… query is still much faster second time I run it, why is that ? The answer to this question is simple – because SQL_NO_CACHE only bypasses query cache but it has no change on other caches, which are MySQL Caches – Innodb Buffer Pool and …
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…query log output. The stock MySQL server’s limitation of one-second granularity makes it hide problem queries that are faster than one second…time. We also frequently bring the discussion to topics such as monitoring, alerting, backups, caching…
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 27 Comments
…no cost of the join in this case because there is really no join: mysql> EXPLAIN select SQL_NO_CACHE…query times longer. 1) Results for ENUM: select SQL_NO_CACHE city, state from cities_enum limit 10000, 5; Result time…
Post: Is your server's performance about to degrade?
May 18, 2010 By 13 Comments
…running 20k queries per second and higher, lots of memory, lots of CPU cores, and most queries are running faster…query cache) are executing in no more than 12 microseconds, worst-case. So the contention that’s blocking these queries for shockingly long times… improvements to the MySQL source code are…
Post: Cache Performance Comparison
August 9, 2006 By 73 Comments
…MySQL Query Cache – It performs faster than Query Cache if TCP/IP socket is used, but if Unix Socket is used to connect to MySQL MySQL Query Cache will be faster…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…by index pr second. The difference is 10.000 times for our…MySQL single query runs as single thread (with exeption of MySQL Cluster) and MySQL issues IO requests one by one for query… full table scans are often faster than range scans and other…there is no random IO needed to populate the caches. With …
Post: Getting real life query speeds with MySQL
January 10, 2007 By 10 Comments
…second and further runs, especially when it comes to disk IO workloads. The attempt to fix it is often using SELECT SQL_NO_CACHE or disabling QueryCache for the test. This works by blocking query cache but still repeated runs execute much faster…
Post: Thoughts on MySQL Replication
July 7, 2006 By 18 Comments
…time reads when you want to have 100% guaranty you’re reading latest data. Second…cache Memory is much faster than disk and you generally want to have data you’re accessing to be cached in memory by MySQL cache…running queries. That is all for today but far from being all what can be said about MySQL…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 27 Comments
…running silly queries that do nothing but cause buffer hits, skewing the result towards “this ratio looks great!” The second kind of time…cache hit to be faster than a miss. Hard-to-prove assumption #2: A key cache…
Post: To SQL_CALC_FOUND_ROWS or not to SQL_CALC_FOUND_ROWS?
August 28, 2007 By 53 Comments
…runs. And now – we need too check how long our COUNT query would take: mysql> SELECT SQL_NO_CACHE…seconds for SQL_CALC_FOUND_ROWS. 7+7 seconds in case when two queries used. Filesort: 1.8 seconds…
