… the new partition starts getting too big, so Inno starts slowing down again. The factor of 4 speedup that occurs when… because the entire table fits in main memory. Each row is on the order of 30 bytes in the primary table, and so… rows and 55GB RAM, Inno would hit a memory wall. Given that Memory sizes are perhaps 10 times bigger than they were…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
…memory they use). Memory Tables MEMORY tables can take memory. There are implicit MEMORY tables which are allocated for query execution, which size can be controlled by tmp_table…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
… in the build step is such that the hash table fits in memory. You can read more about the hash join algorithm… that of MySQL 5.5. MariaDB 5.5 is quite slow as compared to both MySQL 5.5 and MySQL 5….5 is slow as compared to MySQL 5.6. Next interesting thing are the last two columns of the table above and…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
… slows down a lot once it does not fit in memory the good solution is to make sure your data fits in memory… data you’re going to work with in temporary table etc. Prefer full table scans to index accesses – For large data sets… avoid it. Joins to smaller tables is OK but you might want to preload them to memory before join so there is…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
… consumes too much memory it may be crashing , failing to execute queries or make operation to swap seriously slowing down. On now… memory if done to MyISAM tables. myisam_sort_buffer_size used for ALTER TABLE, OPTIMIZE TABLE, REPAIR TABLE commands. For OLTP applications with simple queries memory…
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
… thread_concurrency = 8 max_heap_table_size=200M log-output = FILE log-slow-queries=/tmp/mysql-slow.log long_query_time = 1 innodb… MEMORY tables use in the benchmarks ? As otherwise you also need to boost tmp_table_size to deal with implicit memory tables. innodb_file_per_table – so I assume storing each table in its own…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
… storage engines transaction logs, slow query log or general log. flush, flush_time Flushing (closing) of tables after query is complete or… to on disk MyISAM table. It does not limit size of temporary table, neither it applies to tables created as TEMPORARY TABLE, even in memory tables.
Post: Predicting Performance improvements from memory increase
August 7, 2008 By 6 Comments
… memory to 32GB. Interesting enough similar can happen for very large working set – for example if your main queries do full table scan of 100GB table it does not matter if you have 16GB or… IO bound and which runs too slow (and affects other transaction) and may be increasing memory is helpful to solve this problem…
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
… full table scans for large table you should set this variable to some high value. Sample my.cnf values on large memory sizes… large requests into multiple ones submitting them to device which slows things down or it could be something else. But the… if we test out smaller table (which fits in OS cache): read_buffer_size impace on in memory tableread_buffer_sizeTime (sec…
Post: table_cache negative scalability
November 16, 2009 By 23 Comments
… as you can if you have enough resources (such as memory). With MySQL common sense however does not always works – we… fully cached which made updates to headers very slow. In the production systems with table headers not in OS cache you often… 660 seconds which is 151 tables/sec which is around 50 times slower. Wow. This is the slow down. We can see…
