May 24, 2012

Comment: Testing Samsung SSD SATA 256GB 830 - not all SSD created equal

…-only case closely following the writes? GC normally runs at low priority and can continue for hours. It usually tries to run…

Post: Using MyISAM in production

… enough. Lock priorities. By default MySQL treats updates as higher priority operations. You can use SELECT HIGH_PRIORITY or UPDATE LOW_PRIORITY to adjust that or you can simply set low_priority_updates option…

Post: Ultimate MySQL variable and status reference list

…_tc_sizeblogpercona.commanual log_warningsblogpercona.commanual long_query_timeblogpercona.commanual low_priority_updatesblogpercona.commanual lower_case_file_systemblogpercona.commanual lower_case_table….commanual sql_log_offblogpercona.commanual sql_log_updateblogpercona.commanual sql_low_priority_updatesblogpercona.commanual sql_max_join_sizeblogpercona.commanual sql_modeblogpercona.commanual…

Comment: Linux IO Schedulers and MySQL

… is tough to use with database as there can be priority inversion due to lock held by the thread etc. What… great to see implemented is per request priorities so log flushes for example would get high priority while background dirty pages flush low priority.

Post: SELECT LOCK IN SHARE MODE and FOR UPDATE

… on Innodb table but no updates. Supporting MySQL hints “HIGH_PRIORITY” and “LOW_PRIORITY” would probably be good start.

Post: MySQL Server Variables - SQL layer or Storage Engine specific.

… Cache also could use this feature. low_priority_updates If enabled selects will get higher priority than updates and waiting update will not…

Comment: Percona build7 with latest patches

… MySQL 32bit) [mysqld] max_connections=2000 key_buffer_size=200M low_priority_updates=1 table_cache = 8000 sort_buffer_size = 2097152 innodb…

Comment: Living with backups

Using bandwidth limit in rsync or compression speed (with low priority) as a way to offload the system is a good …

Post: Concurrent inserts on MyISAM and the binary log

… gets a lock on the table like this: Locked – read Low priority read lock But on INSERT…SELECT, you’ll see this…

Comment: Managing Slave Lag with MySQL Replication

Setting LOW_PRIORITY on UPDATE/DELETE/INSERT queries may also cause a replication lag. It works fine on the master, but when it is being replicated to the slaves, it will cause the replication thread to wait until there are no more readers on that table.