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@iavins
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breaking databases @tursodatabase . W1 '21 @recursecenter excited about databases, storage engines and message queues
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For the past few months, I have been learning about internals of databases. I found many excellent articles on writing compilers, but I could not find many practical resources for databases. So I wrote one. CaskDB is the project I wish I had started with.
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fun fact: SQLite is the most deployed and most used database. There are over one trillion (1e12) SQLite databases in active use.
It is maintained by three people. They don't allow outside contributions.
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I always wondered how adblockers for YouTube worked, this post nicely explains it. Also, the cat-and-mouse chase between YouTube and adblockers. A fascinating read
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link to the post -
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How do they cook?
There are over 600 lines of test code for every line of code in SQLite. Tests cover 100% of branches in the library.
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Here is a fascinating story of how researchers teamed up with SQLite core developers to make it faster using Bloom filters!
Let's also dive into database internals and understand how databases implement joins.
📄Paper: SQLite - Past, Present, and Future (2022)
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This is one of the most incredible demo of distributed systems you are ever going to see, promise 🤯🤯🤯
(timestamp 53:00)
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If you want something better than Bloom filter, here are some alternatives. Found this answer which provides research progress of probabilistic data structures
Bloom filter -> Cuckoo filter -> XOR filter
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Are you an influencer? And people are bothering you with your empty Github contributions?
Look no further, use Rockstar! Rockstar generates real looking Github contribution graph so that you can focus on your business.
See how it looks on my profile:
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I highly recommend reading this excellent paper. I also had an opportunity to discuss the paper in depth with one of the authors and I learned a lot.
This week I am reading a research paper that shows a 100x reduction in tail latencies by keeping database IO asynchronous ⚡
The traditional approach, like using SQLite, leverages synchronous IO which blocks the runtime during database interactions, hurting concurrency and
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Did you know that if SQLite performs better, then the lifetime of your mobile increases?
But how?
Let's uncover that from the paper: SQL Statement Logging for Making SQLite Truly Lite. 1/n
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This is an excellent post!
@thorstenball
neatly explains why text editors don't use string rather use rope, gap buffers etc, why zed uses rope and then how they implemented rope on top of a B+Tree, called SumTree
Here it is: a new Zed Decoded post.
It's about the two data structures at the heart of Zed: the Rope & the SumTree.
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So, thats how I joined
@tursodatabase
:)
It feels surreal
Most of the career advice I see on this platform is not applicable to systems level software (OS, compilers, etc).
As I promised a cpl of weeks back, here's some tips from my career on how to develop your own career, including a real life story of how we hired
@iavins
:
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in 2021, Notion sharded their single 'monolithic' db into 32 physical dbs, each with 15 logical shards
Their post on process is excellent with a systematic approach to sharding, with schema design, capacity planning, and technical details of migration
🔗
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text phrases stolen from:
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Why?
- Most people see it from a web workload perspective. Typically, we use Client-Server databases like PostgreSQL. SQLite absolutely shines in many other cases like mobile or embedded devices.
- For a long time, SQLite did not allow concurrent writes along with readers. This
I don't get it. Why does SQLite (in production) have such a bad rep?
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I am excited to share that on September 8th, I'll be unwrapping the fascinating story of SQLite.
I am going to present the 'SQLite: Past, Present, and Future' paper at
@papersweloveblr
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It literally stands for Remote Dictionary Server.
Yes. It is a fancy hash table. A very good one.
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TIL PRQL - Pipelined Relational Query Language, pronounced “Prequel”. It compiles to SQL and claims that it makes writing complex SQL queries simple and intuitive
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Paper: How does the performance of a graph database such as Neo4j compare to the performance of a relational database such as Postgres?
"Postgres outperformed Neo4j in almost every query under various settings" oof
I found this neat article which shows how to turn Postgres into a graph database. I wonder how it fares with larger workloads. Are there any benchmarks/blogs where someone replaced Postgres with Neo4j / Dgraph, etc.?
