…MySQL 3.23 when there would only handful of places where memory could be allocated but it is a lot larger problems with MySQL…Table Cache Related Allocations There are cases when MySQL will allocate a lot of memory for table cache…
Post: Finding out largest tables on MySQL Server
February 4, 2008 By 24 Comments
…tables on MySQL instance is no brainier in MySQL 5…10M | 10.11G | 3.59G | 13.70G | 0.35 | | art104.link_out104 | 23.66M | 6…79G | 0.17 | +————————————-+——–+——–+——–+————+———+ 10 rows in set (2 min 29.19 …system cache. I also use it to see which tables…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 11 Comments
…MySQL configurations, I didn’t try out different MySQL versions or settings…table_cache = 2048 max_allowed_packet = 16M binlog_cache_size = 16M max_heap_table_size = 64M thread_cache_size = 32 query_cache_size = 0 tmp_table…
Post: Using Multiple Key Caches for MyISAM Scalability
November 26, 2008 By 8 Comments
…tables to the key caches: mysql> select concat(“CACHE INDEX “,table_schema,”.”,table_name,” IN “,table_schema,”_”,table_name,”;”) from information_schema.tables where table_schema=’test’ and table…
Post: Top 5 Wishes for MySQL
June 29, 2007 By 10 Comments
…set to deal with multiple nodes nicely even if you do not have much support from MySQL…tables and other tricks we use when such need arises but we still can’t deny – MySQL… we had successful production on 3.23 alpha). However many of … Statements in MySQL 4.1 which came without query cache support but…
Post: Wanted: Better memory profiling for MySQL
May 18, 2008 By 4 Comments
… other global buffers such as query_cache_size and key_buffer and …it be some buffers associated with opened tables, prepared statements etc ? Could it …on per connection settings ? It also could be memory leak in MySQL or … memory usage have not improved since MySQL version 3.23, in fact were newer …
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 27 Comments
… of advice about tuning MySQL‘s key cache hit ratio is wrong,…a key cache miss ratio of 23% Server #2 has a key cache miss… anyway: Hard-to-prove assumption #3: A Key_read might …that’s dedicated to MyISAM tables. Consider your mixture of storage …for how big your working set is. Set the key_buffer_size…
Comment: COUNT(*) vs COUNT(col)
April 25, 2007 By 41 Comments
…cache, and using O_DIRECT to bypass OS caching) mysql> explain select count(*) from wp_comments; +—-+————-+————-+——-+—————+———+———+——+——–+————-+ | id | select_type | table…
Post: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
…cache and uncached IO performance. We’re interested in cached reads because they may show latency to the RAID cache if RAID read cache…MySQL. To prepare small 128MB single file working set… look at another table SysBench displays: per-request … 0 0 37760 23 3402 6932 0…73 27 1 3 90560 5305556 86932…
Post: A micro-benchmark of stored routines in MySQL
August 16, 2009 By 7 Comments
… | 237134840 | +——————–+ 1 row in set (0.23…mysql> delimiter // mysql> create function speaks_english(c char(3…mysql> delimiter ; Now the query can be rewritten as this: mysql> select sql_no_cache…set (1.00 sec) If we explain it, we get output similar to the first table…
