A Fine Slice Of SQL Server
You would think base R would have a count function such as count(df$Team) and count(df$Team == “NYY”) but this gives the error “could not find function ‘count’”. Base R does not have a count function. Base R has at last four ways to perform a count:
Click through to learn the different ways available to you, including those built into R itself as well as other packages like dplyr. H/T R-Bloggers.
Lee Markum has seven lessons for us:
SQL Server indexing basics are critical to query and server performance. Resources, like CPU and disk, are affected by the indexes that you have, or the ones you’re missing.
In the StackOverflow2013 database we’re going to look at Badges and users. Specifically, I want to start by seeing what badges a user has and when that user received them. Some badges, because of the type of badge it is, can be awarded more than once.
Click through for a demonstration.
Comments closedSabyasachi Samaddar walks through what I consider a real difficulty:
It is really challenging when you need to install third-party .whl packages into a DEP-enabled Azure Synapse Spark Instance.
According to the documentation, https://learn.microsoft.com/en-us/azure/synapse-analytics/spark/apache-spark-azure-portal-add-librar… Installing packages from PyPI is not supported within DEP-enabled workspaces. Hence we cannot just upload the .whl packages into the workspace. We need to upload all the dependencies along with the .whl package and it will be an offline installation. Now Synapse spark clusters come with in-built packages and hence we may find some conflicts when we try to install some third-party packages.
Read on to see what you need to do.
Comments closedGarry Bargsley can’t wait to truncate:
Today, I will discuss a gotcha I ran across with SQL Server Temporal Tables. In my day-to-day environment, we do not use Temporal Tables widely. However, a few are in use, and a few are coming down the pipeline for new projects.
Click through for the gotcha, as well as how you can work around the issue.
Comments closedKevin Hill has a video for us:
If you need to find the SQL Server ErrorLog in a hurry and don’t want to spend 30 minutes drilling into every drive on the server:
Fortunately, Kevin has anticipated me and has put together the “I don’t watch videos” version.
1 CommentAlex Crampton explains how snapshot fact tables work in data warehousing:
The typical fact table measures activities and is known as a transaction fact table. They support a wide variety of analytic possibilities and can be used to capture detailed information about a particular process. Certain facts cannot be studied easily using this kind of design, if at all.
This blog will outline the characteristics of a transaction fact table vs those of a snapshot fact table, and when the need for a snapshot fact table arises.
Snapshot-based fact tables aren’t ideal for data load times (especially as the table gets large) but they are useful in specific circumstances, as Alex points out.
Comments closedChad Callihan doesn’t make two calls:
Are you familiar with the OUTPUT clause in SQL Server? It can be used with commands like INSERT, UPDATE, DELETE, and MERGE. It can also be used with setting variables in stored procedures. Using the tried and true StackOverflow2013, we’ll narrow it down today to focus on how INSERT/DELETE are typically used for logging table changes as well as an example of how to use OUTPUT with stored procedures.
For really busy transactional systems, this provides a nice boost over making an update and then selecting the new values.
Comments closedRobert Cain has a post dedicated to the strcat() function in KQL:
The
strcatfunction has been shown in previous articles, but it’s so useful it deserves a post all of its own.As usual, the samples in this post will be run inside the LogAnalytics demo site found at https://aka.ms/LADemo. This demo site has been provided by Microsoft and can be used to learn the Kusto Query Language at no cost to you.
Read on to (re-)learn the power of string concatenation, in Kusto form.
Comments closedJohn Cook asks which is clearer, 1 or 2? 3 or 4? 4 or 6?
One problem with A/B testing is that your results may depend on the order of your tests.
Suppose you’re testing three options: X, Y, and Z. Let’s say you have three market segments, equal in size, each with the following preferences.
This is known as the Condorcet paradox of voting.
John also introduces the problem of interaction effects:
Suppose you’re debating between putting a photo of a car or a truck on your web site, and you’re debating between whether the vehicle should be red or blue. You decide to use A/B testing, so you test whether customers prefer a red truck or a blue truck. They prefer the blue truck. Then you test whether customers prefer a blue truck or a blue car. They prefer the blue truck.
Maybe customers would prefer a red car best of all, but you didn’t test that option. By testing vehicle type and color separately, you didn’t learn about the interaction of vehicle type and color.
Click through for both posts as well as some good insights.
Comments closedIt’s time to look back at the 155th blog party. I was the host this month, asking about Dynamic SQL. I got quite a few responses, which I’ve gone through and summarized below. If I’ve missed someone, please ping me.
Read on for a variety of thoughts on the topic.
Comments closed