… size of the sort_buffer. It is my understanding that the sort_buffer is used when no index are available to help the sorting so I created a MyISAM… time for the queries loses all dependency over the sort buffer size. I am still trying to figure out why the number of sort merge passes felt to…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…for Full Table Scan (read_buffer) and for reading rows in sorted order (read_rnd_buffer_size). Other storage engines such as Innodb to not use this variable. sort_buffer_size Buffer used to sort…
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
…sort performance and today I’ve discovered even read_buffer_size…MyISAM DEFAULT CHARSET=latin1 1 row in set (0.00 sec) Populated it with 75M of rows to reach 4G in size…size for read_buffer_size, this is why…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…Buffers, Indexes and Joins. Buffers First thing you need to…), multi-server partitioning to use combined memory and…for MyISAM tables. Now if we take the same hard drive for fully IO bound workload it will be able to… be placed in sorted way or pages placed…to disaster. The problem is not the data size …
Post: table_cache negative scalability
November 16, 2009 By 23 Comments
…size also sort_buffer_size and read_buffer_size may not give you better performance if you increase them. I found this also applies to some other buffers… sync_frm option is used. With default table_cache=…to the disk during this read-only benchmark. Why ? Because for MyISAM tables table header has to…
Post: Are larger buffers always better ?
June 6, 2006 By 9 Comments
…sort_buffer_size – recently I worked with case which was running much faster with 32K sort_buffer_size, compared to 32M. The problem was memory allocation – sorting was used…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…to read. If the InnoDB buffer pool is set to 22GB, it’s much easier to…to convert MyISAM tables to…for serious analysis it’s basically mandatory to use a server that has the Percona patches for…
Post: To UUID or not to UUID ?
March 13, 2007 By 28 Comments
…size it is way overturned by BTREE buffer. The most efficient approach here is not to use auto_increment but use certain partitioned sequences, for…to publish some insert benchmark for this case with larger data size so here they are: I’ve created MyISAM…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
…allocate bulk_insert_buffer_size bytes of memory if done to MyISAM tables. myisam_sort_buffer_size used for ALTER TABLE, OPTIMIZE TABLE, REPAIR TABLE commands. For OLTP applications…users will decide to run. Unfortunately this is as much close to impossible to be impractical. Here is why: List of …
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
…buffer pool in many cases). I also should mention this feature is not that easy to use…for MyISAM tables). Are there any plans to be able to build indexes in parallel by running sorts in different threads – using…
