Video: three SQL Server join operators in three minutes

In an attempt to try a different approach, here’s a three-minute video explanation of how the different physical join operators in SQL Server work and why you would choose one over the other.

More reading

I’ve written a few blog posts on join operators befores, so if this video wet your appetite, here’s some recommended reading:

I’d love to hear what you think of the short video format! Please leave feedback in the comments below or on Twitter.

Different query plans for “OR” type queries

The SQL Server query optimizer can find interesting ways to tackle seemingly simple operations that can be hard to optimize. Consider the following query on a table with two indexes, one on (a), the other on (b):

FROM #data
WHERE a<=10 OR b<=10000;

The basic problem is that we would really want to use both indexes in a single query.

In this post, we’re going to take a look at a few examples of how this type of query would be optimized, as well as how statistics can affect the query plan, and finally, we’ll take a look at a slightly rare plan operator called “Merge Join (Concatenation)”.

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