The I/O performed by most OLTP systems tends to beapproximately 70–80 percent read and 20–30 percent write.
Business intelligence data warehousing systems and OLTP systems could accessmuch of the same data, but these types of systems also typically have differentrequirements in terms of CPU, memory, and data layout, which makes supporting amixed workload less than optimal for both types of processing.
Real ApplicationClusters, with dynamic service provisioning since Oracle Database 10g, makes it possibleto allocate individual nodes for individual workloads.
Oracle7 introduced stored procedures written in PL/SQL, Oracle’s proprietary languagefor writing application logic. These procedures are stored in the database andexecuted by clients issuing remote procedure calls (RPCs) as opposed to executingSQL statements. Instead of issuing multiple SQL calls, occasionally with intermediatelogic to accomplish a task, the client issues one procedure call, passing in therequired parameters. The database executes all the required SQL and logic using theparameters it receives.
If the database server failswhile executing some transaction, the application server can resubmit the transactionto a surviving database server, as control of the transaction lies with theapplication server.