…gain, as to update we need to read data, and in this case – read previous comment. – The version we … is not fully transparent backup, as it applied TABLE LOCK on copying table. When recovery logs are supported, …6.0, but I can’t yet say how it will work with mix of storage engines. – The Tokutek …
Comment: Are PHP persistent connections evil ?
November 14, 2008 By 32 Comments
… mySQL, the use of SELECT FOR UPDATE and SELECT LOCK IN SHARE MODE, How to use it? They don’t make any sense to me in a web application, because when you first read the… the same link resource to UPDATE and then COMMIT, or how does it works?
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… enough, there was some work done by DIKU students improving algorithms used for read ahead and results were… level READ COMMITTED, then InnoDB normally does not lock the ‘gaps’, and it does not lock rows … causing problems every so often. Q16: How Innodb decided how many pages to flush at each …
Post: INSERT INTO ... SELECT Performance with Innodb tables.
July 12, 2006 By 22 Comments
… INTO table1 SELECT * FROM table2. This statement will perform locking read (shared locks) for table2 table. It also applies to similar tables with… to know it had to be done fore replication to work right in MySQL before 5.1. In MySQL 5.1… tests to see how well it performs 
One more thing to keep into account – INSERT … SELECT actually performs read in locking mode and…
Post: DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
… give a high level picture of how Lazy Drop Table works and how the new DROP Table works in MySQL >= 5.5.23. After….5.23 work, I would like to mention quickly, that how drop table in MySQL < 5.5.23 used to work. When dropping…. However, a lock on the AHI latch can cause contention for writes, since its a shared lock, so while read queries can still…
Post: Test Drive of Solid
September 22, 2006 By 5 Comments
… would expect from repeatable-read isolation mode, at least in its interpretation by Innodb. Let’s look how PESIMISTIC works (mysqld started with… seems to work in some cases. However behavior is different from Innodb which will do READ-COMMITED for locking reads (SELECT FOR UPDATE/LOCK IN…
Post: Modeling MySQL Capacity by Measuring Resource Consumptions
March 8, 2011 By 1 Comment
…level locks. There is also a load aspect – “random arrivals” tell us the number of work system has…Thinking Clearly About Performance by Cary Millsap. So how we can use this data to estimate … ROWS_FETCHED: 485139 ROWS_UPDATED: 0 TABLE_ROWS_READ: 610954 SELECT_COMMANDS: 181243 UPDATE_COMMANDS: 0 OTHER…
Post: Falcon Storage Engine Design Review
January 12, 2007 By 19 Comments
… got them while working for MySQL. These thought base on my understanding, reading docs, speaking to Jim,… not use Spinlocks. It has its own lock implementation which does operation system wait if …. This would be very interesting to see how these optimizations will show themselves in practice. …
Post: Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks
August 17, 2012 By 17 Comments
… to go gain every lock on every node you need for all running transactions. How would deadlock detection work? On a single node, a deadlock is fairly easy to see by looking at all transactions waiting for locks and… read view will not see trx with id >= 83C, sees < 83C TABLE LOCK table `test`.`autoinc` trx id 83B lock mode IX RECORD LOCKS…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
… configuration you can’t assume locking table for write will mean no one will be able to read it – results still can… as a lot depends on statement complexity as well as how much work is saved by query cache. Now lets speak a… can’t change how it works with MySQL to add caching but you can enable query cache so it works faster. Low load…
