… will stop using this optimization method if there are too many combinations to check). Instead you could use JOIN to get list… optimize some nasty queries. It looks like equality propagation is working here (note the number of rows for second table in join… to make MySQL Optimizer to do what we want to do – Just add yet another table to the join so the info…
Post: Using delayed JOIN to optimize count(*) and LIMIT queries
April 6, 2007 By 22 Comments
… contain more information about facts and which need to be joined to get query result. If you’re executing count(*) queries for such result sets MySQL will perform the join even if you use LEFT JOIN so it is not needed which slows… better performance you can “Help” MySQL and remove JOIN for count(*) and do JOIN after limiting result set for retrieval queries. Lets…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 100 Comments
… it is effectively removed from join execution (replaced with constants) and so ORDER BY can be optimized even if it is done… to do ORDER BY with JOIN MySQL still will not be able to use it as Optimizer is not smart enough yet… is indexed) Force index if needed In some cases MySQL Optimizer may prefer to use different index, which has better selectivity…
Post: Database access Optimization in Web Applications.
September 12, 2006 By 10 Comments
This is pretty simple approach I often use called to optimize web application performance if problem happens with few pages. If… remember avoiding accessing database is the best way you can optimize database access. This applies to anything else – if you can… may become a bit problem. Other thing to mention is JOINs – Joins are expensive (relatively of course) and for sure increase amount…
Post: Guidance for MySQL Optimizer Developers
September 20, 2009 By 4 Comments
… large portion of my life working on MySQL Performance Optimization and so MySQL Optimizer is quite important to me. For probably last…. The solution is simple – make optimizer pluggable and make it possible to stick to old optimizer behavior with new MySQL Version. Make… have execution method to resolve query in optimal way – loose index scan, hash join, sort merge join are all the examples of such…
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
… analyses as there are many possible ways query can be optimized. There is however one extremely helpful metric which you can… in set (0.00 sec) In this case we actually join 2 tables but because the access type to the tables… or no” answer but rather helps to understand how much optimization is possible. For example I might have query which uses…
Post: Where does HandlerSocket really save you time?
March 16, 2011 By Leave a Comment
…_pthread_fastmutex_lock 2056062.1262make_join_statistics(…) 1982342.0500btr_search_guess_on_hash 1807311.8690JOIN::optimize() 1771201.8317row_search_for_mysql…) samples%symbol name 180544.1415String::copy(…) 142233.2627make_join_statistics(…) 119342.7376JOIN::optimize() 101402.3261my_wc_mb_latin1 71521.6407my_utf8_uni…
Post: Joining on range? Wrong!
May 17, 2010 By 10 Comments
…range. A very inefficient approach! MySQL was unable to optimize those simple conditions to match both product id and…3 bytes). Also ref shows two columns used in join. SHOW STATUS LIKE ‘Handler_read%’; +———————–+——-+ | Variable_name | Value | +———————–+——-+ | …
Post: Percona MySQL Webinar: Really Large Queries: Advanced Optimization Techniques, Feb. 27
February 18, 2013 By 2 Comments
…=”attachment_12964″ align=”alignright” width=”285″] Really Large Queries: Advanced Optimization Techniques: Wednesday, February 27, 2013 10 a.m. PST[/caption… a 7 table join. In this webinar, we will discuss filling the gap between reading explain output and optimizing really large queries… will cover topics including: • How to start optimizing large queries • The use of denormalization • The effect of join order Interested? Register here.
Post: Is it query which needs to be optimized ?
March 6, 2007 By 9 Comments
… Performance Forum as well as from our customers regarding query optimization… which had one thing in common – It is not query which needed to be optimized. Way too frequently people design schema first and then think… index covered and avoid joins as much as possible. ORDER BY I already wrote about ORDER BY LIMIT Optimization so I will…