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I sat with a friend to read this paper on SQLite, it took us only three hours. That is sufficient to get most of the ideas! 🚀
📄
details of the meetup in the next tweet 1/2
I am excited to share that on September 8th, I'll be unwrapping the fascinating story of SQLite.
I am going to present the 'SQLite: Past, Present, and Future' paper at
@papersweloveblr
1/2
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TIL about Meilisearch's badass history. A lab was building a search engine in Go and
@Kerollmops
thought it would be slow, so he created a weekend project in Rust that proved to be faster!?
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I can’t believe it’s already been a month since I joined the fantastic team at
@tursodatabase
I will be working on databases full time now. Super excited 🚀🚀
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Space shuttle style coding
PLEASE DO NOT ATTEMPT TO SIMPLIFY THIS CODE.
KEEP THE SPACE SHUTTLE FLYING.
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Thank you everyone for the amazing support. Can't believe CaskDB crossed 1000 stars already! Amazed and humbled🤗
Whats CaskDB? It's an educational project which aims to teach you writing a persistent key value store from scratch
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How do you run migrations on a large table, online?
Sometimes, the DB might end up taking a lock on full table if not done carefully.
Here is a short post which explains how not to do them in PostgreSQL and then a proper solution:
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CedarDB is based on Umbra and other related research work. The paper is a great read with a lots of new ideas
📄 Umbra: A Disk-Based System with In-Memory Performance -
CedarDB: The 🇩🇪German-powered, PostgreSQL-compatible freak-of-nature database management system based on TUM's Umbra (Thomas Neumann + team) is out of stealth and now available:
/cc
@cedar_db
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It is hard, but it is not impossible. All it takes is discipline, determination and dedication. You can do it!
I locked myself in a room, and I got this contribution graph in under two minutes using rockstar -
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found this super cool decade old video of Solomon Hyke showing docker to the public for the first time in a five minute lightning talk at a PyCon.
and then it changed everything...
📺
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SQLite approved by Ser Karpathy 🫡
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Paper: Cuckoo filters, an alternative to Bloom filters, which improve upon in three ways
1. support for deleting items dynamically
2. better lookup performance and
3. better space efficiency for applications requiring low false positive rates(ε < 3%)
📄
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@b0rk
- Designing Data-Intensive Applications by
@martinkl
- Database Internals by
@ifesdjeen
- Writing An Interpreter/Compiler In Go by
@thorstenball
- Algorithms Design Manual by
@StevenSkiena
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Weekend paper recommendation: SQLite: Past, Present, and Future
📄
I am excited to share that on September 8th, I'll be unwrapping the fascinating story of SQLite.
I am going to present the 'SQLite: Past, Present, and Future' paper at
@papersweloveblr
1/2
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Meta has published a blog post on making MySQL distributed using Raft
🔗
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Yes, they did have a Christian Code of Conduct adapted from The Rule of St. Benedict. But it was controversial and they modified it after two years, to Code of Ethics
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My patch with the fixes is now merged! This is my first contribution to the libsql core :)
C is not just a bad language. It is a demonic instrument, that leaves scars on your soul that not even time can heal.
We had a small bug recently where one extension that works with SQLite stopped working with libSQL. One of our engineers,
@iavins
, spent a whole day debugging
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wrote my first sqlite extension:
sqlite> .load ./greet
sqlite> select greet('World');
Hellooo, World!
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okay, no Soundcloud, but follow me on WhatsApp / Telegram for more database fun facts
Telegram -
WhatsApp -
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C is not just a bad language. It is a demonic instrument, that leaves scars on your soul that not even time can heal.
We had a small bug recently where one extension that works with SQLite stopped working with libSQL. One of our engineers,
@iavins
, spent a whole day debugging
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Just use a fridge. It's the best database, ever.
you should not be allowed to use a database if you can't build one from scratch
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To write a database from scratch, first, you must write a compiler from scratch.
