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Get valuable Virtual Log File (VLF) information for all your databases log files

Get valuable Virtual Log File (VLF) information for all your databases log files

I had this problem where I needed to gather Transaction Log information on multiple databases and check for valuable statistics on them. Running the command [DBCC Loginfo] brings back a number of rows for each Virtual Log File (VLF) in your Log File. It is really hard to do anything useful with that information on a larger scale. Each row returned gives you an estimate for the number of VLFs per Log File. Sure you could use the internal (and hidden) system stored procedure sp_msforeachdb to get the information for all database but it looks horrible. Here try it out for yourself before you read the rest of the post:


exec sp_MSforeachdb 'Use [?] select db_name(); DBCC LogInfo'

So why not make it better? That’s what I thought to myself, and I have recently been playing with storing DBCC command output to tables for analysis. I’ve put some together some code that allows you to capture the output of DBCC LogInfo into a Temp Table and then get some interesting information about the number of VLFs per database and other valuable information; see the comments for more information. Just by storing some of this data temporarily, I was able to write queries against it and discovered a major inconsistency in the size of my VLFs in a Log File that could potentially cause performance issues.

Feel free to create a permanent table for this data and run it on a regular basis to get an understanding of what your system is doing for troubleshooting. I also commented out the date field since I deemed it unnecessary, but if you’re looking for trending it maybe a good option to have that additional data.

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