcite.sql.validate.SqlValidatorImpl.validate(SqlValidatorImpl.java:628) at org.apache.calcite.test.OptimizeTest.testSelectCountAll(OptimizeTest.java:220) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.rules.ExpectedException$ExpectedExceptionStatement.evaluate(ExpectedException.java:239) at org.junit.rules.RunRules.evaluate(RunRules.java:20) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)Caused by: org.apache.calcite.sql.validate.SqlValidatorException: Invalid number of arguments to function 'COUNT'. Was expecting 1 arguments at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at org.apache.calcite.runtime.Resources$ExInstWithCause.ex(Resources.java:463) at org.apache.calcite.runtime.Resources$ExInst.ex(Resources.java:572) ... 47 more

 

After debugging, I found that the main causes of this exception are as follows.

First, while converting RelNode to SqlNode, in the method _{^{org.apache.calcite.rel.rel2sql.SqlImplementor.Context#toSql}}

https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/rel2sql/SqlImplementor.java#L869,

the operandList is empty because that there is with no argument in aggCall.

Second,  while validating  the result SqlNode, in the method  org.apache.calcite.sql.fun.SqlCountAggFunction#deriveType

https://github.com/apache/calcite/blob/8327e674e7f0a768d124fa37fd75cda4b8a35bb6/core/src/main/java/org/apache/calcite/sql/fun/SqlCountAggFunction.java#L79,

the result of function call call.isCountStar() is false, because there is no operand in call. While actually this is a count star call.

 

How to solve this problem?  

I think we can solve it either in the first or second step, but solving it in the second step is more appropriate because SqlNode converted from RelNode should be same with the result parsed from sql string possibly.

 

Issue Links

• links to: GitHub Pull Request #1422