[HBASE-2531] 32-bit encoding of regionnames waaaaaaayyyyy too susceptible to hash clashes

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 0.90.0
• Labels: moved_from_0_20_5
• Hadoop Flags: Reviewed
• Release Note: Changes format of region name. Adds an md5 suffix. Suffix is now the name used as directory name in filesystem.
• Assignee: Kannan Muthukkaruppan
• Reporter: Michael Stack
• Created: 11/May/10 05:30
• Updated: 21/Sep/23 08:40
• Resolved: 01/Jun/10 03:52

Description

Kannan tripped over two regionnames that hashed the same:

Here is code demo'ing that his two names hash the same:

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));
  }
}

Need new encoding mechanism. Will need to migrate old regions to new schema.

Issue Links

• relates to: HBASE-2600 Change how we do meta tables; from tablename+STARTROW+randomid to instead, tablename+ENDROW+randomid