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https://issues.apache.org/jira/browse/HBASE-2531?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12873745#action_12873745
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stack commented on HBASE-2531:
------------------------------
I tried it. I saw stuff like this:
{code}
2010-05-31 11:19:10,258 INFO org.apache.hadoop.hbase.master.ServerManager:
Processing MSG_REPORT_SPLIT_INCLUDES_DAUGHTERS:
TestTable,0010151443,1275329539809(717050107): Daughters;
TestTable,0010151443,1275329944907/80f60878ba8994c3458931a127d77377/,
TestTable,0010376061,1275329944907/9058243430462cd436fc06b748c0aaca/ from
sv2borg187,60020,1275329765174; 1 of 1
{code}
That looks really good as does a scan of .META. (I can see parents and
daughters.... we should get rid of the new-style encoded field in HRegionInfo,
but we can do that later).
Since there are so few things to change -- and changing the separator I can do
-- you want me to fix the above white-spacing, etc., issues on commit Kannan;
IOW, you don't have to make a new patch?
Looks great Kannan.
> 32-bit encoding of regionnames waaaaaaayyyyy too susceptible to hash clashes
> ----------------------------------------------------------------------------
>
> Key: HBASE-2531
> URL: https://issues.apache.org/jira/browse/HBASE-2531
> Project: HBase
> Issue Type: Bug
> Reporter: stack
> Assignee: Kannan Muthukkaruppan
> Priority: Blocker
> Fix For: 0.21.0
>
> Attachments: HBASE-2531_v2.patch
>
>
> 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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