… MySQL‘s key cache hit ratio is wrong, even when you hear it from experts. There are two major problems with the key buffer hit ratio… they cancel out. The key cache hit ratio is simply one minus the miss ratio. The key_buffer hit ratio The metrics we’re interested in… scientific and authoritative — the “key cache hit ratio.” This is a shame. When you are new to MySQL, trying to configure my.cnf, and…
Post: What MySQL buffer cache hit rate should you target
June 29, 2006 By 5 Comments
… to be understand is – cache hit ratio can be computed differently for different engines. For example for Innodb page hits are counted for all… good was OS or SAN cache hit rate – something you would not see otherwise. The bad luck is – MySQL currently does not provide… other IO – no matter what your hit ratio is it is unlikely the problem for MySQL Performance. If it is however 120 per…
Post: Beyond great cache hit ratio
May 19, 2010 By 2 Comments
…. The great memcached hit ratio is great however even more than that you should target eliminating requests all together. Hit rate is very… gets (hits) to retrieve some data plus there are 10 more requests which resulted in misses and caused MySQL queries. The hit ratio is… multiple pages and multiple users this will maximize cache efficiency while reduce amount of cache space required. The importance of this advice…
Post: Why don't our new Nagios plugins use caching?
February 19, 2012 By 1 Comment
… went further than that; I didn’t cache the data retrieved from MySQL, I cached the resulting metrics. This avoids having to do… there might have been a misunderstanding — perhaps caching was understood to reduce load on MySQL, rather than reducing load on the Cacti… inside of MySQL. If you take the typical mass-market monitoring program’s silly “alert on 99 different kinds of cache hit ratio thresholds…
Post: Cache Performance Comparison
August 9, 2006 By 73 Comments
… queries to MySQL parsing may be performance bottleneck, assuming PHP opcode cache is not used. Also different applications may have different cache hit ratios which… file cache to work you need file named “test” containing “MyTestString” 2) You need to create table test.test for MySQL Cache to…
Post: What to tune in MySQL Server after installation
September 29, 2006 By 116 Comments
… question during Interview for people to work as MySQL DBAs or be involved with MySQL Performance in some way is to ask… transactions even in case MySQL Server crashes. Value 2 only cause data loss with full OS crash. table_cache – Opening tables can… and see if it is well used. For certain workloads cache hit ratio is lower than would justify having it enabled. Note: as…
Post: MySQL Query Cache
July 27, 2006 By 69 Comments
…, thinking MySQL Query Cache is the same as Oracle Query Cache – meaning cache where execution plans are cached. MySQL Query Cache is not. It does not cache the… invalidation which can offer much better hit ratio for certain application. It is not that fast Query Cache is fast compared to running…
Post: KISS KISS KISS
March 1, 2009 By 7 Comments
… using memcache or other caching option. Successful memcache implementations often report 90% cache hit ratio meaning 10 to 1 read ratio drop backs to one… the availability of the application is only related to the MySQL redundancy for very high quality/high scale applications. I’ve seen applications having no downtime running for years on single MySQL server (which just does not crash) as well as complex…
Comment: MySQL Query Cache
January 23, 2011 By 69 Comments
… best to cache (or not cache things). If you have queries which you know cannot be cached then tell mysql not to cache them. It might save some reusable query from being evicted from the cache, and will keep your cache hit ratio up (which is a good thing). Also for tables which are frequently updated, it might be worth not caching some…
Post: Predicting Performance improvements from memory increase
August 7, 2008 By 6 Comments
… way too much IO bound anyway. Interesting enough because of MySQL scaling issues it is also possible to see performance to…% of CPU usage ? This is the true challenge becomes because MySQL has no tools to analyze working set (we have per… estimations and take IO subsystem into account – even with same cache hit ratio more data and more load means there are higher demands…
