…join_buffer_size=6M & read_rnd_buffer_size=6M MariaDB 5.5 MariaDB 5.5 w/ join_buffer_size=6M & mrr_buffer_size=6M MariaDB 5.5 Hash Join Disabled w/ join_buffer_size…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… is the importance of the size of the buffer used for sorting the secondary key tuples. If the buffer size is large enough only a single range lookup will be needed, however if the buffer size… lookups as well. But this works only with joins and specifically with Block Access Join Algorithms. So I am not going to…
Comment: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
… + join_buffer_size + sort_buffer_size + binlog_cache_size…) is so much misleading. In particular, the join_buffer_size, sort_buffer_size are interesting to note: sort_buffer_size is only used when sorting without index join_buffer_size is only used when joining without index So…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…insert_idblogpercona.commanual interactive_timeoutblogpercona.commanual join_buffer_sizeblogpercona.commanual keep_files_on_…socketblogpercona.commanual sort_buffer_sizeblogpercona.commanual Sort_merge_passesblogpercona.commanual Sort_rangeblogpercona.commanual Sort_rowsblogpercona.commanual Sort_…
Post: How is join_buffer_size allocated?
July 5, 2010 By 9 Comments
…to know how various buffer sizes are used. This matters because some buffers (sort_buffer_size for example) are allocated to their full size immediately as …needed (key_buffer_size). There are many examples of this. What about join_buffer_size? I saw a my.cnf with a 128M join_buffer_size the other…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…dealing with very large data sets are Buffers, Indexes and Joins. Buffers First thing you need to take …from in-memory data size and expect gradual performance decrease as database size grows you may be …join methods at this point (the work is on a way) – MySQL can’t do hash join or sort merge join…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…currently works with MyISAM tables these are MyISAM related. join_buffer_size Buffer used for joins without indexes and few other cases. It is …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 result set…
Comment: MySQL: what read_buffer_size value is optimal ?
September 21, 2008 By 25 Comments
… buffers to 128 kbyte? I put this in my my.cnf: key_buffer_size = 256M sort_buffer_size = 128K read_buffer_size = 128K read_rnd_buffer_size = 128K join_buffer_size = 128K myisam_sort_buffer_size… to the my.cnf): key_buffer_size 268435456 sort_buffer_size 131064 read_buffer_size 126976 read_rnd_buffer_size 126976 join_buffer_size 126976 myisam_sort_buffer_size 131072 The key_buff shows the…
Post: MySQL Session variables and Hints
December 28, 2006 By 2 Comments
…) JOIN B The other part is session variable. If you know query is going to require large sort you can do SET sort_buffer_size=50000000 before executing query and SET sort_buffer_size=DEFAULT after executing the query…
Comment: FreeBSD tests
August 4, 2006 By 15 Comments
…_cache_size=1M \ –max_heap_table_size=64M \ –sort_buffer_size=64K \ –join_buffer_size=1M \ –thread_cache=16 \ –thread_concurrency=16 \ –thread_stack=196K \ –query_cache_size=0…_buffer_pool_size=256M \ –innodb_additional_mem_pool_size=20M \ –innodb_log_file_size=900M \ –innodb_log_files_in_group=2 \ –innodb_log_buffer_size=8M…
