Oracle Sharding distributes segments of a data set across many databases (shards) on different computers, either on-premises or in cloud. Sharding enables globally distributed, linearly scalable, multimodel databases. It requires no specialized hardware or software. Oracle Sharding does all this while rendering the strong consistency, full power of SQL, support for structured and unstructured data, and the Oracle Database ecosystem. It meets data sovereignty requirements, and supports applications that require low latency and high availability.
All of the shards together make up a single logical database, which is referred to as a sharded database (SDB).
Kubernetes provides infrastructure building blocks, such as compute, storage, and networks. Kubernetes makes the infrastructure available as code. It enables rapid provisioning of multi-node topolgies. Additionally, Kubernetes also provides statefulsets, which are the workload API objects that are used to manage stateful applications. This provides us lifecycle management elasticity for databases as a stateful application for various database topologies, such as sharded databases, Oracle Real Application Clusters (Oracle RAC), single instance Oracle Database, and other Oracle features and configurations.
The Sharding Database controller in Oracle Database Operator deploys Oracle Sharding topology as a statefulset in the Kubernetes clusters, using Oracle Database and Global Data Services Docker images. The Oracle Sharding database controller manages the typical lifecycle of Oracle Sharding topology in the Kubernetes cluster, as shown below:
- Create primary statefulsets shards
- Create master and standby Global Data Services statefulsets
- Create persistent storage, along with statefulset
- Create services
- Create load balancer service
- Provision sharding topology by creating and configuring the following:
- Catalog database
- Shard Databases
- GSMs
- Shard scale up and scale down
- Shard topology cleanup
The Oracle Sharding database controller provides end-to-end automation of Oracle Database sharding topology deployment in Kubernetes clusters.
To create a Sharding Topology, complete the steps in the following sections below:
- Prerequsites for running Oracle Sharding Database Controller
- Provisioning Sharding Topology in a Cloud based Kubernetes Cluster (OKE in this case)
- Connecting to Shard Databases
- Debugging and Troubleshooting
Note Before proceeding to the next section, you must complete the instructions given in each section, based on your enviornment, before proceeding to next section.
IMPORTANT : You must make the changes specified in this section before you proceed to the next section.
1. Kubernetes Cluster: To deploy Oracle Sharding database controller with Oracle Database Operator, you need a Kubernetes Cluster which can be one of the following:
- A Cloud-based Kubernetes cluster, such as OCI on Container Engine for Kubernetes (OKE) or
- An On-Premises Kubernetes Cluster, such as Oracle Linux Cloud Native Environment (OLCNE) cluster.
To use Oracle Sharding Database Controller, ensure that your system is provisioned with a supported Kubernetes release. Refer to the Release Status Section.
To deploy Oracle Database Operator in a Kubernetes cluster, go to the section Quick Install of the Operator in the README, and complete the operator deployment before you proceed further. If you have already deployed the operator, then proceed to the next section.
Choose one of the following deployment options:
Use Oracle-Supplied Docker Images: The Oracle Sharding Database controller uses Oracle Global Data Services and Oracle Database images to provision the sharding topology.
You can also download the pre-built Oracle Global Data Services container-registry.oracle.com/database/gsm:latest and Oracle Database images container-registry.oracle.com/database/enterprise:latest from Oracle Container Registry. These images are functionally tested and evaluated with various use cases of sharding topology by deploying on OKE and OLCNE.
OR
Build your own Oracle Database and Global Data Services Docker Images: You can build these images using instructions provided on Oracle official GitHub Repositories:
After the images are ready, push them to your Docker Images Repository, so that you can pull them during Oracle Database Sharding topology provisioning.
You can either download the images and push them to your Docker Images Repository, or, if your Kubernetes cluster can reach OCR, you can download these images directly from OCR.
Note: In the sharding example yaml files, we are using GDS and database images available on Oracle Container Registry.
Create a Kubernetes namespace named shns. All the resources belonging to the Oracle Database Sharding Setup will be provisioned in this namespace named shns. For example:
#### Create the namespace
kubectl create ns shns
#### Check the created namespace
kubectl get ns5. Create a Kubernetes secret for the database installation owner for the database Sharding Deployment
Create a Kubernetes secret named db-user-pass using these steps: Create Kubernetes Secret
After you have the above prerequsites completed, you can proceed to the next section for your environment to provision the Oracle Database Sharding Topology.
Deploy Oracle Database sharding topology on your Cloud based Kubernetes cluster. In this example, the deployment uses the YAML file based on OCI OKE cluster. There are multiple use case possible for deploying the Oracle Database sharding topology.
1. Provisioning Oracle Database sharding topology without Database Gold Image
2. Provisioning Oracle Database sharding topology with additional control on resources like Memory and CPU allocated to Pods
3. Provisioning a Persistent Volume having an Oracle Database Gold Image
4. Provisioning Oracle Database sharding topology by cloning database from your own Database Gold Image in the same Availability Domain(AD)
5. Provisioning Oracle Database sharding topology by cloning database from your own Database Gold Image across Availability Domains(ADs)
6. Provisioning Oracle Database sharding topology and send Notification using OCI Notification Service
7. Scale Out - Add Shards to an existing Oracle Database Sharding Topology
8. Scale In - Delete an existing Shard from a working Oracle Database sharding topology
After the Oracle Database Sharding Topology has been provisioned using the Sharding Controller in Oracle Database Kubernetes Operator, you can follow the steps in this document to connect to the Sharded Database or to the individual Shards: Database Connectivity
To debug the Oracle Database Sharding Topology provisioned using the Sharding Controller of Oracle Database Kubernetes Operator, follow this document: Debugging and troubleshooting