… the importance of the size of the buffer used for sorting the secondary key tuples. If the buffer size is large enough only…=’mrr_sort_keys=on’ (only on MariaDB 5.5) optimizer_switch=’mrr_cost_based=off’ read_rnd_buffer_size=4M (only on MySQL… MySQL 5.6 w/ read_rnd_bufer_size=4M MariaDB 5.5 MariaDB 5.5 w/ mrr_buffer_size=4M Created_tmp_disk_tables…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
… optimizer_switch=’mrr=on’ optimizer_switch=’mrr_sort_keys=on’ optimizer_switch=’mrr_cost_based… MySQL 5.5 MySQL 5.6 MySQL 5.6 w/ join_buffer_size=6M & read_rnd_buffer_size=…size=6M & mrr_buffer_size=6M MariaDB 5.5 Hash Join Disabled w/ join_buffer_size=4M & mrr_buffer_size=4M Created_tmp_disk_tables…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
… to the amazing MySQL manual, especially the option and variable reference table. But just as …socketblogpercona.commanual sort_buffer_sizeblogpercona.commanual Sort_merge_passesblogpercona.commanual Sort_rangeblogpercona.commanual Sort_rowsblogpercona.commanual Sort_scanblogpercona.commanual…
Post: Can we improve MySQL variable handling ?
February 18, 2012 By 8 Comments
…table-size 16777216 tmpdir /tmp transaction-alloc-block-size 8192 transaction-isolation REPEATABLE-READ transaction-prealloc-size…
Post: How fast can you sort data with MySQL ?
August 18, 2007 By 26 Comments
…table scan of the query and considering table size was about 60MB we have 120MB/sec sort…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
… such as full table scans, sorts, or need temporary tables as much as read_buffer_size, sort_buffer_size, read_rnd_buffer_size, tmp_table_size of memory might… chunk at once others, for example tmp_table_size is rather maximum amount of memory MySQL will allocate for this operation. Note it…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…tables in MyISAM format in “mysql” database. Plus HEAP/MEMORY tables are used for temporary tables…table_size This variable specifies maximum size implicit temporary table (created during query execution automatically) will grow as MEMORY table…
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
…=100 table_cache = 6000 read_rnd_buffer_size = 2M sort_buffer_size = 32k thread_cache = 16 query_cache_size = 0M thread_concurrency = 8 max_heap_table_size=200M log-output = FILE log-slow-queries=/tmp/mysql…
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
…could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections”. This was never …about the query cache and the table cache and the size needed for each thread (thread …); Query OK, 0 rows affected (2.34 sec) mysql> select get_lock(@a, 1); +—————–+ | get_lock(@a, 1) …
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
… allowed connections to ALTER 100 different tables ? This can be offset by keeping myisam_sort_buffer_size low, but then performance would suffer…_table_size or max_prepared_stmt_count are designed to protect from typical application mistakes not from someone intentionally trying to bring MySQL…
