June 19, 2013

Post: MySQL and the SSB - Part 2 - MyISAM vs InnoDB low concurrency

May 22, 2013 By Leave a Comment

…post I compared MySQL 5.5.30 to MySQL 5.6.10,…caches are dropped at this time as well. These set of queries…joined together (Q4.1, Q4.2) but…, but there are limitations which MyISAM imposes that…mysql socket=/var/lib/mysql/mysql.sock user=justin innodb_buffer_pool_size=64G innodb_log_file_size…

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Post: More on MySQL transaction descriptors optimization

April 26, 2013 By Leave a Comment

…MySQL 5.6 virtually eliminates contention on the mutex protecting the list of transactions, its applicability is quite limited…open_cache=5000 query_cache_…size=1000000 –rand-init=on –report-interval=1 –rand-type=uniform –forced-shutdown=1 –max-time=120 –max-requests=0 –percentile=99 –mysql…

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Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5

April 4, 2012 By 4 Comments

…size ~5G). Note that query cache is disabled during these benchmark runs and that the disks are 4 5…o_orderdate LIMIT 10…MySQL 5.5. MariaDB 5.5 is quite slow as compared to both MySQL 5.5 and MySQL 5.6. For MariaDB 5.5 the query time decreases when the join_buffer_size…1 1 1 1 1 1 Sort_scan 1 1 1 1 1 1…

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Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

March 21, 2012 By 10 Comments

…MySQL 5.5 and ~5 hours in case of MySQL 5.6 and MariaDB 5.5. Note that query cache…_comment order by revenue desc LIMIT 20; In-memory …MySQL 5.5 MySQL 5.6 MySQL 5.6 w/ read_rnd_bufer_size=4M MariaDB 5.5 MariaDB 5.5 w/ mrr_buffer_size=4M Created_tmp_disk_tables 1 1 1 1 1 Created_tmp_tables 1 1 1 1 1…

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Post: How much overhead is caused by on disk temporary tables

August 16, 2007 By 26 Comments

… | 1…5.51 sec) VMSTAT: procs ———–memory———- —swap– —–io—- –system– —–cpu—— r b swpd free buff cache…size=1000000000; Query OK, 0 rows affected (0.00 sec) mysql> select count(*) cnt,c from gt group by c order by null limit…

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Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact

March 12, 2012 By 12 Comments

…for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at … Condition Pushdown Traditional B-Tree index lookups have some limitations in cases such as range scans, where index … defined as: l_partkey = x and l_quantity >= 1 and l_quantity = 1 and l_…

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Post: Review of MySQL 5.6 Defaults Changes

October 8, 2012 By 10 Comments

…of defaults changes in MySQL 5.6 compared to MySQL 5.5 In general …_cache_size = 128 + 1 for each of the first 500 max_connections + 1 …MySQL is typically protected by Firewall to begin with. open_files_limit …default. query_cache_size = 1M Query cache remains off by default but default size is raised…

Filed Under: Insight for DBAs, MySQL

Post: Troubleshooting MySQL Memory Usage

March 21, 2012 By 5 Comments

…MySQL 5.5…Cache Related Allocations There are cases when MySQL will allocate a lot of memory for table cache…query execution, which size can be controlled by tmp_table_size and which also only exist for duration of query…size variable which allows you to limit size of MEMORY tables (the limit… 1…

Filed Under: Insight for DBAs, MySQL

Post: A case for MariaDB's Hash Joins

May 31, 2012 By Leave a Comment

…=O_DIRECT query_cache_size=0 query_cache_type=0 MySQL 5.6.5 Configuration innodb_file_per_table=1 innodb_file_format=barracuda innodb_log_file_size=512M innodb…_switch=’join_cache_hashed=on’ optimizer_switch=’join_cache_bka=on’ join_cache_level=4 join_buffer_size=32M join_buffer_space_limit=32M Note…

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Post: InnoDB Full-text Search in MySQL 5.6 (part 1)

February 26, 2013 By 1 Comment

…1 | | table_state | 0 | +—————————+———+ 10 rows in set (0.00 sec) mysql> delete from dir_test_innodb LIMIT 200000; Query…MySQL 5.6, and that was to change innodb_ft_min_token_size…

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