Viewing profile — RMarcus

You can also interpret each value in Perlin noise as a vector in a flow field to make some interesting and smooth animations reminiscent of older MacOS desktop wallpapers: https://…

I've got emacs keybinds in my muscle memory and Zed works well for me, although there's no kill ring and the macro system is nothing like emacs. The former will be added at some po…

This is awesome, thanks for creating this. I've had to write some absolutely wonky scripts to dump a PostgreSQL database into Parquet, or read a Parquet file into PostgreSQL. Norma…

Looks like he got a master's degree from UIUC and did some research on FFT implementations. Seems to have been successful. What makes you say he was 'considered a "bad student"'? (…

Depends! If you double the number of keys and you double the number of bins (load factor stays constant), then the problem becomes much worse very quickly. If you double the number…

This is my post from 2018 (I didn't submit it to HN), and it could definitely use a "here's what practical systems do" update! I'll put it on the TODO list... Your point about syst…

I'm curious to hear a bit more of your opinion. For example, I'm surprised that syscall latency is something near the top of your list. I think the usual wisdom in the DB community…

PostgreSQL has coarse-grain query hints (like `enable_hashjoin`), and the excellent `pg_hint_plan` extension allows you to specify a complete or partial execution plan: https://git…

It is certainly possible that the plans are similar, and that improvements to the execution engine are being measured. The join order benchmark was designed to test optimizer quali…

I totally agree -- I picked the latest version for each major version using the semver interpretation of the version numbers, which is not how PostgreSQL has traditionally done maj…

I'm the author of the blog post. "Tail latency has improved by YMMV for everything else" => yes, I think that's a valid (but conservative) read. Of course, in many (most?) applicat…

This is the main motivation behind learned "steering" query optimizers: even if a DBA finds the right hint for a query, it is difficult to track that hint through data changes, fut…

Just wanted to say thank you! This extension was critical to a bunch of my research (and now my lab's research as well). Being able to control fine-grained elements of each plan wh…

Ah, I missed that this requires WAL mode -- indeed, if WAL is used, one transaction should always be able to make progress.

My reading is that no deadlocks should be possible since there is only one lock (pages are "locked" optimistically, meaning that the tx is aborted if the page has changed). "Live l…

Thanks for the first-hand information! I was also curious about this. > This is not a course everyone enrolls in. This is the ticket -- at both the University of Arizona and MIT, I…

We recently published a comparison of learned indexes (including RadixSpline and the PGM index posted yesterday)in VLDB: https://vldb.org/pvldb/vol14/p1-marcus.pdf

We produced a detailed comparison of such "fitting" and "learning" techniques, available here: https://vldb.org/pvldb/vol14/p1-marcus.pdf (Thomas Neumann, one of authors of the blo…

Check out work by Jialin Ding and Vikram Nathan, they both work on multi-dimensional learned index structures. https://arxiv.org/pdf/2006.13282.pdf

https://rmarcus.info I mostly post interactive or semi-narrative explanations of technical topics I find interesting. 1-3 posts per year.

My experience is entirely different -- writing HPC code for supercomputers at Los Alamos National Lab (on and off for 5 years) made me a true Rust believer. One of the things I spe…

This would be considered absolutely batshit at all three of the R1 research universities I've been around, which spans a significant range of prestige. I think it goes to show how …

Doh! Guess I should've checked. I didn't make it to Rio last year... Figured I was gonna miss a bunch of good stuff.

I've only read part of it, but it seems great so far! I always appreciate the clarity and practicality y'all at the JGL take. I'm amazed that the implementation was under 1500 LOC!…