PGDGroup parting v1
Deletion and finalizers
When deleting a PGD Group, the operator will start parting every node in the group first.
It will connect to an active instance and part every node in the target group.
Once a node is parted, it will not participate in replication and consensus operations.
To make sure the node is correctly parted before being deleted, the operator uses the
k8s.pgd.enterprisedb.io/partNodes finalizer. Please refer to the
kubernetes document on finalizers
for context.
Note
If a namespace holding a PGD Group is deleted directly, we can't ensure the deleting and parting sequence is carried out correctly. Before deleting a namespace, it is recommended to delete all the contained PGD groups.
Time limit
When parting a node, the operator needs to connect to an active instance to
execute the bdr.part_node function. To avoid this operation hanging,
a time limit for the finalizer is used; by default, it is 300 seconds.
After the time limit expires, the finalizer will be removed, and the node
will be deleted anyway, potentially leaving stale metadata in the global PGD catalog.
This time limit can be configured through spec.failingFinalizerTimeLimitSeconds,
which is specified in seconds.
Skip finalizer
For testing purposes only, the operator also provides an annotation to skip the
finalizer: k8s.pgd.enterprisedb.io/noFinalizers.
When this annotation is added to a PGDGroup, the finalizer will be skipped when
the PGDGroup is being deleted, and the nodes will not be parted from the PGD cluster.
PGDGroup cleanup
Cleanup parted node
Once the PGDGroup is deleted, its metadata will remain in the catalog in PARTED
state in the bdr.node_summary table. The PGD4K operator
defines a CRD named PGDGroupCleanup to help clean up the PARTED PGDGroup.
In the example below, the PGDGroupCleanup executes locally from region-a,
and will clean up all of region-b, with the pre-requisite that all the nodes must be
in the PARTED state.
apiVersion: pgd.k8s.enterprisedb.io/v1beta1 kind: PGDGroupCleanup metadata: name: region-b-cleanup spec: executor: region-a target: region-b
Please note that if the target group (region-b in the example) contains nodes
not in a PARTED state, the Group Cleanup will stop in phase
PGDGroupCleanup - Target PGDGroup is not parted, waiting for it to be parted before executing PGDGroupCleanup.
In cases of extreme need, we can add the force option.
Warning
Using force can leave the PGD cluster in an inconsistent state. Use it only to
recover from failures in which you can't part the group nodes any other way.
apiVersion: pgd.k8s.enterprisedb.io/v1beta1 kind: PGDGroupCleanup metadata: name: region-b-cleanup spec: force: true executor: region-a target: region-b