[jira] [Updated] (IGNITE-13443) distributed left joins errored with "java.lang.ClassCastException"

["Isaac Zhu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-13443?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Isaac Zhu updated IGNITE-13443:
-------------------------------
    Component/s: sql

> distributed left joins errored with "java.lang.ClassCastException"
> ------------------------------------------------------------------
>
>                 Key: IGNITE-13443
>                 URL: https://issues.apache.org/jira/browse/IGNITE-13443
>             Project: Ignite
>          Issue Type: Bug
>          Components: h2-limitation, sql
>    Affects Versions: 2.8.1
>            Reporter: Isaac Zhu
>            Priority: Blocker
>         Attachments: JoinBatch.java
>
>
> This is actually an H2 1.4.197 Bug
> When using *distributed joins*, SQL like this (table A and table B are not collocated, so distributed join is used here):
>      select * from table A left join table B on A.id = B.id left join table C on B.id = C.id where ...
> has chance to error out at the second left join with a "java.lang.ClassCastException" when the first left join had an EmptyCursor
>  
> This is because, for distributed join, H2 JoinBatch is used - it seems JoinBatch is not used for collocated join.
> In JoinBatch line 292:
> [https://github.com/h2database/h2database/blob/c8a861bb1a3f04967ec40cb5e3336535c43af5fb/h2/src/main/org/h2/table/JoinBatch.java#L292]
> It increases the filter ID to let the next fetchCurrent call resolve the "EMPTY_CURSOR" to a NullRow when a "JoinFilter.find" is not called.
> Then, in the "find" call, the resolved NullRow will be updated to some cursor from the future - because only EmptyCursor is skipped in the find(), a NullRow will be updated again and the bitwise state goes wrong
> This then causes the exception in "fetchCurrent" line:  358
> [https://github.com/h2database/h2database/blob/c8a861bb1a3f04967ec40cb5e3336535c43af5fb/h2/src/main/org/h2/table/JoinBatch.java#L358]
> The "x" is a Future, so it can't be cast to a Cursor - the state is wrong, the "isFuture" returns false while it is a Future.
>  
> I did a local fix in our server as a workaround in org.h2.table.JoinBatch, the changed code is attached.
>  



--
This message was sent by Atlassian Jira
(v8.3.4#803005)