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12c Upgrade Gotchas

The following are various gotchas during upgrade or post upgrade to 12c collect from various sources and also few of them in my environment.

1. Change of resource_limit parameter to true by default

Impact: Resource Manager will be invoked automatically and push the resource limits to the sessions and users may receive cpu/io restriction […]

Cassandra for Oracle DBA’s Part 4 – Data Distribution across Nodes

Shared Disk architecture in RAC where the data is shared across the nodes and at any point of time , every instance will give the same data using cache fusion.

But in Cassandra, the important part is storage is not shared storage, instead its sharded means partitioned and stored in each node.

And when […]

Cassandra for Oracle DBA’s Part 3 – Architecture

In Oracle (infact for any RDBMS) , will have a memory structures and processes (or thread) to process the data.

If we take Oracle as an example, lets look the similarities

1. Memory Architecture

Oracle Cassandra (NO-SQL DB) Parameter to Set in Cassandra.yaml file Comments SGA Java Heap Memory


SGA is […]

Cassandra for Oracle DBA’s Part 2 – Three things you need to know

Cassandra has three important differences if compared with RDBMS,

NO-SQL Data Stored as Columnar Structure Distributed Systems with Nothing Shared Architecture

Cassandra is combination of the Distributed Processing Systems (for high availability and scalability) with NO-SQL (to process unstructured data & schema less structure) & with Column Store(to store wide variety and velocity of data), […]

Cassandra for Oracle DBA’s Part 6 – Installing Cassandra

Installing Cassandra is straight forward, With CCM, is a tool to simulate a Cassandra cluster in a single host, Ideal for test environments or you want to make your hands on in Cassandra.

Further to install Cassandra in production size, you can directly download the Cassandra from or Datastax for an enterprise version.


Cassandra for Oracle DBA’s – Part 1 : Nomenclature or Commands or Features Comparision

Although, there are heaps of fundamental changes between Oracle & Cassandra,

Just for fun, or for nomenclature or for commands or similar features are listed here , which may provide handy information to Oracle DBA’s

Oracle Keyword Cassandra Feature / Nomenclature SGA Java Heap Memory Buffer Cache Memtables LRU List Parition Index Summary Cache […]