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SQL performance Tuning help [message #384204] Mon, 02 February 2009 14:45 Go to next message
Messages: 7
Registered: February 2009
Junior Member
I am presently working on certain SQL queries for performance factors.
Thing is I have to first find the queries which are bad in performance by testing nd accordingly re-write or design or anything else needed for the SQL queries.

I am using oracle 10g with TOAD 9.1

(1)Could you all please guide me with the exact detailed steps to measure correctly Performance and how do i do them manually

(2)Another thing is,I have a query and its PLAN gives me a full TABLE SCAN on a Particular table A.the EXPLAIN plan is say 2000
To optimize,i used SQL optimizer(in TOAD) and it put a /*HINT*/ in the SELECT for the above table A.This removed the full table scan.the EXPLAIN plan is say 1500

Still,no one supported for the HINT whose plan cost is less.

So,i wanted to know why is it not good generally putting a HINT on a table which does full scan.
The reason i got and which confused me was in FULL TABLE SCANS-oracle nullifies the Rules applied.

Can you all please explain me the best one of these

Re: SQL performance Tuning help [message #384205 is a reply to message #384204] Mon, 02 February 2009 14:48 Go to previous message
Michel Cadot
Messages: 65084
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
You can first read:
- OraFAQ Forum Guide, Performance Tuning section
- Performances Tuning sticky
- OraFAQ Performance Tuning
- Rosco's SQL Tuning Guide

Then provide the requested and usual information.

You can also have a look at Database Performance Tuning Guide.

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