FusionIO and the Go Faster Button

Nobody has ever said that FusionIO cards were slow (because they aren’t). Especially if you compare their performance to regular spinning media, or high performance SANs. After all, no SAN will allow you to measure storage write latency in microseconds.

Anyone that has had their database reside on a FusionIO card has had nothing but good things to say about them. The only thing is that a lot of people are probably not making the most out of the cards that they have. FusionIO cards actually have an artificial performance restriction put on them, and can go even faster than they do now.

Continue reading

Improving Performance When Querying Multiple DMVs

A couple of days ago I posted a stored procedure (sp_GetAGInformation) which queried multiple DMVs to pull together a bunch of AvailabilityGroup information. If you took a look at the code you would see that it used a couple of CTEs (Common Table Expressions).

CTEs are a great way to do recursive work, and they can also greatly simplify reading code. A CTE without recursion is really nothing more than a subquery that is nicely wrapped.

For example:

Basic+CTE

Basic CTE

Is the same thing as:

Basic+Subquery

Basic Subquery

This can easily lead you down the path towards poor performance. It is quite easy to define a CTE once and use it multiple times, not realizing that every time you use the CTE then you are performing that subquery, meaning is has to be evaluated and executed.

For smaller queries this is not usually a problem, but for larger queries and more importantly when working with DMVs this can be a serious performance problem.

Continue reading

sp_GetAGInformation – Updated

Yesterday I posted sp_GetAGInformation, a stored procedure for gathering information about configuration of Availability Groups. Based on feedback I’ve added an additional column to indicate the health state of the AG.

download

 

Download the updated version for this additional information.

© 2015 SirSQL

Theme by Anders NorenUp ↑