…accesses to non-checked tables fail with table does not exist error rather than wait forever. Hidden corruptions. If could…queries failing to run, wrong result sets or crashes. Here is my list what I think MyISAM tables are good to be used for…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
…access type in EXPLAIN makes it very confusing. I also was wrong about bug in key length in 5.0 explain. Actually I used…queries to see what exactly happens during query execution – very helpful for MySQL Performance optimization: mysql> flush status; Query…could…
Post: How number of columns affects performance ?
September 28, 2009 By 12 Comments
…what matters or if number of columns we have to work with also have an important role. I…for first table and 101 byte for second and third. I used simple scan query: select max(t1) from t100; for…for accessing…
Post: Is there room for more MySQL IO Optimization?
January 3, 2013 By 11 Comments
… MySQL uses …I think it is still pretty well representative. I have an… for OS Cache….queries, though this is really not the point. The point is I have discovered with the buffered IO mode the query…be accessed next -…could be very valuable addition. MySQL 5.6 has more changes in IO code including what…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
…not take into account locality of access, as you could be reading the same page …an impact on MRR performance, and BKA uses the MRR interface, so these buffers indirectly impact BKA performance. I…for MariaDB 5.5 for in-memory workload. I intend to run tests to see what specific types of queries…
Post: Living with backups
November 6, 2008 By 28 Comments
…there for a long time. Since memory access is way faster than any disk access…queries quick enough. What can be done about it? Nothing really when you are using …of MySQL. Such danger may for example come from an unexpected spike in load…t do anything about. So what I thought could be done here as the …
Post: Read/Write Splitting with PHP Webinar Questions Followup
January 23, 2013 By 4 Comments
… extensions I‘m experimenting with are meant for environments that use… the query against the master. Q: What are…could have an easier time keeping up with changes written by the master, and each slave would “specialize” by serving read queries for… subsequent queries. This allow you speedy access to…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…query times for MySQL 5.6, when the workload fits entirely in memory, because there is no extra cost for memory access…used by MRR had to be reinitialized, because the buffer was small and not all index tuples could…query execution plan. Let’s take a look at what are the good and bad query…
Post: Using Flexviews - part one, introduction to materialized views
March 23, 2011 By 3 Comments
…query is logically an in-memory table The output of a SQL query, and what… is accessed. If multiple statements access the same… completely recalculated, which could be very expensive …for change-data capture. Some extra storage is used for the changes and deltas. Creating an MV is not as simple as I…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
…of access is so common in files. The wear leveling is used for flash memories. I looked … (concurrent queries, autoincrement, concurrent inserts, instrumentation, etc.). Rather than treat each defect as an … or bug in implementation. I‘ll check with Alexander or check myself to see what it could…
