Baron Schwartz

The Left-Prefix Index Rule

02/05/19 There’s an important heuristic in database indexing that I call the left-prefix rule. It helps you understand whether the database will be able to make the best use of a m…

Covering Indexes in MySQL, PostgreSQL, and MongoDB

02/01/19 A covering index is a fantastic query performance optimization. An index covers a query when the index has all the data needed to execute the query, so the server can retr…

The Iron Triangle of Sorting, Indexing, and Temporary Storage

01/30/19 Databases have a kind of iron triangle for specific types of query plans, whereby they can pick between two out of three things but can’t get all three of them. (The “iron…

What Is Concurrency in a Database?

01/28/19 Databases are confusing! Not only are they complicated bits of software, but database jargon is really complicated. Part of this comes from the number of words with multip…

Your ORM and SELECT FOR UPDATE

01/23/19 What’s an ORM? If you’re not familiar with ORMs, an ORM is an Object-Relational Mapper, which helps you map objects in your code to tables in your database, without writin…

The Difference Between Lock Wait Timeout and Deadlock

09/12/18 If you use ACID transactional databases, you’ve probably heard of lock wait timeouts and deadlocks. What are these? And how are they different? Inevitably, many of us will…

What Is Cardinality in Monitoring?

07/30/18 I wrote a couple of “definitions and nuances” posts about terminology in databases recently (cardinality, selectivity), and today I want to write one about cardinality in …

What is Database Index Selectivity?

07/18/18 I wrote recently about database cardinality, and there’s a closely related topic that is equally confusing and I want to explain too: index selectivity. Index selectivity …

The High Cost and Low Benefit of Unused Index Advice

04/26/18 You have to be careful what you wish for. The signal:noise ratio of finding out which indexes are “unused” is low. This isn’t obvious at first glance, but upon deeper insp…

2017 Year in Review for SolarWinds Database Performance Monitor

01/04/18 It’s easy to observe (pun intended) in the rear-view mirror. Hindsight bias aside, 2017 was a big year for SolarWinds Database Performance Monitor (DPM) and our customers!…

Monitoring, Analytics, Diagnostics, Observability, and Root Cause Analysis

12/03/17 Monitoring is a hopelessly overloaded term in tech culture. The term now carries decades of inaccurate and imprecise use. The result is that several people can be engaged …

Hierarchical Observability with RED

11/07/17 I’ve written before about the minimal set of metrics that can serve effectively as application/service vital signs. One such set is the RED acronym, which stands for Reque…