…key cache hit ratio is wrong, even when you hear it from experts. There are two major problems with the key…key cache hit ratio should be very high, ideally above 99.9%” or “if your key cache hit ratio is low, your key…
Post: Using MyISAM in production
June 17, 2006 By 35 Comments
… of thouse other behaviors … well table locks was the problem at very early stage but it was solved by using this significant… you have decent myisam_sort_buffer_size and large myisam_max_sort_file_size otherwise recovery may be done by key_cache rather than sort which can take even longer. Be careful with myisam_recover. This is great…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…quite possible scenario for MyISAM tables. Now …are also clustered keys in Innodb …large tables, which is completely disk bound can be very slow. One of the reasons elevating this problem…caches. With proper application architecture and table design you can build applications operating with very large…
Post: What MySQL buffer cache hit rate should you target
June 29, 2006 By 5 Comments
…What cache hit rate is good for optimal MySQL Performance” is typical question I’m asked. It could by MyISAM key_buffer or… still have problems with key buffer efficiency. In the real world even single operation may be IO bould while showing very large hit rate… IO requests which are not cached by OS or SAN this is likely to be IO bound problem. Yes this still includes…
Post: Should you move from MyISAM to Innodb ?
January 12, 2009 By 53 Comments
…key, caching data, higher concurrency, background flushes while on the drawbacks side we see significantly large…, slower blob handling, concurrency issues, problems dealing with very large number of tables, slow data…re running MyISAM but instantly break upon upgrading to Innodb. Features The MyISAM …
Post: MySQL Crash Recovery
July 30, 2006 By 26 Comments
…MyISAM Corruption – If you’re writting to MyISAM tables there is very large…MyISAM key_cache this can be done by using LOAD INDEX INTO CACHE statement, for other storage engines it can be done by issuing large…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
…to this problem. The reasons are – this formula is very complex … There can be mutiple key caches. Multiple key caches can be created to …have very large memory consumption Innodb Table Cache. Innodb has its own table cache…of memory MyISAM buffers. MyISAM may allocate buffer which is large enough …
Post: MySQL EXPLAIN limits and errors.
July 24, 2006 By 6 Comments
… of key_cache as it can for MyISAM. EXPLAIN may take long time In MySQL 5.0 with addition of greedy join the problem on looking at too many table join combinations in joins with very large tables is elevated, however… shows it will scan over 1000. This is not the problem if you examine your queries manually but if you have…
Post: What to tune in MySQL Server after installation
September 29, 2006 By 116 Comments
…MyISAM tables exclusively. Right size depends on amount of indexes, data size and workload – remember MyISAM uses OS cache to cache…MyISAM. MyISAM may work kind of OK with default key_buffer_size even with large…problem…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
…large enough to fit all key blocks from temporary table index, so we get a lot of key writes which kill performance. The problem…key_buffer_size is important for MyISAM temporary tables performance to avoid OS writes OS Write cache…
