DATABASE PERFORMANCE COOKBOOK

 You’ve completed CSCI 6442 (congratulations!)  You have an MS from GWU (congratulations again!)  You’re working on a project using a DBMS (congrats)  And they think of you as a database guru (congrats?)  And now—a programmer says “I’m having performance problems.”  The boss, of course, tells her to come see you!  How to proceed? SCENARIO

 How loaded is the server?  Which DBMS is being used?  How does the application use SQL?  Identify the queries that are slow  Review the use of SQL—can SQL do more?  Look at the plan for each one  First—check for existence of indexes and their use in the plan  Then—general review of the query and the plan  Recommend changes to indexes and query as appropriate  Get performance test results right away WHERE TO LOOK

 The problem may be at the server  Find that out first  Server may be overloaded  Server may not be administered effectively  Server may not have enough capacity  Sometimes test server does not have production capacity SERVER LOAD

 If either the IBM, Sybase or Oracle family is being used, you can work with it  If MySQL is used, check that NODB is being used. Even then, you have limited options for optimization DBMS CHOICE

 Applications may use SQL for put and get, do all data manipulation in the application  They may issue many SQL statements to get a result that you can obtain with a single statement  Often programmers will just copy another programmer’s SQL to get access to the database, won’t understand a thing  Huge performance gains are available from fixing these problems APPLICATION USE OF SQL

 Usually some SQL statements stand out as performance problems  If they’re all slow, the problem may be in the database server or the application server IDENTIFY PROBLEM QUERIES

 Study the use of SQL in each problem query  Can more function be added to the database and removed from the application? This can improve performance  Look at indexes and their use in the plan  Test alternative formulations of the statement for performance  Recommend changes in SQL statement, indexes WHERE TO LOOK

 Carry out and document results of performance tests on your improvements right away  You want a quantitative record of what you accomplished WHERE TO LOOK

 Share the results of the performance improvement, with due modesty  You are a hero, take the credit TAKE THE CREDIT