Justin
@justinjaffray
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turning to the succor of modern computing machines, let us renounce all analytic tools
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A friend at LinkedIn who would prefer to remain nameless tells me they reduced their storage costs by 7% just by manually interning the phrases "Congratulations!", and "Congrats, <name>!" in their comment database schema.
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for my money the best paper ever written on query optimization is this one from 1998
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I came across a really cute algorithm for count-distinct yesterday and couldn't believe I hadn't seen it before, so I did a little write-up on how it works:
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This week I picked a couple query optimizations arbitrarily and checked if DuckDB, CockroachDB, Postgres, and Sqlite did them or not:
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*first contact with an alien*
me: hey btw can you guys do SAT in polynomial time
<alien jeff👽 has sent >
me: is this c++?
them: yeah just run make
me: it says im missing something called "libyorbo"
them: oh really? thats required for posix here
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today is the actual anniversary of the first NULL BITMAP, and so I wanted to share a couple of my favourite issues from the first year, in no order
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wrote a post on some broad strokes differences between push vs. pull query engines
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My tweet about Chaudhuri's 1998 paper was weirdly popular so here is a small sampling of some other query planning related papers that I really like
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hello...today marks the 52nd weekly NULL BITMAP. to celebrate i reviewed some books from my bookshelf. thank you for your patronage
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NULL BITMAP: I wrote down some thoughts on the problems you run into when trying to represent non-treelike expressions for query languages, and some of the solutions I've seen:
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it requires such an enormous brain to market your database saas like its an iphone. in awe
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@TylerGlaiel
born too early to use the app store. born too late to fall for email scams. born just in time to know how to use a filesystem
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wrote a post about compaction, from the perspective of comparing the behaviour of CockroachDB's Pebble with that of Differential Dataflow:
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Why Are Query Plans Trees?
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Today is my first day at
@MaterializeInc
!
I also have a new blog post—in preparation for starting, I read some of the papers for the tech underlying the system, which led me to an interesting problem which I wrote about here:
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been a while since a good ol' fashioned celeste gif: you can get the berry on 1400m without ever dashing cc
@baldjared_
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my take these days is that nobody actually cares about database correctness ~at all. 98% of people who say they like jepsen actually just like snark
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The Case of a Curious SQL Query
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This week I wrote a bit about some of the ways I have seen columns represented in query optimizers, in particular a nonobvious (IMO) way that is vastly superior (IMO) to the obvious way:
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ceci n'est pas une jpeg
there is an incredible slapfight happening over on Wikipedia over whether or not to classify NFTs as art
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NULL BITMAP: a very brief intro to some fundamentals of join ordering:
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this week i wrote about a reductive but helpful (to me) way of thinking about how datalog works. and also followed up on some threads from last week. i hope you like it
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I really enjoyed
@TylerGlaiel
's post the other day, and while it wasn't the point, I thought his pathfinding problem was interesting enough that I should write down some thoughts on it:
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what the heck is a 'redo log.' what the heck is a 'memtable.' all this and more in my latest post
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NULL BITMAP: I wrote about some of the purposes, and challenges I've experienced, with designing flexible IRs
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I wrote about (exactly) what can go wrong with Snapshot Isolation: What Does Write Skew Look Like?
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new post: query optimizer cost models are notoriously complex, what does this mean and how can we alleviate it?
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NULL BITMAP: some musing over a general guideline when query planning
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Unfortunately, this same unnamed friend has just gotten fired for unsportsmanlike conduct during a company water polo game. As a result I can no longer verify the validity of these claims
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me: can you just explain the algorithm
them (getting flustered): oh uh well i haven't done this since college man.
<alien jeff👽 has sent >
me: this is getting an index out of bounds when i run it
them: im not used to doing this without my IDE
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just had a very productive call with dijkstra. goto is back on the table
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hello... the first issue of my newsletter NULL BITMAP is out and we are starting off with a classic but surprising issue that comes up with implementing SQL: the halloween problem. you can read it and give me your email (🔫) here
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fixing a typo in the readme of a github repo with 35 stars and then putting
Coder | Dreamer | Open Source Evangelist
Location: ✈️ -> The World
in my twitter bio
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On NULL BITMAP: I wrote a little bit about why you might want multiple returns in SQL, and what that might look like
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i used to work at a company where the IT staff would regularly send out fake phishing emails and you'd get a talking to if you clicked on one. this was my favourite one they ever sent
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NULL BITMAP: I wrote up a little demonstration of the way that the naive way of constructing a database benchmark can be misleading
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Hello! It is time for another “here’s a way to think about how an LSM works” NULL BITMAP:
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I saw
@irfansharifm
at a Go meetup in Toronto today. I told him how cool it was to meet him in person, but I didn’t want to bother him and ask him for photos or anything.
