…, free, fast-paced and very technical MySQL educational event for wide range of people interested in MySQL – Developers, System Administrators, DBAs, etc. It will be held at Portland State University’s Smith Memorial Student Union. We’ll… to the cities showing greatest interest. As usual space is limited, so Register Now!
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
….10 | | BACK_LOG | 50 | 80 | | OPEN_FILES_LIMIT | 1024 | 5000 | | INNODB_AUTOEXTEND_INCREMENT | 8 | 64 | | …of 1MB now allowing MySQL to handle larger queries. Makes sense as amount of memory available is …: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,…
Post: MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
…of indexes. The indexes can’t fit in memory anymore. How does this affect performance? A: …in recent MySQL versions. However it is often too many. Instead of thinking about hard limit of indexes…you will need to use something like Trick “Unionizing Order by” described in presentation. Q: what …
Post: Possible optimization for sort_merge and UNION ORDER BY LIMIT
September 18, 2007 By 10 Comments
… original query (in memory data) takes 1sec. Let’s see how classic pre MySQL 5.0 solution – using UNION instead of single query… ord desc limit 10) union (select * from utest where c2=5 order by ord desc limit 10) order by ord desc limit 10 \G… to do. P.S This post is inspired by Does MySQL Optimize UNION with LIMIT clause topic on our MySQL Forums.
Post: UNION vs UNION ALL Performance
October 5, 2007 By 15 Comments
…UNION vs MySQL 5.0 index merge algorithm Sinisa pointed out I should be using UNION ALL instead of simple UNION…LIMIT inside of union clause being cool thing. But So is UNION ALL indeed faster than UNION DISTINCT (the UNION is shortcut for UNION…) – Hash indexes used by MEMORY table are very efficient…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… right query in the right way. But vanilla MySQL does have its limitations, it reports only a subset of stats, …these pages in memory. What it says though is that, if this query would run on a cold MySQL instance, then ….5% 51 0.0039 1.00 0.00 SELECT UNION wp_pp_daily_summary wp_pp_hourly_summary wp_…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…memory. A SATA 7200rpm RAID10 battery backed RAID array was used as the underlying storage for the virtual machines. Baseline: The MySQL… over six servers). Due to ICE limitations, the data was split before loading….clauses, subqueries in the FROM clause, UNION or UNION ALL clauses. If none of those …
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
…”Query Cache” which is quite helpful for MySQL Performance optimization tasks but there are …for subselects, inline views, parts of the UNION. This is also common missunderstanding. Works on … might be unsuitable for online applications. Limited amount of usable memory – Queries are constantly being …
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…above. If you have any limitation in resources in a cluster (cpu, memory, disk, power,etc) then … BETWEEN, IN, subqueries in the FROM clause, and UNION operations to operate fully in parallel. Distributed …resource which speaks SQL, but right now only MySQL storage nodes are supported. Amdahl’s law …
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
… query. Sorting and grouping and DISTINCT and UNION may/will also create temp tables; the … 100); Query OK, 0 rows affected (2.34 sec) mysql> select get_lock(@a, 1); +—————–+ | get_lock(@a, 1) | … memory usage, and there cannot be because there are some things that have no defined limits. …
