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With the Data not shared model, how does a client or query get a consistent data and how does a write ensure that it is writing right data. Obvious answer is the maintaining consistency in a database involves in adhering the ACID Properties. Cassandra follows Atomicity, Isolation, Durability but consistency is an eventual consistency or […] 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 […] 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 […] 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 cassandraenv.sh MAX_HEAP_SIZE SGA is […] 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), […] 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 Apache.org or Datastax for an enterprise version. […] 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 […] As we all know Active Dataguard is a licensed feature and whilst there is no parameter to control, indeed if just in case if you do not have a license and by chance your DBA has opened the standby database in readonly and started MRP then you are in troubles as it activates the Active […] Consider a Typical Database Migration which contains all of this below (and if down time is not a problem) 1. Into a new Database Host (NEW SERVER) 2. Convert to Non-ASM to ASM 3. Convert to Single Instance to RAC, 4. Upgrade to Database to 12c Environment Details Source Target DB Version: […] Have got a question from one of fellow DBA that how much PGA the session will use or needed. Well to answer this, first we need to know what PGA looks like and what it used for? The follow shows the components of a PGA, the little space used for Stack, Env Variables and Private […] |
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Oracle 23c New Features for DBA's
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