Tag: query‑planning
It is time to resume the TPC-H series and look at Query 7. We will learn about how query optimisers can decompose filters and reason about the structure of expressions to reduce join This...
And now, for something completely different. This week on TPC-H query analysis - we are not going to look at join ordering. Today's query does not have any joins. But as we shall see, is to...
Welcome back to the TPC-H analysis. If this is your first time, I highly recommend that you visit the previous blogs in the series first. They're here (and I look forward to seeing you in a...
Today we are looking at a Q04 — which on the surface is similar to Q17. Like Q17, Q04 has a correlated subquery that can be de-correlated using a join. But sometimes, a regular INNER JOIN is...
I want to teach you an important skill that will serve your well as a database specialist. One blog entry is not going to be enough, but here is my goal: When you look at an SQL query in the you...
The great promise databases make to programmers is: "Tell me what you want and I will figure out the fastest way to do it." A database is a computer science engine — it knows and...
After the wonderful feedback on the previous blog about Iceberg - it is now time to switch gears. Databases are more than row storage engines. They are algorithm machines, helping that...
Our database journey makes a brief stop. We need to appreciate an important design decision every database must make: Should I use row or batch execution? Depending on the database - or...
If you ever looked at query plan from a SQL databases - you are likely to have come into something called "cost". You may even have heard that most advanced database use based a...