A la différence d’une procédure une fonction stockée est conçue pour retourner un résultat.
Replication enables data from one MySQL server, called the master, to be replicated to one or more MySQL servers, called slaves. Replication is mostly used as a scale-out solution. With scale-out solution we are basically spreading the load among multiple slaves to improve performance. In this solution, all writes and updates take place on the master server, while reads take place on one or more slaves. This model improves both the write performance as well as the read performance across an increasing number of slaves. This scale-out solution that I have discussed above is actually master-slave replication, and this is the kind of replication that we will be setting up today.
When we migrated to 64bit Debian Etch about two months ago we noticed that some of our database boxes were paging even though they had plenty of memory to perform the tasks at hand. The boxes had 8G and we told INNODB to allocate 7G to the buffer pool. The problem is that after using about 6G the machine would start to swap constantly. Swapping out 1G of ram to disk is NOT going to be fast. I couldn’t figure out what was going on.
Wednesday May 04, 2011 Finally, a Cure for Crap MySQL Performance on OS/X
November 3, 2007 By Peter Zaitsev 39 Comments My last post about Innodb Performance Optimization got a lot of comments choosing proper innodb_buffer_pool_size and indeed I oversimplified things a bit too much, so let me write a bit better description. Innodb Buffer Pool is by far the most important option for Innodb Performance and it must be set correctly. I’ve seen a lot of clients which came through extreme sufferings leaving it at default value (8M). So if you have dedicated MySQL Box and you’re only using Innodb tables you will want to give all memory you do not need for other needs for Innodb Buffer Pool. This of course assumes your database is large so you need large buffer pool, if not – setting buffer pool a bit larger than your database size will be enough.
Traditionally, the comparison between PostgreSQL and MySQL gets heated from both sides of the religious camps. They are both technically strong, open-source databases with a large install base. However, in reality, rarely do the strengths of each database overlap to an extent where it is a toss-up of which solution to use. Once people understand the strengths of each product, the choice is typically fairly clear. In order to properly evaluate the strengths of PostgreSQL and MySQL, let's look at the history and pedigree of each. Let's also look at their feature functionality and performance, as well as the requirements for a successful enterprise database deployment.
comments The SQL Server backup - foundation of any Disaster / Recovery by Ted Krueger (onpnt) on Jun 08, 2010 in categories Database Programming , Database Administration , Microsoft SQL Server Admin , Microsoft SQL Server