[jira] [Commented] (ACCUMULO-335) Batch scanning over the !METADATA table can cause issues

["Keith Turner (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-335?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13564705#comment-13564705 ] 

Keith Turner commented on ACCUMULO-335:
---------------------------------------

An exception like the following will show up in 1.4 when you run into this issue.  

{noformat}
root@test14> grep -t !METADATA -nt 1 time
28 16:25:45,753 [impl.TabletServerBatchReaderIterator] WARN : multiple extent types not allowed METADATA ROOT
java.lang.IllegalArgumentException: multiple extent types not allowed METADATA ROOT
	at org.apache.accumulo.core.client.impl.TabletType.type(TabletType.java:45)
	at org.apache.accumulo.core.client.impl.TabletServerBatchReaderIterator.doLookup(TabletServerBatchReaderIterator.java:537)
	at org.apache.accumulo.core.client.impl.TabletServerBatchReaderIterator$QueryTask.run(TabletServerBatchReaderIterator.java:338)
	at org.apache.accumulo.cloudtrace.instrument.TraceRunnable.run(TraceRunnable.java:47)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:662)
{noformat}

A workaround is to scan the root tablet and metadata tablets separately as follows :

{noformat}
root@test14> grep -t !METADATA -e !0< time
!0;~ srv:time []    L3
!0< srv:time []    L0
root@test14> grep -t !METADATA -b 0 time
1< srv:time []    M0
{noformat}

                
> Batch scanning over the !METADATA table can cause issues
> --------------------------------------------------------
>
>                 Key: ACCUMULO-335
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-335
>             Project: Accumulo
>          Issue Type: Bug
>          Components: client, tserver
>    Affects Versions: 1.4.0
>            Reporter: John Vines
>            Assignee: Keith Turner
>
> If you batch scan over the !METADATA table and have a tserver hosting both the root tablet and a metadata tablet, then you you will get an error. The quick fix is to specify a range. We should fix this in the long term. Perhaps this is a good reason to finally split the root tablet into it's own table?

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