One of the very frequent cases with performance problems with MySQL is what they happen every so often or certain times… need to know it is not MySQL problem, might be even not problem with your MySQL configuration, queries and hardware, even though fixing… too much in this case throttling by having relatively short queries and introducing “sleeps” between them can be a good idea…
Post: Joining many tables in MySQL - optimizer_search_depth
April 20, 2012 By 6 Comments
… automatically. Making this change I could bring optimization, and full query execution time to less than 50ms. Low values, such as… further I found the following explanation from Timour Katchaounov in MySQL mailing list archives I have some recollection that there were… than 7 at which complexity is reasonable. This makes Timour explanation somewhat conflicting though as if we assume MySQL users do not…
Comment: Joining many tables in MySQL - optimizer_search_depth
April 23, 2012 By 6 Comments
… fast – 7! = 5040, while 8! = 40320. The worst-case complexity of MySQL‘s join optimizer is N!. The goal of this choice was to provide a conservative limit that guarantees that any query… the change to plan pruning in MySQL 5.6. Ideally, the server should analyze the query and should determine the search depth…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 22 Comments
… Shard-Query over Hive is that it works with existing MySQL data sets and queries. Another advantage is that it works with all MySQL…). In order to demonstrate the power of Shard-Query it is important to test complex queries involving joins and aggregation. A star schema… splitting/loading process will be described in another post. Complex queries Shard-Query was tested with the simple single table version of this…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… of MySQL Performance by complex queries on large data sets(ie some large aggregate queries) and batch jobs. It is not rare to see queries… – query which crunches large amount of data set wipes data from your normal working set from OS cache. Operation Systems and MySQL… it. Make sure the load is low enough so your complex query or batch job do not slow things to bad. In…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
… MySQL Query Cache is most useful for complex expensive queries, for which tracking exact rows used from query syntax may be hard. Query Cache Storage Engines MySQL Query Cache now stores queries in…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
… half the size. You have to write a little more complex queries, but that’s often justified by a large reduction in… in a complex query with many joins. I have never seen this approach scale well. Use The Best Technologies You Can MySQL is… workloads out-of-the-box than MySQL is, especially for more complex queries. Percona is not tied to MySQL, although we’re most famous…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
… up. Running small queries might only barely increase memory consumption for given thread, however if table will perform complex operations such as… not need to increase per thread buffers unless you have complex queries. Sorting 10 rows will be as fast with 1MB sort… to be impractical. Here is why: List of rarely considered MySQL Server Memory Requirements Thread buffers can be allocated more than…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…are used to compose the complex object which was previously normalized to several tables or perform complex queries finding relationships between objects. … In MySQL single query runs as single thread (with exeption of MySQL Cluster) and MySQL issues IO requests one by one for query execution, …
Post: MySQL Query Cache
July 27, 2006 By 69 Comments
…query cache offering about double performance for simple queries with select done by primary key, obviously there is no upper boundary – Very complex queries…
