What are the Magical Clocks for?
At Re:Invent last week, AWS announced DSQL, their new serverless SQL database. As a fan of distributed SQL databases I have been enjoying reading about the...
Thoughts on DuckDB's Grammar Patching Thing
It is the job of modern programming languages to be amenable to abstractions. It should be easy for users to take a little bundle of functionality and reuse...
Fine! I'll Play With Skiplists
Follow me on Bluesky! A Log-Structured Merge tree, or LSM, is a popular data structure for storage engines. It’s what is used by RocksDB, which is sort of...
The Prequel to SQL is SEQUEL
Meta note: follow me on Bluesky if you are so inclined. I've been going through some historical stuff lately. Been on a history kick. We went to see the...
The CVM Algorithm
Everything you need to know about query planning can be understood from this query: SELECT * FROM xy WHERE y = 3 ORDER BY x Imagine we have two indexes, one...
How Many Grains of Sand are in a Pile
“This code’s no good,” says Pittsford, pointing at the screen: def update_and_get_balance(account, amount): database.debit(account, amount) return...
Adventures in Probability
I hope everyone had a good weekend. I went on a hike. It was great. Statistics One of my great school regrets, next to “taking three years of business...
Pushing Values to Zero
There is a popular presentation of the exponential distribution that goes through the geometric distribution. The geometric distribution arises from flipping...
Linearity in Query Processing
I saw a fun post this week about interpreting colours as vectors and the way you can exploit that interpretation to nicely represent certain operations you...
The Relational Derivative Pt. 2: Groups are Good
Last week we talked about the notion of the relational derivative and its application to enforcing integrity constraints in databases. The relational...
Integrity Constraints and the Relational Derivative
In a SQL database, you can set up a foreign key with REFERENCES: nullbitmap=# CREATE TABLE ab (a INT PRIMARY KEY, b INT); CREATE TABLE nullbitmap=# INSERT...
The Two Machines
There's a joke in my friend circle that asks "is it a database?" A startup, a program, a syscall, a person good with numbers, a person with a good memory....
Benchmarks That Aren't Your Friends
We’ve now talked twice about an important dimension of a benchmark: the openness of the loop. While there’s more subtlety to it, if what you take away is:...
Measuring Throughput
Note: I'm trying out enabling comments. Behave! I reserve the right to disable them again for any reason including "the very idea of someone commenting made...
SQL's Grammar Ambiguity
I was going to write a longer, more involved post this week, but I wound up getting Covid and didn't have it in me to work through all the stuff I had to for...
Languages Without Abstraction
Implementing something like a compiler, there is the understanding that we want different representations of a program for different purposes. This is why we...
The Closed-Loop Benchmark Trap
Let's make a little mock database. It won't actually do anything but pretend to handle requests. I've had cause at work lately to write some Go so we're...
Some Books I Like // One Year of NULL BITMAP
This is the 52nd NULL BITMAP, which means I have been doing this for a whole year! I skipped one week before I decided that this was going to be a weekly...
Solving Rubik's Cubes with Computers
The first place I got into programming was making games. You can probably dig up some games I made long ago if you try hard enough (do not). In high school,...
What do we want? Negation! When do we want it? Not later!
Hello I am traveling this weekend! I am home in Ontario. I wanted to share this picture I took of this guy feeding a bear. Bear eating an object out of a...
