How to find the program performance

Question

Hi SAP Gurus,
I came to know that we can check the object performance with se30 t.code. 
There we can find all the components performance of the system.
My question is !
If the performance is calculate by the request and response time, some times server is in good speed and sometimes in normal speed to execute.  If i execute the same program in both the cases,  Is there any changes in runtime analsys.  If yes how can we find the perfect performance of my object.
Please give me the answer you will be rewarded with points for the best answer. 
thanks
kishore

Answer 1

Hi kishore,
ols available in SAP to pin-point a performance problem
The runtime analysis (SE30)
SQL Trace (ST05)
Tips and Tricks tool
The performance database
Optimizing the load of the database
Using table buffering
Using buffered tables improves the performance considerably. Note that in some cases a stament can not be used with a buffered table, so when using these staments the buffer will be bypassed. These staments are:
Select DISTINCT 
ORDER BY / GROUP BY / HAVING clause 
Any WHERE clasuse that contains a subquery or IS NULL expression 
JOIN s 
A SELECT... FOR UPDATE 
If you wnat to explicitly bypass the bufer, use the BYPASS BUFFER addition to the SELECT clause.
Use the ABAP SORT Clause Instead of ORDER BY
The ORDER BY clause is executed on the database server while the ABAP SORT statement is executed on the application server. The datbase server will usually be the bottleneck, so sometimes it is better to move thje sort from the datsbase server to the application server.
If you are not sorting by the primary key ( E.g. using the ORDER BY PRIMARY key statement) but are sorting by another key, it could be better to use the ABAP SORT stament to sort the data in an internal table. Note however that for very large result sets it might not be a feasible solution and you would want to let the datbase server sort it.
Avoid ther SELECT DISTINCT Statement
As with the ORDER BY clause it could be better to avoid using SELECT DISTINCT, if some of the fields are not part of an index. Instead use ABAP SORT + DELETE ADJACENT DUPLICATES on an internal table, to delete duplciate rows.
Rgds,
P.Nag