PX BLOCK ITERATOR
Short Description
The PX BLOCK ITERATOR row source represents the splitting up of the table into pieces to divide the scan workload between the parallel execution servers.
Detailed Description​
Partitioning is typically used on very large tables and use of the partition keys can allow targeted access to a reduced data set - remember - to make a query go faster - access less data. Partitioned tables can be accessed using parallel query servers. Parallel query servers are great at returning data fast, but be aware of the CPU and disk resource usage as in a multi user system, resources can be exhausted very quickly.
Further Reading​
- Oracle Magazine - How to read an execution plan
- Oracle Tuning Guide - Explaining and Displaying Execution Plans
- Oracle Tuning Guide - Comparing Execution Plans Tutorial
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