The article explains the detailed characteristics of Oracle Parallel operation execution. There are lots of benefits of Parallel execution but with some drawbacks in the Oracle Database Server.
Any operation doesn’t consume or utilize the whole server resources at any time. The reason behind this whole work is performing by a single server process in the database. This means if we have more resources like more CPU then a little bit of resource of CPU is consumed by the server process during the whole operation. In short, we can say that we are not utilizing full server resources at any time. There are two types of operations available in the Oracle database server. The first one is called Serial operation which is the default behavior of the Oracle server. The single server process fetches data or performs operation serially. This kind of operation doesn’t consume more resources from the Oracle server. The serial operation can be not effective when large table objects or large operations. The performance of the operation will be degrading. During this serial operation, the Oracle server doesn’t consume full server resources. The second operation called a parallel operation. During parallel operation more than single threads are performing operation simultaneously. Due to this reason full server resource utilized and providing result very quickly. The parallel process is more effective for large Oracle databases. The performance of the Oracle server will be upgrading whenever using parallel operation. One server process is controlling parallel threads and it will verify how the tasks required for the procedure are to be assigned.
Once processing of data finished then Oracle server process is gathering data serially and returning output. Hence we can say that in the parallel process both operations are involving parallel and serial.
This is the same concept of our mathematics one man finishes work within 2 hours then more than 1 man will finish the same work 2 hours/number of man. 2 men can finish the same work within 1 hour and 4 men can finish the same work within 30 min. When we are talking about 1 man finish it is the serial operation and more than 1 man, it parallel operation.
We can’t say that the parallel process is always faster than serial operation in Oracle Database Server. Sometimes the parallel operation is not more effective and not able to provide results as per requirement. We have seen that every server process has some child processes in parallel execution. Sometimes lack of memory child processes is not performing a good task. Allocation of process are may be fully utilized by other processes. It also raises a related point that the finest point for one parallel operation may not actually be the best level for numerous operations on an Oracle server system in which all the processes are trying to run in parallel. In short, we can say, the resources consumed by adding additional parallel processes up to a certain point where the operation finishes the quickest may be comparatively greater than the supplementary performance improvement. Therefore, reducing the number of child processes to a level below where the operation would finish the fastest method essentially offers the most advantage to the Oracle server. Before enabling parallel execution operation we should need to understand our Oracle server system. If you don’t know the Oracle server resources and characteristics then instead of improving the performance of the Oracle database it would be degrading performance of Oracle server.
This means we can say that usage of parallel execution may not provide a guarantee to improve the performance of the Oracle database, but sometimes it also risk to degrade the performance of the Oracle server. Parallel operation is more usable in large databases, high-end servers, more CPU resources, and optimized SQL coding. Without knowing these all things if we are enabling a parallel option maybe provide us a negative impact on the performance of the server.
The partition table is more helpful to improve performance while using parallel execution. Partition table with more CPU is more target to increase the scalability of the database with parallel operations.
Oracle improves parallel operation usage in its own new features like RMAN, Parallel recovery, SQL Loader, EXPDP, IMPDP, etc. Export doesn’t has parallel feature but datapump (expdp) has parallel execution feature in Oracle 10g. Rman is becoming more faster while using a parallel feature for backup.
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Expert Remote DBA team – Dbametrix Solutions