…using the sorted primary key values. Let me give you a simple example. Suppose you have …in MySQL 5.6 code? As MRR was used in both MySQL 5.6 and MariaDB 5.5. Handler_mrr_rowid_refills counts how…value in the index record to make a lookup in the PK. Both these lookups are performed in a single call to…
Post: Using UNION to implement loose index scan in MySQL
August 10, 2006 By 15 Comments
…MySQL Will not use indexes in all cases when it is technically possible. For multiple key part indexes MySQL will only be able to…MySQL Optimizer would handle this case right it would not be but in this case we only can give a hand to MySQL…
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
…indexes built by sorting in case of ALTER TABLE (the big Gotcha for MyISAM tables). Are there any plans to be able to build indexes in…giving you problems if you have a lot of concurrent inserts happening to…in MySQL 5.2 or even MySQL 5.1. I surely would like to see it sooner at least in…
Post: How to estimate query completion time in MySQL
April 22, 2008 By 14 Comments
… a query in MySQL and wondered how long it’ll take to complete? Many people have had …MySQL to perform the query as a table scan of the fact table, then an index lookup in each dimension table in…more complicated ones to consider, but hopefully this gives you an idea how you can tackle this problem in…
Post: MySQL Consulting - Being on your own
February 20, 2007 By 7 Comments
…in my professional life. In SpyLOG I was second person in the company and completely managed technical department, later in MySQL…how to do the things but also implementing things ourselves, which gives quite a different prospective in…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…how to read these, there’s a full explanation in our book, High Performance MySQL 2nd Edition (it’s not in…consider any one of these factors (schema, queries, indexing) in isolation, because they are tightly bound together, …I find out which are the most likely to give the greatest gains. I use a dual…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
…index as p using(index_id) where t.schema=’test’ group by i.index_id \G INDEX…to non zero value, if not I would strongly suggest changing default from zero in MySQL…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 27 Comments
…know enough about the servers. OK, I’ll give you more information. Both servers are real production…whether index I/O might be causing a performance problem. But I haven’t shown you how to …instrumentation in MySQL to guide your decisions. It is also not the be-all and end-all of MySQL performance…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
…in it was only recently found and fixed: http://bugs.mysql.com/bug.php?id=29560 Concerning a switch to… of RAM, to give INNODB ~70-80% of the total RAM, and leave the rest to the OS…how long will this take? Is there a facility we can run to show any table / index fragmentation, without having to…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…indexes. In fact even MySQL optimizer currently does not take it into account. For In memory workload index…to perform 30 millions of random row reads, which gives…
