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Questions about Executing Explain Plan against a query. [message #249144] Tue, 03 July 2007 08:56 Go to next message
Rustican
Messages: 51
Registered: July 2006
Member
I'm using Oracle SQL Developer and running the Executive Explain Plan against my queries. I was wondering if there was some explanation of what the COST, CARDINALITY, and BYTES were in the explanation.

I'm not sure what is meant by the COST of the query.

I thought the CARDINALITY of a query was the number of rows returned, but it doesn't seem to be the case.

And is the BYTES information the amount of temp table space the query uses in the database when the returned rows are generated?



Re: Questions about Executing Explain Plan against a query. [message #249155 is a reply to message #249144] Tue, 03 July 2007 09:22 Go to previous message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
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Database Performance Tuning Guide, Chapter 19 Using EXPLAIN PLAN, section 19.9 PLAN_TABLE Columns

Regards
Michel
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