[GitHub] [shardingsphere] tristaZero edited a comment on issue #8284: [New feature] Federated SQL query and Query optimization are going to sail out.

[GitBox <gi...@apache.org>]

tristaZero edited a comment on issue #8284:
URL: https://github.com/apache/shardingsphere/issues/8284#issuecomment-737131692


   My greetings for @junwen12221 @guimingyue .
   
   
   Based on the points @junwen12221 gave before, I write a [demo](https://github.com/tristaZero/federatedSQL) for this issue, i.e., SQL federation and SQL query optimization.
   
   In this demo, SQL federation using Calcite JDBC driver can work well. Nonetheless,  I also write a raw executor (As 3 mentioned above) with parsing, validating, optimizing and executing, which you can view as a custom executor driver. Supposing this custom executor driver has a run-through process, we can replace Calcite parser with our SQL parser and add more plan rules to `findBestExp`.
   
   Unfortunately, this `CalciteRawExecutor` succeeded in parsing, validating, optimizing SQLs but is blocked in executing. :( 
   
   I tried any method I can, but failed, so I sincerely seek your any kind help and point! The exception info is presented later, also you can run `assertSingleExecute()` in `CalciteRawExecutorTest` to make it recurred.
   
   The reason, I guess, is related to [using the custom schema](https://github.com/tristaZero/federatedSQL/blob/ce71c8fa6e7b09e7d11dce660980c3a9922e1a97/src/main/java/federated/sql/executor/CalciteRawExecutor.java#L95) since it is different from [this example new ReflectiveSchema()](https://github.com/zabetak/calcite/blob/c7646fa6d3054b9e6b9a800e08d18f3cc89922e4/core/src/test/java/org/apache/calcite/examples/foodmart/java/EndToEndExampleEnumerable.java#L117). But I have no approaches to debug or figure out the corresponding solutions. 
   
   ```java
   15:01:08.019 [main] DEBUG org.apache.calcite.plan.RelOptPlanner - Provenance:
   rel#19:EnumerableCalc.ENUMERABLE(input=EnumerableCalc#18,expr#0..2={inputs},0=$t0)
     direct
       rel#17:EnumerableCalc.ENUMERABLE(input=RelSubset#16,expr#0..2={inputs},0=$t0)
         call#9 rule [EnumerableCalcRule(in:NONE,out:ENUMERABLE)]
           rel#14:LogicalCalc.NONE(input=RelSubset#6,expr#0..2={inputs},0=$t0)
             call#5 rule [ProjectToCalcRule]
               rel#7:LogicalProject.NONE(input=RelSubset#6,inputs=0)
                 no parent
   rel#18:EnumerableCalc.ENUMERABLE(input=EnumerableTableScan#11,expr#0..2={inputs},expr#3=10,expr#4=<($t0, $t3),proj#0..2={exprs},$condition=$t4)
     direct
       rel#15:EnumerableCalc.ENUMERABLE(input=RelSubset#12,expr#0..2={inputs},expr#3=10,expr#4=<($t0, $t3),proj#0..2={exprs},$condition=$t4)
         call#7 rule [EnumerableCalcRule(in:NONE,out:ENUMERABLE)]
           rel#13:LogicalCalc.NONE(input=RelSubset#4,expr#0..2={inputs},expr#3=10,expr#4=<($t0, $t3),proj#0..2={exprs},$condition=$t4)
             call#3 rule [FilterToCalcRule]
               rel#5:LogicalFilter.NONE(input=RelSubset#4,condition=<($0, 10))
                 no parent
   rel#11:EnumerableTableScan.ENUMERABLE(table=[sharding, t_order])
     call#1 rule [EnumerableTableScanRule(in:NONE,out:ENUMERABLE)]
       rel#1:LogicalTableScan.NONE(table=[sharding, t_order])
         no parent
   
   
   java.lang.NullPointerException
   	at Baz.bind(Unknown Source)
   	at federated.sql.executor.CalciteRawExecutor.execute(CalciteRawExecutor.java:184)
   	at federated.sql.executor.CalciteRawExecutor.execute(CalciteRawExecutor.java:173)
   	at federated.sql.executor.CalciteRawExecutorTest.assertSingleExecute(CalciteRawExecutorTest.java:61)
   	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.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
   	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$2.evaluate(ParentRunner.java:268)
   	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
   	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
   	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
   	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
   	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
   	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
   ```
   


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