How to understand the parallel operation of Oracle

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SQL statements are serialized on one cpu by default, and even if the system has multiple cpu, they cannot be used, so an obvious bottleneck is a

The resources used by cpu determine the performance of sql statements.

So it comes out of the situation and operates in parallel-- working with multiple cpu at the same time.

There are two processes for parallel operations:

Slave Process: this type of process is made up of multiple processes with the same status. Each process is responsible for part of or a unit of work. For example, full table scan, each process is responsible

Scan part of the segment, such a set of processes is also called a PS Set.

Query Coodinator: these processes are basically processes that issue sql statements, which are responsible for breaking a task into multiple task slices and applying for PS Set.

Determine the content of its work, and collect the processing results of each PS Set, and finally summarize and return the results.

Give several examples of parallel operations.

This is a statement-level parallel operation that we often use in practice:

`

Insert into / * + parallel (text1 4) * / text1 select * from v$session

`

Parallel operations can be more efficient when cpu is rich, but it can be self-defeating on some poor-performing servers.

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