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https://issues.apache.org/jira/browse/HBASE-2531?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12866351#action_12866351
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Kannan Muthukkaruppan commented on HBASE-2531:
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Literature online seems to suggest that version 1 (timestamp based UUIDs) are
unique for all practical purposes. [Also read that <<If two UUIDs are
generated in sequence fast enough that the timestamp matches the previous UUID,
the timestamp is incremented by 1.>>].
Some references:
http://stackoverflow.com/questions/703035/when-are-you-truly-forced-to-use-uuid-as-part-of-the-design
http://blogs.msdn.com/oldnewthing/archive/2008/06/27/8659071.aspx
Re: migration, in a ZK based approach, wouldn't moving the pre-existing list of
encoded region names to ZK require some work?
For UUID based approach, it seems like there shouldn't really be any migration
work. Stack: can you confirm?
I
> 32-bit encoding of regionnames waaaaaaayyyyy too susceptible to hash clashes
> ----------------------------------------------------------------------------
>
> Key: HBASE-2531
> URL: https://issues.apache.org/jira/browse/HBASE-2531
> Project: Hadoop HBase
> Issue Type: Bug
> Reporter: stack
> Assignee: stack
> Priority: Blocker
> Fix For: 0.20.5, 0.21.0
>
>
> Kannan tripped over two regionnames that hashed the same:
> Here is code demo'ing that his two names hash the same:
> {code}
> package org;
> import org.apache.hadoop.hbase.util.Bytes;
> import org.apache.hadoop.hbase.util.JenkinsHash;
> public class Testing {
> public static void main(final String [] args) {
>
> System.out.println(encodeRegionName(Bytes.toBytes("test1,6838000000,1273541236167")));
>
> System.out.println(encodeRegionName(Bytes.toBytes("test1,0520100000,1273541610201")));
> }
> /**
> * @param regionName
> * @return the encodedName
> */
> public static int encodeRegionName(final byte [] regionName) {
> return Math.abs(JenkinsHash.getInstance().hash(regionName,
> regionName.length, 0));
> }
> }
> {code}
> Need new encoding mechanism. Will need to migrate old regions to new schema.
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