Re: Deleting partitioned data

Jonathan,

Oracle9i SQL Reference Release 2 (9.2)

SELECT PARTITION | SUBPARTITION For PARTITION or SUBPARTITION, specify the name of the partition or subpartition within table from which you want to retrieve data.

For range- and list-partitioned data, as an alternative to this clause, you can specify a condition in the WHERE clause that restricts the retrieval to one or more partitions of table. Oracle will interpret the condition and fetch data from only those partitions. (It is not possible to formulate such a WHERE condition for hash-partitioned data.)

-- 
Vladimir Begun
The statements and opinions expressed here are my own and
do not necessarily represent those of Oracle Corporation.

Jonathan Gennick wrote:


> I'd like to ask a question. Consider the two statements

> below:

> 

> DELETE

> FROM county PARTITION (michigan)

> WHERE county_name = 'Alger';

> 

> DELETE

> FROM county

> WHERE county_name = 'Alger'

>   AND state = 'MI';

> Is there ever a case where the first option is preferable?

> Is there ever a case where Oracle wouldn't be able to

> isolate the partition of interest simply by evaluating the

> conditions in the WHERE clause? There must be, else why

> would Oracle provide the syntax shown in the first

> statement? However, I'm having difficulty coming up with a

> good example of when that syntax makes sense. Can someone

> help me out here?



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Author: Vladimir Begun
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