… join rows with table t2. This step is called the build step. After the hash table has been created, rows from table t2 are… in the build step is such that the hash table fits in memory. You can read more about the hash join algorithm…_buffer_size=4M & mrr_buffer_size=4M Created_tmp_disk_tables 0 0 0 0 0 0 Created_tmp_tables 1 1 1 1 1 1 Handler…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… MRR when the workload fits entirely in memory. For the purpose of benchmarking in-memory workload, the InnoDB buffer pool size is… workload fits entirely in memory, because there is no extra cost for memory access at random locations versus memory access at sequential locations… 5.5 w/ mrr_buffer_size=4M Created_tmp_disk_tables 1 1 1 1 1 Created_tmp_tables 1 1 1 1 1 Handler_mrr_init…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
I have been working with Peter in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at and benchmarking optimizer enhancements one by one. So in the same way this blog post is aimed at a new optimizer enhancement Index Condition …
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…Created_tmp_disk_tablesblogpercona.commanual Created_tmp_filesblogpercona.commanual Created_tmp…memory…
Comment: MySQL Server Memory Usage
September 1, 2006 By 18 Comments
…unlock_tables‘, ’102′ ‘Com_update’, ’15146253′ ‘Com_update_multi’, ’0′ ‘Connections’, ’263413′ ‘Created_tmp_disk_tables‘, ’0′ ‘Created_tmp_files’, ’4001′ ‘Created_tmp_tables…streams’, ’0′ ‘Open_tables‘, ’512′ ‘Opened_tables‘, ’183240′ ‘Qcache_free_blocks’, ’136′ ‘Qcache_free_memory‘, ’10272736′ ‘…
Comment: Why MySQL could be slow with large tables ?
November 14, 2008 By 139 Comments
… M Handler_read_rnd_next 4,483 M Created_tmp_disk_tables 5,270 Created_tmp_tables 5,274 Created_tmp_files 37 k Key_reads 4,226 Key…, 3Tb SATA disk space Load avg: 0.81 (1 min) 0.68 (5 mins) 0.73 (15 mins) Real memory 3.86 GB total, 1.38 GB used Virtual memory 4 GB total, 288 kB used…
Comment: How much memory can MySQL use in the worst case?
February 19, 2009 By 17 Comments
…. We are currently using MySQL and MyISAM tables and we keep running out of memory so the server starts to swap and… server runs) Created_tmp_disk_tables 9,208 Select_full_join 1,074(the application is using indexes to join the tables so this puzzles… Opened_tables 1,500 Table_locks_waited 74 hope this is enough information to help you help me. The server has 6GB memory…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…: 68 Tmp_tables: 0 Tmp_disk_tables: 0 Tmp_table_sizes: 0 # InnoDB_trx_id: F00 # QC_Hit: No Full_scan: Yes Full_join: No Tmp_table: No Tmp_table_on_disk… and the average query execution time, the number of tmp tables created in memory vs on-disk, percentage of queries that needed full scan, InnoDB…
Post: TMP_TABLE_SIZE and MAX_HEAP_TABLE_SIZE
January 19, 2007 By 16 Comments
…disk table. The size limit is determined by the value of the tmp_table_size system variable. * MEMORY tables are never converted to disk tables…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
… MySQL needs to create temporary tables, which can be created in memory, using MEMORY storage engine or can be created on disk as MYISAM tables. Which one will be used depends on the allowed tmp_table…
