Information Lifecycle Management (ILM) is the practice of applying policies for the effective management of information throughout its useful life. Implementing ILM become more beneficial in data warehouse environments, where we are required to keep historical data. Data Warehouse databases can grow exponentially and It makes complete sense to move data to different storage tier though its life cycle to save cost and availability.
Benefits of implementing ILM
- Works at the database level with no application changes
- Reduces disk space requirements for all types of data
- Allows you to automate the movement of data to lower-cost storage based on activity patterns
- Lowers query times by keeping only active data on high performance storage
- Increases availability of critical information on the most reliable storage
How Implement ILM using Oracle database features
- Use Oracle ADO to create policies for data compression and data movement between different compression level and different tiers of storage.
- Use Oracle 12c feature Heat Map to track data usage
- Use Table Partitioning to move historical data to low performance storage tier
- Use Advance / HCC compression to compress historical data to same or low cost storage tier
Note : Oracle 12c introduce 2 new feature call Automatic Data Optimization (ADO) and Heat Map, Both features are part of Oracle Advance Compression Option.
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Building Operational Data Store on Oracle Exadata
What is Oracle RAC
Oracle RAC is a cluster technology which provide database high availability. It’s a hardware configuration where multiple interconnected servers appear as one to end users and applications, Oracle RAC is a complex topic, I will try to keep it simple and focus on OBIEE connection, query execution and High availability.
Query Execution in RAC Database
In this section, I will explain how Oracle RAC handle queries from OBIEE. If query is running in NOPARALLEL mode, it will only run on one of Oracle RAC instance. But If query is running in parallel mode, it can run 1 or multiple instances. It depend on database parameter setting called PARALLEL_FORCE_LOCAL (true or false).
With 11gr2 Oracle introduces a new feature called In-Memory Parallel Execution, which leverages shared memory cache (SGA) . Oracle uses the aggregated memory cache of all the servers in a Real Application Clusters (RAC) environment to deterministically cache objects distributed across the memory of all nodes. This ensures that subsequent parallel queries will read data out of cache from all nodes that can speed up processing times enormously instead of reading data from storage.
High Availability with Oracle RAC
It is best practice to use services to connect Oracle RAC databases. Services enable you to group database workloads and route work to the optimal instances that are assigned to offer the service. Services make the work load more manageable, measurable, tunable and recoverable. You services to connect one or more instances to for load balancing. In a nut shell Oracle RAC will distribute OBIEE connection evenly to multiple instances. you can configure services to run on multiple node simultaneously or one instance at time (failover to second instance if node fails).
Example: Creating Services
srvctl add service -s OBIEE_CONNECTION –a Node1 –r Node2 -d RACDB
srvctl add service -s OBIEE_CONNECTION –a Node1, Node2 -d RACDB
Example: Connection String