[jira] [Work logged] (HIVE-27157) AssertionError when inferring return type for unix_timestamp function

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-27157?focusedWorklogId=852051&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-852051 ]

ASF GitHub Bot logged work on HIVE-27157:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 21/Mar/23 15:59
            Start Date: 21/Mar/23 15:59
    Worklog Time Spent: 10m 
      Work Description: zabetak opened a new pull request, #4135:
URL: https://github.com/apache/hive/pull/4135

   ### What changes were proposed in this pull request?
   Change the implementation of unix_timestamp operators to avoid the AssertionError and infer the return type correctly; always BIGINT.
   
   Break the inheritance relation with SqlAbstractTimeFunction and change the SqlFunctionCategory from TIMEDATE to NUMERIC; unix_timestamp is not a time function since the result is never among DATE, TIME, or TIMESTAMP.
   
   Change the operand type checker to a more truthful implementation; the type checker is not really used at the moment but it is better to have something realistic there instead of null or something completely wrong.
   
   ### Why are the changes needed?
   Calls to `inferReturnType` method for `unix_timestamp` operators always lead to `AssertionError`.
   
   Contrary to operand type checking and operand type inference that are not really relevant for Hive (the latter is not using the `SqlValidator` logic), the return type inference is important since it may kick in some calls to `RelBuilder/RexBuilder` APIs. Such calls exist in older versions of Hive and are widely used in Calcite's built-in rules.
   
   ### Does this PR introduce _any_ user-facing change?
   In this version no, but in older versions of Hive it can fix queries failing with `AssertionError`.
   
   ### How was this patch tested?
   ```
   mvn test -Dtest=TestSqlOperatorInferReturnType
   ```




Issue Time Tracking
-------------------

            Worklog Id:     (was: 852051)
    Remaining Estimate: 0h
            Time Spent: 10m

> AssertionError when inferring return type for unix_timestamp function
> ---------------------------------------------------------------------
>
>                 Key: HIVE-27157
>                 URL: https://issues.apache.org/jira/browse/HIVE-27157
>             Project: Hive
>          Issue Type: Bug
>          Components: CBO
>    Affects Versions: 4.0.0-alpha-2
>            Reporter: Stamatis Zampetakis
>            Assignee: Stamatis Zampetakis
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Any attempt to derive the return data type for the {{unix_timestamp}} function results into the following assertion error.
> {noformat}
> java.lang.AssertionError: typeName.allowsPrecScale(true, false): BIGINT
> 	at org.apache.calcite.sql.type.BasicSqlType.checkPrecScale(BasicSqlType.java:65)
> 	at org.apache.calcite.sql.type.BasicSqlType.<init>(BasicSqlType.java:81)
> 	at org.apache.calcite.sql.type.SqlTypeFactoryImpl.createSqlType(SqlTypeFactoryImpl.java:67)
> 	at org.apache.calcite.sql.fun.SqlAbstractTimeFunction.inferReturnType(SqlAbstractTimeFunction.java:78)
> 	at org.apache.calcite.rex.RexBuilder.deriveReturnType(RexBuilder.java:278)
> {noformat}
> due to a faulty implementation of type inference for the respective operators:
>  * [https://github.com/apache/hive/blob/52360151dc43904217e812efde1069d6225e9570/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/reloperators/HiveUnixTimestampSqlOperator.java]
>  * [https://github.com/apache/hive/blob/52360151dc43904217e812efde1069d6225e9570/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/reloperators/HiveToUnixTimestampSqlOperator.java]
> Although at this stage in master it is not possible to reproduce the problem with an actual SQL query the buggy implementation must be fixed since slight changes in the code/CBO rules may lead to methods relying on {{{}SqlOperator.inferReturnType{}}}.
> Note that in older versions of Hive it is possible to hit the AssertionError in various ways. For example in Hive 3.1.3 (and older), the error may come from [HiveRelDecorrelator|https://github.com/apache/hive/blob/4df4d75bf1e16fe0af75aad0b4179c34c07fc975/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveRelDecorrelator.java#L1933] in the presence of sub-queries.



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