Oracle Partitions.

MIHIR KAR used Ask the Experts™
What is partition purning .

 How can we optimize partition table perfomance  when performing DML operation .
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Database Engineer
Top Expert 2016
Prune ( meaning ) :

Tu reduce or trim by removing unwanted parts.

To explain at a very basic level,
Consider, there is a table with a 1 year data partitioned on "some date column for example created_date"  on monthly basis

select * from table where created_date=to_date('20160510','yyyymmdd');  -- 10th of May

In given scenario, optimizer will prune the table and search only in "May" partition.
Had the table been not partitioned, entire data would have been scanned thus 12 times the scanning.

To read how partitioning works, please refer metanote :

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