![]() Over the next few minutes, you'll discover how this works by exploring the concept of stored procedures. There must be an easier way, right? Well, with MySQL, Lucky Shrub can use the stored procedure's method to save a specific query as a block of code that they can then recall whenever required. Each time they perform these queries, they have to rewrite the same SQL code again. Due to FOR EACH ROW only, don’t have expensive SQL in any trigger.Lucky Shrub often perform the same queries on their database every day.Triggers will have a non-trival overhead for even the simplest trigger.extract if comparisions duplicated to produce nested if’s (within reason).Test the most likely IF/THEN statements first.LEAVE or CONTINUE when possible in loops.Only perform necessary code within iterations.Where SQL is tuned, goto tried and proven traditional optimisation techniques. ![]() Performance of SQL in a SP will dominate overall performance. Comparatively the same between Java and SP locally, but much better in a remote host mode. access a million rows, perform some statisical aggretation). On the other hand, if the program is network dependent (e.g. This showed an example that was excessively inefficient. Computionally not a fast language.Ī written routine to calculate prime numbers provided the following performance (from most expensive to least) MySQL SP, Oracle SP,PHP,Perl,Java ,VB.NET ,C (gcc). SP is not optimized for number crunching.SQL is highly optimized for SET operations.Breaking up complex queries may provide benefits.Can improved perfomrance when high network overhead.Stored Procedures provided a mixed blessing for performance. Derived tables – SELECT table in a from clause, creates a temporary table and will never get an index.Ī comment from the audience was that derived tables can be of a benefit to a correlated sub-query in specific examples.covering index (including required columns, customer+product+qty)Įxamples of SQL that can’t benefit from Indexes.concatenated indexes (customer + product).In the following examples, each advancement improved performance. Overloading indexes with additional columns when key queries only use a few columns can enable improved performance.Subqueries need to be satisified by an index or performance will be quite inefficent.Indexes generally effective when between 5% and 20% of rows are accessed.In MySQL Index is the best tool to improve performance, however sometimes it’s better to access the entire table.In addition to the Show Query Log, there are Innodb specific commands, two in particular. There were 4 ways to provide optimizer hints. In this example, An IN was converted to EXISTS Explain Command – reveals what the optimizer intends to do.His talk were on tools and techniques for tuning MySQL. I managed to get for free at the conference from the MySQL Quiz night, in addition to a shirt and cap for stumping a Guru. Guy is author of O’Reilly “MySQL Stored Procedure Programming” Book. ![]() He did make quite a funny comment, “He is now seeking refugee status in the MySQL Community”. In this presentation he stated, nothing he was talking about specifically was relatively new. There are Freeware MySQL product downloads. For these products, MySQL 5 and InnoDB only is necessary, simply due to accessing the right internal information for presentation. His work now is on the “Spotlight” product family – Database diagnositic tools converting data to graphical representations. Guy has written a number of Oracle Performance Books in the past. Another one of the sessions at the MySQL Users Conference I attended was Tuning MySQL5 SQL and Stored Procedures by Guy Harrison from Quest Software. ![]()
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