The latest from the MySQL community

Other day we had a small discussion about data stores and hardware; and which one drives the other when it comes to data storage solution, rather it is a hard discussion as both on its own are bigger entities; and one can not easily conclude as it depends on use cases and actually speaking data [...]

Very nice and interesting post from Michael Stonebraker explaining how errors dictate CAP Theorem (Consistency, Availability and Partition-tolerance); as only one objective from the CAP can be achieved during normal error conditions as NoSQL system seems to relax the consistency model as CAP theorem anyway proves that one can’t get all 3 at the same [...]

Here is some file IO performance numbers from DELL MD1120 SAS storage array. Last year I did the same test with HP P800 storage array and numbers were impressive. But when it comes to this high end storage array, few surprises.  Before getting into actual details; lets see the test stats and configuration details. System Configuration:

DELL [...]

Its been a while anyone talked about Intel’s Hyper-Threading performance when it comes to databases. There were enough posts about disabling Hyper-Threading  completely when it comes to MySQL/InnoDB workloads way back when we had enough issues with scalability of InnoDB on multi-core systems. But things has changed quite a bit in the fast year or [...]

This is the 182nd edition of Log Buffer, the weekly review of database blogs. Make sure to read the whole edition so you do not miss where to submit your SQL limerick!

This week started out with me posting about International Women’s Day, and has me personally attending Confoo (Montreal) which is an excellent conference I hope to return to next year. I learned a lot from confoo, especially the blending nosql and sql session I attended.

This week was also the Hotsos Symposium. …

By default InnoDB uses REPEATABLE READ as its isolation level. So this is the isolation level used with innoDB by almost all MySQL users.

The default isolation level of Oracle is READ COMMITTED. READ COMMITTED is the mode widely used by Oracle users. This mode incurs less penalty on the server scalability by allowing to [...]

In MySQL 6.0 a threadpool design was implemented based on
libevents and mutexes.

This design unfortunately had a number of deficiences:
1) The performance under high load was constrained due to a global
mutex protecting libevent (see BUG#42288).

2) The design had no flexibility to handle cases where threads were
blocked due to either locking or latches. E.g. a thread held up by a
table lock will be kept in the threadpool as an active thread until
the table lock is released. If all threads are blocked in this state,
it's easy to see that also any query that want to release the table
lock cannot be processed since all threads in the thread pool are
blocked waiting for the table lock (see BUG#34797).

3) The design is intended to support very many connections but
didn't use the most efficient methods to do this on Windows.
…

This past week I have been working with 2 Web2.0 startups - members of Sun Startup Essentials, they get the support for free - that are looking at improving the response time of their web site.

We've been working at understanding how they servers behave today and what could prevent their application to scale, which led me to show how to run a quick diagnostic on an existing system and to restate some key fundamentals in terms of scalability.

Let's start by the fundamentals.

Any piece of software is nothing else than a set of instructions that need 2 things: computing units to execute on, and a fast access to data.

Computing units are available in the form of a hardware threads located on a processor. The number of threads that a server makes available to the application depends on the number of processors on the server, the number of …

This past week I have been working with 2 Web2.0 startups - members of Sun Startup Essentials, they get the support for free - that are looking at improving the response time of their web site.

We've been working at understanding how they servers behave today and what could prevent their application to scale, which led me to show how to run a quick diagnostic on an existing system and to restate some key fundamentals in terms of scalability.

Let's start by the fundamentals.

Any piece of software is nothing else than a set of instructions that need 2 things: computing units to execute on, and a fast access to data.

Computing units are available in the form of a hardware threads located on a processor. The number of threads that a server makes available to the application depends on the number of processors on the server, the number of …

This past week I have been working with 2 Web2.0 startups - members of Sun Startup Essentials, they get the support for free - that are looking at improving the response time of their web site.

We've been working at understanding how they servers behave today and what could prevent their application to scale, which led me to show how to run a quick diagnostic on an existing system and to restate some key fundamentals in terms of scalability.

Let's start by the fundamentals.

Any piece of software is nothing else than a set of instructions that need 2 things: computing units to execute on, and a fast access to data.

Computing units are available in the form of a hardware threads located on a processor. The number of threads that a server makes available to the application depends on the number of processors on the server, the number of …