… IO these should be 16K – page size, for full table scan or index scan read-ahead may be performed which can increase average… are pretty fast. ———————- BUFFER POOL AND MEMORY ———————- Total memory allocated 4648979546; in additional pool allocated 16773888 Buffer pool size 262144 Free buffers 0 Database pages 258053… buffer pool for new data – when previous page content was not read to the buffer pool. Finally you can see buffer pool hit ratio which measures buffer pool…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…buffer_pool_instancesblogpercona.commanual Innodb_buffer_pool_pages_datablogpercona.commanual Innodb_buffer_pool_pages_dirtyblogpercona.commanual Innodb_buffer_pool_pages_flushedblogpercona.commanual Innodb_buffer_pool_pages_freeblogpercona.commanual Innodb_buffer_pool…
Post: InnoDB: look after fragmentation
November 5, 2009 By 12 Comments
… on disk The problem is that after restoring table from mysqldump, the query that scans data by primary key was slow. How… sec) mysql> SHOW STATUS LIKE ‘Innodb_scan_pages%’; +——————————+——-+ | Variable_name | Value | +——————————+——-+ | Innodb_scan_pages_contiguous | 45 | | Innodb_scan_pages_jumpy | 35904 | +——————————+——-+ 2 rows… hurt your query significantly, especially when data is not in buffer_pool and execution goes to read from disk Fragmentation by secondary…
Post: Is there room for more MySQL IO Optimization?
January 3, 2013 By 11 Comments
… than buffer pool size and OS cache which is available. I run CHECK TABLE on this table which essentially performs data and indexes scan which… full table scan and index scan queries, though this is really not the point. The point is I have discovered with the buffered IO… double buffering as well as more information MySQL has about data which will be accessed next – in case of full table scan, index scans…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
…’ fits in 16 GB. I mean, if the database buffer pool can buffer many writes to the same page, then fewer disk writes… in my.cnf, to prevent double buffering. Configure as much memory as possible to InnoDB’s buffer pool. For this, you need to… 64 pages == 1 MB. Then a full table scan would be fast. Maybe the table has become fragmented? Or maybe you have not…
Post: How to estimate time it takes Innodb to Recover ?
May 9, 2007 By 7 Comments
… the database and may not be as buffer pool flushes are not predictable. As Innodb is scanning log files from last checkpoint time… update for relatively small table) less IO will be required as pages already will be in the buffer pool. I think the reason… – first if you have small buffer pool you will have a lot of pages being flushed from buffer pool and so you may end…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
… small table (200MB) which completely fits in the Innodb Buffer Pool (512MB). We also have larger table 4GB which does not fit in the buffer pool. We’re running uniform sysbench OLTP on the small table and mysqldump on the second table. First we run… see in default configuration MySQL has buffer pool which can be easily washed away by large table scans or heavy batch jobs. If this…
Comment: MySQL Server Memory Usage
September 1, 2006 By 21 Comments
…376′ ‘Sort_range’, ’56479689′ ‘Sort_rows’, ’1344092495′ ‘Sort_scan‘, ’935242′ ‘Table_locks_immediate’, ’895966639′ ‘Table_locks_waited’, ’20096′ ‘Threads_cached’, ’0′ ‘…var/log/mysql innodb_table_locks=0 innodb_buffer_pool_size=1800M # USE ALL MEMORY AVAILABLE #innodb_log_buffer_size=8M # Lowered…
Post: Returning to InnoDB scalability
July 28, 2006 By 42 Comments
… into problem: On 4-CPU box 1 thread executes full-table scan select query for 8 sec, but with 4 threads – each… which show the problem is with “buffer pool” mutex, which protects innodb_buffer_pool. In details, for each scanned row InnoDB calls block_get / block…_release use mutex_lock(buffer_pool_mutex) / mutex_unlock(buffer_pool_mutex) calls. So global mutex is accessed for each scanned rows, what in multi…
Post: How innodb_open_files affects performance
November 18, 2009 By 4 Comments
… in innodb buffer pool which had to be flushed before recycling. First ran however was done with clean buffer pool (after reading all tables once… half-written data pages from the doublewrite InnoDB: buffer… InnoDB: Doing recovery: scanned up to log sequence number 12682768136 091118 18:47…
