…in only SELECT queries. What this practically means it that you can’t get benefit of…is mysqldump/mysqlhotcopy. It is not fully transparent backup, as it applied TABLE LOCK on copying table…of total database size. Also there is the problem of being able to run custom reporting queries…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
…of Query Cache: Transparent Caching – Caching is fully transparent to the application, and what is very important it does not change semantics of the queries…in chunks so it is even harder to implement. Might not work with transactions – Different transactions may see different states of the database…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
…of the queries in the benchmark. I got some strange results, however, which showed…of the hot portion. This sounds good in theory, but in practice it is problematic. What usually happens is that the full table scans access the table…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…to see what‘s up with the database. The first step is to find out what MySQL …show me things like huge tables that should be archived, tables that I should be aware of if I see them in queries, or what…10 most expensive queries, in total execution time. By the way, the slow query logs in the stock …
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
…is what I found: The fragmentation we speak in this article is filesystem fragmentation or internal table fragmentation which affects performance of full table scan. Not all queries…
Post: How to convert MySQL's SHOW PROFILES into a real profile
February 20, 2012 By 12 Comments
…show the relative amount of time consumed. I’ll profile the “nicer_but_slower_film_list” included with the Sakila sample database…show lost time (the amount of time not accounted by the profiling). That is, the SUM(DURATION) isn’t the same as the total query…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
…of table online. Q38: Seems that adaptive hash indexes are not used for primary key lookups or not showed up in…What is your database like? Do you have a big enough buffer pool? PZ: I guess it may be bug in…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 5 Comments
…query execution, which size can be controlled by tmp_table_size and which also only exist for duration of query execution so it is…SHOW ENGINE INNODB STATUS and look for memory information block, which can use like this: ———————- BUFFER POOL AND MEMORY ———————- Total…
Post: Joining on range? Wrong!
May 17, 2010 By 10 Comments
…query. Our data is a tiny store directory consisting of three very simple tables: CREATE TABLE…Database reads all ordered items where tag is ‘lcd’, which totals to about 120000 rows as shown by the counters in SHOW…
Post: Living with backups
November 6, 2008 By 28 Comments
…queries against each table in the database when mysqldump is used or reading a lot of…in a total disaster after MySQL stops responding to the incoming queries quick enough. What…in at runtime anyway. To check what is the current setting you need to query your block devices. In case of…
