This is the source-only release of the Apache Trafodion (incubating) project. This release provides support for HBase 0.98 and many new product features.
Build instructions are available here.
The following platforms are supported in this release.
|CentOS 6.5 – 6.7
|Cloudera CDH distribution 5.1 and Hortonworks distribution HDP 2.1
|JDK 1.7.0_67 or newer
This release contains the following new features.
|Infrastructure and High Availability
|Database and Query Performance
|Database Movement and Connectivity
This release contains fixes to 140 defects. Those defects were filed through Launchpad.
Getting TM error 97 when tables split or get moved
Symptom: HBase Region Splits, Load Balancing, and Error 97.
Cause: As part of an HBase environment’s ongoing operations (and based on the policies configured for the HBase environment), an HBase region can either get split (into two daughter regions) or moved to a different region server. (Please see the blog: http://hortonworks.com/blog/apache-hbase-region-splitting-and-merging/.) If that happens when a Trafodion transaction is active (and operates on rows within the region that is being split or load-balanced), then a subsequent transaction commit operation by the application might encounter an error 97. Please note that under such conditions the Trafodion Transaction Manager will abort the transaction and will preserve the integrity of the database.
Solution: To minimize disruptions when this happens, we suggest that you use one or more of the following approaches:
- Enhance your JDBC application logic to retry when an error 97 is returned for a commit operation.
- Update the HBase configuration to reduce the times when such disruptions happen. It involves updates to some properties that can be set in hbase-site.xml (or via the manageability interface of your Hadoop distribution).
- Set the maximum file size of an HBase Region to 100 GB. For example, set the value of the property hbase.hregion.max.filesize to 107374182400.
Set the HBase region split policy to 'ConstantSizeRegionSplitPolicy'. For example, set the value of the property hbase.regionserver.region.split.policy to org.apache.hadoop.hbase.regionserver.ConstantSizeRegionSplitPolicy.
NOTE: The split policy should already be set to 'onstantSizeRegionSplitPolicy' by the Trafodion installer.
Property Value hbase.hregion.max.filesize 107374182400 hbase.regionserver.region.split.policy org.apache.hadoop.hbase.regionserver.ConstantSizeRegionSplitPolicy
Disable HBase Region Load Balancing. Use the HBase shell command balance_switch false to disable the movement of a region from one server to another.
hbase shell hbase(main):002:0> balance_switch false true -- Output will be the last setting of the balance_switch value 0 row(s) in 0.0080 seconds
- Pre-split the table into multiple regions by using the SALT USING n PARTITIONS clause when creating the table. The number of partitions that you specify could be a function of the number of region servers present in the HBase cluster. Here is a simple example in which the table INVENTORY is pre-split into four regions when created:
CREATE TABLE INVENTORY ( ITEM_ID INT UNSIGNED NO DEFAULT NOT NULL , ITEM_TYPE INT UNSIGNED NO DEFAULT NOT NULL , ITEM_COUNT INT UNSIGNED NO DEFAULT NOT NULL , PRIMARY KEY (ITEM_ID ASC) ) SALT USING 4 PARTITIONS ;