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From "Jonathan Hsieh (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-3432) [hbck] Add "remove table" switch
Date Thu, 19 Jul 2012 23:30:35 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13418792#comment-13418792

Jonathan Hsieh commented on HBASE-3432:

[juneng603] eventually, after region assignments are completed and the region is opened on
the target RS, information is updated in the META table so that other clients can go to the
proper RS.
> [hbck] Add "remove table" switch
> --------------------------------
>                 Key: HBASE-3432
>                 URL: https://issues.apache.org/jira/browse/HBASE-3432
>             Project: HBase
>          Issue Type: New Feature
>          Components: util
>    Affects Versions: 0.89.20100924
>            Reporter: Lars George
>            Priority: Minor
> This happened before and I am not sure how the new Master improves on it (this stuff
is only available between the lines are buried in some peoples heads - one other thing I wish
was for a better place to communicate what each path improves). Just so we do not miss it,
there is an issue that sometimes disabling large tables simply times out and the table gets
stuck in limbo. 
> From the CDH User list:
> {quote}
> On Fri, Jan 7, 2011 at 1:57 PM, Sean Sechrist <ssechrist@gmail.com> wrote:
> To get them out of META, you can just scan '.META.' for that table name, and delete those
rows. We had to do that a few months ago.
> -Sean
> That did it.  For the benefit of others, here's code.  Beware the literal table names,
run at your own peril.
> {quote}
> {code}
> import java.io.IOException;
> import org.apache.hadoop.conf.Configuration;
> import org.apache.hadoop.hbase.HBaseConfiguration;
> import org.apache.hadoop.hbase.client.HTable;
> import org.apache.hadoop.hbase.client.Delete;
> import org.apache.hadoop.hbase.client.Result;
> import org.apache.hadoop.hbase.client.MetaScanner;
> import org.apache.hadoop.hbase.util.Bytes;
> public class CleanFromMeta {
>     public static class Cleaner implements MetaScanner.MetaScannerVisitor {
>         public HTable meta = null;
>         public Cleaner(Configuration conf) throws IOException {
>             meta = new HTable(conf, ".META.");
>         }
>         public boolean processRow(Result rowResult) throws IOException {
>             String r = new String(rowResult.getRow());
>             if (r.startsWith("webtable,")) {
>                 meta.delete(new Delete(rowResult.getRow()));
>                 System.out.println("Deleting row " + rowResult);
>             }
>             return true;
>         }
>     }
>     public static void main(String[] args) throws Exception {
>         String tname = ".META.";
>         Configuration conf = HBaseConfiguration.create();
>         MetaScanner.metaScan(conf, new Cleaner(conf), 
>              Bytes.toBytes("webtable"));
>     }
> }
> {code}
> I suggest to move this into HBaseFsck. I do not like personally to have these JRuby scripts
floating around that may or may not help. This should be available if a user gets stuck and
knows what he is doing (they can delete from .META. anyways). Maybe a "\-\-disable-table <tablename>
\-\-force" or so? But since disable is already in the shell we could add an "\-\-force" there?
Or add a "\-\-delete-table <tablename>" to the hbck?

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