… parallel processes heavily writing to database. Introduce Throttling Sometimes even single process overloads system too much in this case throttling by…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… tuples. If the buffer size is large enough only a single range lookup will be needed, however if the buffer size… MRR can be controlled by the variable read_rnd_buffer_size, while MariaDB introduces a different variable to control the MRR buffer… the access pattern will be. There is one MRR related variable introduced in MySQL 5.6 and MariaDB 5.5 Handler…
Comment: PHP Sessions - Files vs Database Based
April 10, 2012 By 38 Comments
… problem with concurrency between simultaneous requests overwriting each others $_SESSION variable. On a multi-frontend environment client’s rapid consecutive ajax… can be operated only as a single entity. It’s good for reliably locked simple single server installation, but not for distributed…
Comment: Introducing new type of benchmark
February 26, 2012 By 16 Comments
…. It just makes sens to apply it to databases too. . single-file serving is tested by setting a number of concurrent… a query-with-joins. Needless to say, there are many variables to take into account (size of data set, usage of…
Post: kernel_mutex problem. Or double throughput with single variable
December 2, 2011 By 17 Comments
…) has complex handling with spin loops, and there are two variables that affects mutex loops: innodb_sync_spin_loops and innodb…_wait_delay. I actually think that tuning system with these variable is something closer to dance with drum than to scientific….65 1024 22166.94 61507.08 So playing with this variable we can double throughput to the level with 32-64…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
… if you have really bulk inserts 100-1000+ values per single insert statement. concurrent_insert – Enables concurrent insert (while Selects are… but currently implemented only for Innodb. tmp_table_size This variable specifies maximum size implicit temporary table (created during query execution…
Post: MySQL Session variables and Hints
December 28, 2006 By 2 Comments
… FORCE INDEX(A) JOIN B The other part is session variable. If you know query is going to require large sort… production hints are used much more frequently than setting session variables for given query execution even though it also can be… I think would be to allow per session variables to be changed only for single query execution and returned to their old…
Post: How to recover a single InnoDB table from a Full Backup
January 25, 2012 By 7 Comments
… your tables. In this particular scenario is faster to recover single tables than a full backup. This is easy with MyISAM… of the table after the backup has been taken. The variable innodb_file_per_table must be enabled. Then, our first… back again! Conclusion: As we learned , you can also recover single InnoDB table as with MyISAM but knowing in advance that…
Comment: Three ways that the poor man's profiler can hurt MySQL
December 2, 2011 By 19 Comments
…/2011/12/02/kernel_mutex-problem-or-double-throughput-with-single-variable/ by the way, Vadim and I discussed and he did…
Post: Innodb row size limitation
April 7, 2011 By 11 Comments
… can’t store all of the variable-length columns for a given row on a single database page. Innodb has a limit… single row on a page. If your row has variable length columns and the complete row size exceeds this limit, InnoDB chooses variable… be the only possible solution. Combine all your variable length fields into a single BLOB and do the splitting at the application…
