…. A second confirmation that key_cache is a problem is benchmark run with disabled key_cache (=0). Results for MyISAM with key_buffer_size=0 Threads queries… is comparison of MyISAM Innodb and Falcon results in the graphical form: I’ve created bug, for MyISAM key cache contention issue and lets…
Post: Crashes while using MyISAM with multiple key caches
July 18, 2009 By Leave a Comment
… multiple key caches but to online key cache resize. It is just this code most actively used in case you’re using multiple key caches. It is very rare one would resize single key cache in production and it only triggers… be buggy and crashing I’d like to see them disabled as run time and enabled with –enable-buggy-features switch…
Post: To pack or not to pack - MyISAM Key compression
May 13, 2006 By 3 Comments
MyISAM storage engine has key compression which makes its indexes much smaller, allowing better fit in caches and so improving performance dramatically. Actually… PACK_KEYS=0|1|DEFAULT. Value 0 disables compression for all keys. Value 1 forces it for all keys. Value DEFAULT will use key compression…
Post: MySQL MyISAM Active Active Clustering - looking for trouble ?
March 15, 2007 By 4 Comments
… Active Active Clustering and MyISAM tables if you follow certain rules like enabling external locking, disabling query cache and delayed key writes etc. This… locks besides extra overhead you get from external locking. Plus key cache have to be invalidated with remote writes which makes even…
Post: Using CHAR keys for joins, how much is the overhead ?
June 18, 2007 By 18 Comments
… Innodb tables MyISAM Tables may suffer significantly if key compression is not disabled Joining on Shorter CHAR keys is significantly faster than Long keys Latin1… be different as longer indexes expected to have much worse cache fit, especially if you keep them unpacked.
Comment: Why MySQL could be slow with large tables ?
November 29, 2006 By 139 Comments
…due to wrong configuration (ie too small myisam_max_sort_file_size or myisam_max_extra_sort_file_size) or…about 20% done. The problem is – unique keys are always rebuilt using key_cache, which means we’re down to some…. You can’t go away with ALTER TABLE DISABLE KEYS as it does not affect unique keys…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 11 Comments
… thread_cache_size = 32 query_cache_size = 0 tmp_table_size = 64M key_buffer_size = 8M bulk_insert_buffer_size = 8M myisam_sort_buffer_size = 8M myisam_max… WT cache: The second is with WB cache: I couldn’t figure out what exactly happened with setting #3 when WB cache was disabled…
Post: MySQL Performance on Memory Appliance
March 31, 2008 By 23 Comments
…in such condition – normal case is to allocate cache memory to buffer pool so IOs will mostly… it back to the client. I tested MyISAM with myisam_use_mmap option which did not seems to…. I also tried running with key buffer on and off. Interesting enough disabling key buffer actually worked better for…
Post: Choosing innodb_buffer_pool_size
November 3, 2007 By 38 Comments
… needs – these include MySQL buffers – query cache, key_buffer, mysql threads, temporary tables, per …cache. You want to bypass cache for your Innodb tables but there are other things you need OS cache for – MyISAM… all kernels work quite well with swap disabled and there are other reasons against it…