He said, “Oh, like you’re doing now?” and went back to making his slides.
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DB VENDORS: you still have to handle aborts and issue retries at lower isolation levels, right? so it shouldnt matter if theyre more frequent at serializable
DEVELOPERS: well the way we handle retries is to display an error and tell the user “something went wrong”
Fascinating disconnect I’ve seen on this one:
- academic researchers: SERIALIZABLE isn’t the default? But everyone enables it first thing, right?
- database users: SERIALIZABLE exists?
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This week I wrote some quick thoughts about sorts of problems that resist abstraction because they don't compose:
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today on NULL BITMAP...we are unraveling an international database benchmarking conspiracy
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engineers: you know, declarative languages. like sql.
mathematicians:
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happy to share that i will be joining
@MaterializeInc
starting in april! super excited to work with this team!
Big news! Like, REALLY big news.
We're popping the lid on
@MaterializeInc
today. You can check out our sweet new web page: , and click through to the first in a series of blog posts:
There will be more in the coming days, but ...
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HELLO!!! for the month of february i decided i was going to make a ZINE. so I made a strategy guide for a game that doesn't exist. i hope you enjoy FISHERGIRL
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important annoucement: i have written a program that solves the halting problem. annoyingly, my little brother Bungo unplugged my mac so i am currently powering it back on. luckily i ran fsync on the source file before i lost power
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hey ✌️ this is my last week at cockroach labs. excited for something new, but sad to be leaving. it's been a true privilege to work with some of the smartest, most thoughtful people i've known
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i hope you're all happy with yourselves. my good friend jia tan has been inconsolable
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got 15th at the sacred torch premodern tournament w this 👍 great event
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it's monday!!! time for NULL BITMAP issue
#5
: some thoughts on Unity and also some thoughts about a couple more papers I liked from VLDB:
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I wrote up some thoughts about the process of generating SQL queries for testing. It includes a plea for ideas on how to unify semantic analysis and query generation!
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it’s too bad query languages don’t really seem to capture people’s imagination like programming languages do. it would be cool to have a lot more random crappy half baked hobby query languages floating around (sincere)
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i was very excited to join my friends
@conor_power23
and
@lisabdunlap
to talk about writing and databases and writing about databases! we had a great chat
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are there any languages that have type-level debuggers? like if you have some nontrivial trait/template level stuff, some way to step through unification?
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guy emails me to say he likes my blog, offers a chat with an eng about their product. im not looking right now but i hop on the call anyway to see whats up. its with a recruiter instead. they ask why they dont have my resume, i say because i never applied. 2 weeks later:
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leetcode/interview prep culture is like the most joyless possible interpretation of programming. it makes me very sad
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*guy who has had two decades of in-office work to make industry connections and friendships voice* yeah i dont see why we should ever go back into the office, really. remote is the future
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lol i deleted this tweet because it started getting random likes which weirded me out and i just found out it was because it was in a guardian article
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if i were a query optimizer i would simply accurately compute the size of each intermediate result set
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db correctness bugs: 0.001% of my data validity errors
hardware problems: 0.01% of my data validity errors
application logic: 99% of my data validity errors
someone who is good at applications please help me budget this my software is dying
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Data Stuff is a new weekly newsletter about databases by
@narayanarjun
and me (and is not affiliated with any similarly named newsletters)
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hello, one more life update, as of this month i am a "research software engineer" working with some cool people at Sutter Hill. please update your spreadsheets
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i've been informed that i am once again on god's favourite website
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this man is unstoppable
We introduce Ternary Logic Partitioning (TLP), a general, effective approach for finding logic bugs in DBMS. It nicely complements our work on PQS and NoREC. TLP already found 175 bugs in widely-used DBMS, and can detect bugs in a wide range of features.
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Finished my
#pico8
#LD33
game:
http://t.co/MUCCuQ3pxi
awesome speedy snail action
http://t.co/CBwZiJhOnH
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Using overly technical language in communication can be alienating. Here are some jargon terms nerds love to use that I think are problematic:
"Computer" instead of "thingy"
"Program" instead of "thingy"
"Project" instead of "thingy"
"Office" instead of "thingy"
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NULL BITMAP: Another non-databases topic, a strategy for playing a game that I think wasn't actually intended to be played
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CODD DEFINED "RELATIONALLY COMPLETE" TO MEAN "EQUIVALENT TO RELATIONAL CALCULUS" DESPITE NOT EVEN HAVING A NOTION OF RECURSION, IF YOU ASK ME, DATALOG IS A MUCH MORE NATURAL STARTING POINT,
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if they had put FROM before SELECT in the sql grammar it would be a whole different ballgame out there i tell you what
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