Moving Partitioned Region Data to Another Member

This topic explains how to move partitioned data from one member to another in VMware Tanzu GemFire.

You can use the PartitionRegionHelper moveBucketByKey and moveData methods to explicitly move partitioned region data from one member to another.

The moveBucketByKey method moves the bucket that contains the specified key from a source member to a destination member. For example, you could use the method to move a popular product item to a new, empty member to reduce load on the source member.

For example:

Object product = ...
Region r = ...
DistributedSystem ds = ...
String memberName = ...

//Find the member that is currently hosting the product.
Set<DistributedMember> sourceMembers =
PartitionRegionHelper.getAllMembersForKey(r, product);

//Find the member to move the product to.
DistributedMember destination = ds.findDistributedMember(memberName);

//In this example we assume there is always at least one source.
//In practice, you should check that at least one source
//for the data is available.
source = sourceMembers.iterator().next();

//Move the bucket to the new node. The bucket will
//be moved when this method completes. It throws an exception
//if there is a problem or invalid arguments.
PartitionRegionHelper.moveBucketByKey(r, source, destination, product);

See the Java API documentation for org.apache.geode.cache.partition.PartitionRegionHelper.moveBucketByKey for more details.

The moveData method moves data up to a given percentage (measured in bytes) from a source member to a destination member. For example, you could use this method to move a specified percentage of data from an overloaded member to another member to improve distribution.

For example:

Region r = ...
DistributedSystem ds = ...
String sourceName = ...
String destName = ...

//Find the source member.
DistributedMember source = ds.findDistributedMember(sourceName);
DistributedMember destination = ds.findDistributedMember(destName);

//Move up to 20% of the data from the source to the destination node.
PartitionRegionHelper.moveData(r, source, destination, 20);

See the Java API documentation for org.apache.geode.cache.partition.PartitionRegionHelper.moveData for more details.

For more information about partitioned regions and rebalancing, see Partitioned Regions.