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https://issues.apache.org/jira/browse/IMPALA-10965?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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changxin reassigned IMPALA-10965:
---------------------------------
Assignee: changxin
> Show Crate Table XXX may throw an null pointer exception
> --------------------------------------------------------
>
> Key: IMPALA-10965
> URL: https://issues.apache.org/jira/browse/IMPALA-10965
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Reporter: changxin
> Assignee: changxin
> Priority: Minor
> Attachments: image-2021-10-12-17-12-48-035.png
>
>
>
> !image-2021-10-12-17-12-48-035.png!
> In my test environment, some SQL is running concurrently, but sometimes the
> "show create table xxx" statement will report a null pointer error, and the
> stack information is as shown in the figure above.
>
> After I checked, I found that the "show create table xxx" statement would get
> the metadata of the table before Analyze, and then it would run to
> org.apache.impala.service.JniFrontend.showCreateTable. Between these two
> operation, if the "invalidate metadata" statement is executed successfully,
> the cache in ImpaladCatalog will be deleted, and the table obtained in the
> showCreateTable function is the IncompleteTable type, then the above null
> pointer error will be reported in ToSqlUtils.getCreateTableSql.
>
> There are two ways to reproduce:
> 1. Frequently execute the "show create table xxx" and "invalidate metadata"
> statements at the same time.
> 2. Modify the showCreateTable code to sleep for a period of time before
> getting the table. Then executing the "show create table xxx" and "invalidate
> metadata" statements at the same time, due to sleep for a period of time, the
> probability of the problem will greatly increase.
>
> I think we should add a judgment of "table instanceof IncompleteTable" in
> showCreateTable, and report the error that the metadata may have been deleted
> instead of reporting a null pointer.
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