I mentioned in my last post in this series, that the Compute layer of Snowflake is basically made up of a series of Virtual Warehouses (VWs). Each VW is an MPP (massively parallel processing) compute cluster that can comprise one or more compute nodes.
The number of nodes in the compute cluster is called its “size” and the sizing options are made to resemble T-Shirt sizing, as you can see in the main image above.
2019-08-30
In a recent post, I wrote how the T-SQL TRIM() function was more than just an LTRIM(RTRIM()) and that it took me a while to realize that. Well today, I found another one that I hadn’t noticed before: EOMONTH.
I was writing a SELECT clause for a query, when the Intellisense popped up:
And suddenly I noticed “Param2” and wondered what on earth the second parameter was.
Now you might notice that the Intellisense isn’t very helpful on this. It gives you no hint what the parameters are. In fact, for many of the features added to T-SQL in SQL Server 2012, the Intellisense is really poor. Here’s another example:
2019-08-29
When I’m working with dates, I often need to calculate how many days there are in a specific date.
So, in our free SDU Tools for developers and DBAs, we added a simple tool that does just that. It’s called DaysInMonth.
It takes one parameter:
@Date date - the date to check
Nothing complex. It takes a date, and returns the number of days in the month that contains that date.
2019-08-28
There’s a well-known effect that’s often described in physics as the Observer effect. The argument is that whenever you measure things, you invariably alter them. The simple example given in Wikipedia is that it’s pretty hard to check the pressure of a tire (tyre) on a car, without letting at least some air out.
The same effect also happens in IT systems. A simple example is that to observe something, you might add logging or auditing, and the work to output those slows down the primary work that you are doing.
2019-08-27
In my last T-SQL 101 post, I mentioned that GO was just a word that’s used to separate batches. In fact, it’s not a SQL word at all. If you actually send the word GO to the server, it wouldn’t know what you’re talking about.
I mentioned that the word is only understood by the program that you type the script into. SSMS also allows us to make use of another additional trick in relation to GO.
2019-08-26
The first thing to understand about Snowflake is that it has a very layered approach. And the layers are quite independent, including how they scale.
The lowest level isn’t part of Snowflake; it’s the services that are provided by the underlying cloud provider. As a cloud native application, Snowflake is designed to use services from the cloud provider that they are deployed to, rather than providing all the services themselves. At present, that means AWS or Microsoft Azure. Deployment on Google’s cloud platform is in preview at this time.
2019-08-22
In SQL Server, both logins (access to the server) and users (access to a database) have a name and a security ID (SID). This leads to problem situations where names might match but SIDs don’t match.
I’ve lost count of the number of times I’ve seen a user restore a database from another server, and then realize that the SQL Server login they need wasn’t present. Then, they create a new login and end up in a lousy situation, because the new login’s SID doesn’t match the SID of the user in the database. I call this a mismatched SID issue.
2019-08-21
The image below shows a T-SQL script.
It’s an example of contents of a file that you could have on your disk so the entire thing could be called MyProgram.sql. Inside this script file, we’ve got a few different types of things happening here.
The word script applies to all of the contents of the file.
You can see the word GO there a number of times. It’s a special word that’s not actually a T-SQL keyword. It’s a batch separator. It only has meaning to the tool you’re using to execute queries, like SQL Server Management Studio or Azure Data Studio.
2019-08-19
If you ask SQL Server developers how to calculate the length of a string in T-SQL, most would tell you immediately that you need to use the LEN() function. What most don’t realize though, is that it doesn’t actually work properly.
The T-SQL LEN() function ignores any trailing spaces in a string.
That’s not how a string length function should work, or how it works in most languages. So, in our free SDU Tools for developers and DBAs, we added a simple tool that works properly. It’s called StringLength.
2019-08-15
In recent years, I’ve done a lot of work in software houses (Microsoft calls them ISVs or Independent Software Vendors). Many of these software houses have worked out that they won’t be able to just keep selling their on-premises applications because their customers are asking for cloud-based solutions.
And more importantly, the customers want the software houses to manage the applications rather than themselves. So, many of the software houses start trying to turn their on-premises applications into Software as a Service (SaaS) applications.
2019-08-15
