…some events ? If you can’t get fancy graph quickly you can use… and not): mysql> select * from information_schema.global_temporary_tables \G *************************** 1. row *************************** SESSION_… to global memory allocation and will result in increased memory allocation until server …
Post: InnoDB's gap locks
March 27, 2012 By 14 Comments
… to avoid phantom reads and to get a consistent Statement based replication. To accomplish that, row level locking databases also acquire gap… lock, when you run the same query twice, you get the same result, regardless other session modifications on that table. This makes… lock struct(s), heap size 1248, 3 row lock(s), undo log entries 1 MySQL thread id 3, OS thread handle 0x7f84a78ba700…
Post: Best kept MySQLDump Secret
March 23, 2012 By 11 Comments
…mysql> select count(*) from A; +———-+ | count(*) | +———-+ | 2359296 | +———-+ 1 row in set (1.73 sec) mysql> select * from C; +——+ | t | +——+ | test | +——+ 1 row… SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */; /*!40101 SET … hope if you get some empty tables …
Post: How FLUSH TABLES WITH READ LOCK works with Innodb Tables
March 23, 2012 By 20 Comments
…mysql client, so you might get a feel you can’t connect to the database at all (use mysql…0 | 0 | 1 | +——-+——+———–+———-+————+——+——————————+——————————+———–+—————+———–+ 5 rows in set (0.00 sec) As result …
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a… optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take…
Post: Eventual Consistency in MySQL
November 18, 2011 By 8 Comments
…empty result set, it shows us which rows in Bar are orphans. mysql> INSERT INTO Foo (A,B) VALUES (111,2222), (333,444); mysql…foreign_key_checks.sql | mysql -N | mysql -E *************************** 1. row *************************** test.Bar.ID: 42 DIY RI We can get information about foreign key …
Post: Can we get faster expression handling in MySQL
March 30, 2010 By 7 Comments
… in Sphinx to one in MySQL. The result ? Sphinx scored 3x to 20x faster. Andrew goes to explain results are not 100% comparable… results though this is far from the first notion of this problem I hear about. Many other companies looking to optimize MySQL… computed over hundreds of millions of rows have expressed their concerns with this part of MySQL execution. I’m wondering if we…
Post: Handling big result sets
June 26, 2006 By 13 Comments
…SQL query query to MySQL, without fetching and buffering the result rows automatically, as mysql_query() does. So mysql_query buffers all rows on client …gets two parameters and second one is result mode : MYSQLI_USE_RESULT or MYSQLI_STORE_RESULT. (Also there can be used pair mysql_real_query / mysql…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
… system. For comparison you can checkSysbench Results which Vadim published. For read only workload we get 17x gain from 1 thread to…_p cur_open_with_no_init_func,row_sel_get_clust_rec_for_mysql,row_search_for_mysql,ha_innobase::index_read,handler::read_ra…_func,row_sel_get_clust_rec_for_mysql,row_search_for_mysql,ha_innobase::general_fetch,handler::read _multi_range_next,QUICK_RANGE_SELECT::get_next…
Post: PHP Large result sets and summary tables.
July 6, 2007 By 8 Comments
… crazy. Why ? Because by default mysql_query uses mysql_store_result C library call and buffers all result set in the process memory. Not… query the only real call you can get errors is when you run mysql_query , mysql_fetch_row simply reads data from memory and… well get an error while fetching rows. If you do not check for error it can look as you’ve done with result…
