One of the biggest and undead myths in SQL is that COUNT(*) is faster than COUNT(1). Or was it that COUNT(1) is faster than COUNT(*)? Impossible to remember, because there's really no reason at all why one should be faster than the other. But is the myth justified? Let's measure! How does COUNT(...) work? But … Continue reading What’s Faster? COUNT(*) or COUNT(1)?
Tag: mysql
The Cost of Useless Surrogate Keys in Relationship Tables
What's a good natural key? This is a very difficult question for most entities when you design your schema. In some rare cases, there seems to be an "obvious" candidate, such as a variety of ISO standards, including: ISO 639 language codesISO 3166 country codesISO 4217 currency codes But even in those cases, there might … Continue reading The Cost of Useless Surrogate Keys in Relationship Tables
How to Reduce Syntactic Overhead Using the SQL WINDOW Clause
SQL is a verbose language, and one of the most verbose features are window functions. In a stack overflow question that I've encountered recently, someone asked to calculate the difference between the first and the last value in a time series for any given day: Input volume tstamp --------------------------- 29011 2012-12-28 09:00:00 28701 2012-12-28 10:00:00 … Continue reading How to Reduce Syntactic Overhead Using the SQL WINDOW Clause
JOIN Elimination: An Essential Optimiser Feature for Advanced SQL Usage
The SQL language has one great advantage over procedural, object oriented, and "ordinary" functional programming languages. The fact that it is truly declarative (i.e. a 4GL / fourth generation programming language) means that a sophisticated optimiser can easily transform one SQL expression into another, equivalent SQL expression, which might be faster to execute. How does … Continue reading JOIN Elimination: An Essential Optimiser Feature for Advanced SQL Usage
jOOQ 3.10 Supports Exciting MySQL 8.0 Features
In recent months, there had been some really exciting news from the MySQL team: (Recursive) Common Table Expressions in MySQL Introducing Window Functions These two SQL standard language features are among the most powerful SQL features that are available from most other databases. I frequently include them in conference talks about SQL (see my article … Continue reading jOOQ 3.10 Supports Exciting MySQL 8.0 Features
How to Execute SQL Batches With JDBC and jOOQ
Some databases (in particular MySQL and T-SQL databases like SQL Server and Sybase) support a very nice feature: They allow for running a "batch" of statements in a single statement. For instance, in SQL Server, you can do something like this: -- Statement #1 DECLARE @table AS TABLE (id INT); -- Statement #2 SELECT * … Continue reading How to Execute SQL Batches With JDBC and jOOQ
The 10 Most Popular DB Engines (SQL and NoSQL) in 2015
About two years ago, we've published this post about the 10 most popular DB engines, where we analyzed the data published by Solid IT on their DB Ranking website. In the meantime, the Solid IT measurement system has found to be a credible source, such that the website has also been cited at Gartner, InfoWorld, … Continue reading The 10 Most Popular DB Engines (SQL and NoSQL) in 2015
Use MySQL’s Strict Mode on all new Projects!
MySQL is a database that has been bending the SQL standard in ways that make it hard to move off MySQL. What may appear to be a clever technique for vendor lockin (or maybe just oversight of the standard) can be quite annoying in understanding the real meaning of the SQL language. One such example … Continue reading Use MySQL’s Strict Mode on all new Projects!
Don’t Migrate to MariaDB just yet. MySQL is Back!
Now that I have your attention, I'd like to invite you to a critical review of where we're at in the MySQL vs. MariaDB debate. Around one month ago, I visited Oracle Open World 2014, and I've met with Morgan Tocker, the MySQL community manager at Oracle to learn about where MySQL is heading. Who … Continue reading Don’t Migrate to MariaDB just yet. MySQL is Back!
Frightening Facts about MySQL
So you might've seen Destroy all Software's talk about JavaScript: Here's a similar talk (less funny more scary) about MySQL: https://www.youtube.com/watch?v=emgJtr9tIME