… 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…:100″ or “your key cache hit ratio should be very high, ideally above 99.9%” or “if your key cache hit ratio is low, your key… about the key cache hit ratio. Bad advice #2: you should set your key_buffer_size according to this ratio. Tuning by ratio is one…
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… (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: 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… 99 hits, making your hit ratio 99% for what would be 0% in many peoples mind. But what is even more important is hit ratio…) while there is no other IO – no matter what your hit ratio is it is unlikely the problem for MySQL Performance. If…
Post: Cache Performance Comparison
August 9, 2006 By 73 Comments
… performance bottleneck, assuming PHP opcode cache is not used. Also different applications may have different cache hit ratios which also needs to be factored…: Cache Type Cache Gets/sec Array Cache 365000 APC Cache 98000 File Cache 27000 Memcached Cache (TCP/IP) 12200 MySQL Query Cache (TCP/IP) 9900 MySQL Query Cache…
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… shortcoming. I did not like writing my own cache management code. Handling cached data correctly is one of the two hard things… monitoring program’s silly “alert on 99 different kinds of cache hit ratio thresholds” approach, you’ll soon have sysadmins with /dev/null…
Post: MySQL Query Cache
July 27, 2006 By 69 Comments
… queries as if query cache hit happens Com_select is not incremented. But if you have just 20% Cache hit rate does it mean… bad. With other caches you may implement version based or timeout based invalidation which can offer much better hit ratio for certain application. It is not that fast Query Cache is fast compared to running…
Comment: Choosing innodb_buffer_pool_size
January 13, 2009 By 38 Comments
… “Free buffers”) and you still don’t have everything cached (Buffer pool hit rate < 1000), your response time will go 2 or... than the response time you get while building up the cache. Example, say you have 100 processes reading off the database… to 20ms while cache is building up (free buffer decrease, cache hit ratio increase). But now, your cache is full and your cache hit ratio is at 95…
Post: KISS KISS KISS
March 1, 2009 By 7 Comments
… copy of data on the disk, wasting resources but their caches are also highly redundant defeating the fact you may have… 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… lot of slaves if your application allows use of efficient caching. Now lets look at the simplified case – you got pair…
Comment: MySQL Query Cache
January 23, 2011 By 69 Comments
… to gently guide MySQL as to how best to cache (or not cache things). If you have queries which you know cannot… 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: What to tune in MySQL Server after installation
September 29, 2006 By 116 Comments
… indexes, data size and workload – remember MyISAM uses OS cache to cache the data so you need to leave memory for it… expensive, especially if you do not have Battery backed up cache. Many applications, especially those moved from MyISAM tables are OK… and see if it is well used. For certain workloads cache hit ratio is lower than would justify having it enabled. Note: as…
