Category Archives: MS SQL Server 2016

Remove Numbers from Text SVF, Nested vs CTE

I need to remove numbers from a string while processing some data  as part of an ETL process in a data warehouse.  I have to do this for many columns and potentially many tables so I decided to put the logic into a Scalar-Valued Function (SVF), understanding there are performance detriments when using SVFs. Generally this will be used on relatively small data sets for cleaning “codes” that will be insert into a slowly changing dimension.  I was curious about how to do this.  My instinct was to do it using nested replace functions.  I did a quick google search to see what options the collective would recommend.  I came across a post on Stack Overflow that mentioned the nested replace functions, and then someone also mentioned using a recursive Common Table Expression (CTE), which I thought was a creative suggestion.

I have a soft spot in my heart for recursive CTEs so I thought I’d try both options and see which solution performs better.  Let’s start with building the functions:

Now that we have some functions we need some test data so let’s create a simple table and populate it with simi-random data by leveraging the newid() function.

Continue reading Remove Numbers from Text SVF, Nested vs CTE

Backup Transaction Logs to Nul for All Online Databases

First of all, never use this in a production environment!   This script is to backup your transaction logs to a “nul device” for all online databases which are not using simple recovery model.  In windows it is indeed spelled “nul” with one “L”.  The only reason you would want to do this is if you have a non production environment using full recovery model and this server architecturally mirrors your production environment.  For example, we have a “staging” server that is used for testing our code changes before they go into production.  We require the staging environment to be as close to production as possible and have scheduled scripts that sync them weekly.  In this scenario, we have many databases in the staging server that are using full recovery model but we do not want to backup the t-logs, we would rather just throw them away.

To learn more about NUL devices, here’s a link to the wikipedia page:

Resolve SQL Server Fatal error: cannot create ‘R_TempDir’

I was trying to test an install of R in SQL Server 2016 and when running a script I received this error: Fatal error: cannot create ‘R_TempDir’

Following the instructions here, I enabled external scripts, restarted the sql server service, and then tried to run the following test script:

This is when the fatal error occurred.  As the error suggests, R is having some issues creating a temporary directory.  After some internet searching and trial and error I got past the issue.

Enable  8dot3 File Names

R configuration uses the 8dot3 file name convention, also known as “short names”.  To enable this on windows 10, run the following command in CMD (command prompt):

For more options and information look here:

Give access to the working directory to R

Locate and open “rlauncher.config” file in a text editor.  This file will be under the “<sqlserver_instance>\binn” directory.  Take a look at the location of WORKING_DIRECTORY.  This should have a “short name” file path.  The path should be something like “<sqlserver_instance>\EXTENS~1”, and “\EXTENS~1” is equivalent to “\ExtensibilityData”.  We need to give access to R to this folder. I did this by changing the permissions to full control to everyone.  You may want to be more restrictive here, but in my case this did not matter.

  • Right click folder > Properties > Security tab > Advanced > Add
  • Select a principal (I entered “Everyone”)
  • Tick “Full control” under basic permissions and click “OK”
  • Tick “Replace all child object and permissions entries with inheritable permissions entries from this object” and click “OK”

Now if you rerun the script above you should get a result of “hello, 1”.