Need’em Got’em
Let’s say you’ve either got a heap, like we talked about yesterday, or you’re plotting a new table.
It’s OLTP, and you want the very best for your transactions. What are some good characteristics of a clustered index?…
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The Trillion Row Operator
SQL Server friend and excellent webmaster Mr. Erik C. Darling showed me a query plan gone wrong:
48 billion rows for a single operator is certainly a large number for most workloads. I ended up completely missing the point and …
Starting SQL: Quick Notes About Heaps
Nein Nein Nein
I know, I said we’d talk about indexes, and heaps are basically the opposite of indexes.
Even if you have a heap with a nonclustered primary key, or nonclustered indexes hanging around, the base table is …
Starting SQL: A Little TOP Can Have A Big Sort
Shortcuts
To illustrate this problem a little bit better, I need to use a slightly different query.
While a tidy group by was nice to illustrate some of the simpler points about lookups, it overly complicates things when we want …
Starting SQL: Why Didn’t You Use My Index?
What’s With Widths?
We don’t need to add a ton of columns to our query to have index usage change, but we do need to go back in time a little bit.
Here’s our query now, with just a one …
Starting SQL: Messing Up A Query
Your Fault
Yesterday we created an index, and things went pretty well. Good for us. By next week we’ll have six pack abs.
Today we’re going to look at things that I see happen pretty often in queries that mess …
Starting SQL: Measuring A Query
Outlaw Buttons
Yesterday, we started with a query, and wanted to add an index to make it faster. Remember, indexes help queries find and relate data by putting it in order.
In the weird old days, we might use SET …
Starting SQL: Indexes Store Data In Order
Index Skit (0:39)
The most common types of indexes you’re going to see in your life are of the rowstore variety.
As much as I love columnstore, it’s probably not something you’re going to see a whole lot outside of …
Starting SQL: Written Queries vs Executed Queries
You Know You Wanna
Every time you push F5, decades of research, code, and math kick in and have their way with your query. No, really. They do.
Your query is a question that the database has to answer, and …
Starting SQL: A Month Of Fundamentals Posts
Unlearninging
I’m going to be taking a break in August, but I still want the Blogs To Flow™ while I’m letting my brain meat get its groove back.
So this month I’m going to run some fundamentals posts that I …