Writing your own compiler is awesome
Writing your own database is also awesome
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TIL T-Tree
📄 A Study of Index Structures for Main Memory Database Management Systems (1986) -
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This blog post by matklad has some excellent resources on learning / programming
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TIL
@penberg
!
📄The Impact of Thread-Per-Core Architecture on Application Tail Latency -
“Thread per core” arguments conflate two stories:
- I have carefully optimized my tasks to guarantee balanced work among threads and therefore can avoid the synchronization costs of work stealing
- wahh wahh wahh sharing state in a thread safe way is hard I don’t wanna
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Are there databases which let you continue the execution of a transaction on connection failures or machine restarts?
Why don’t databases support such a feature?
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I tried to learn C earlier but couldn’t make progress. C is everywhere, from systems stuff to databases. SQLite is in C, Postgres is in C!
I am picking it up again and hoping to understand the internals. If you have any advice, do share!
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I would like to understand write-amplification in B Tree vs LSM Tree. Is there any survey/research paper explaining the same? or a blog post?
I found a few articles online, but none covered all the aspects and missed nuance. e.g. batching in LSM tree, WAL in B tree etc.
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Check this programming challenge site where you will build a TCP server -
nice.
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oof this tweet blew up. I don't have Soundcloud, but you may find my project interesting where I am trying to build a database from scratch
github -
For the past few months, I have been learning about internals of databases. I found many excellent articles on writing compilers, but I could not find many practical resources for databases. So I wrote one. CaskDB is the project I wish I had started with.
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One more alternative to Bloom filter: Split Block Bloom Filter
📄
Best part: you can read TigerBeetle’s open source implementation 👇
@iavins
If you want something that’s faster to construct than XOR / Binary Fuse Filters (e.g. if write-intensive), and simple to intuit/implement as a middle ground, plus significantly faster than Bloom Filters…
…then take a look at the Split Block Bloom Filter in Apache Impala, which
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CMU Database Talks is back with a great line up.
Excited about
@neondatabase
,
@jorandirkgreef
,
@benbjohnson
, and SplinterDB talks!
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I am trying out Fly's distributed systems coding challenge. But my code was so bad that it crashed Jepsen itself 💀
But hey, achievement unlocked I guess?
When Jepsen breaks, it also says sorry politely.
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I am never bored doing Rust. I am either busy fighting the borrow checker or reading about some new drama everyday🍿
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This is a nice page explaining how to read research papers effectively. While reading, note down and try to answer following questions and challenge your understanding
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Those are just extremes. Due to the scaling difficulties of Postgres/MySQL, people made Citus/Vitess.
Also, many NoSQL databases today are ACID compliant. They aren’t mutually exclusive, NoSQL + ACID is perfectly fine.
Run away from system design instructors who say, "Use a NoSQL database because SQL doesn't scale" 🤦♂️
It shows the sheer immaturity and lack of practical experience of the instructor because crude generalization doesn't exist in computer science and software engineering. Always
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If you are looking to contribute to open source, look no further than this
✅ Open Source Database
✅ SQLite
✅ Rust
✅ Async IO (io_uring)
Me and
@Peristocles1
have been hacking on an in-process database in Rust that aims for SQLite compatibility, but with an asynchronous architecture (but no Tokio) to support things like io_uring: DM me if you want to join the fun!
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A few days ago,
@penberg
posted about the Hekaton MVCC paper. I hit a wall implementing it.
I tried my best to figure it out and kept doubting myself because I did not know that papers could have errors!
Later, I confirmed the error with the authors:
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@largedatabank
@phil_eaton
@borjasotomayor
@justinjaffray
These are great! Some more top of my head:
- Database Internals by
@ifesdjeen
- Let's Build a Simple Database - This is classic. Though incomplete, still a great resource
- Architecture of a Database System by Stonebraker - (1/2)
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Next paper - 📄 Looking Ahead Makes Query Plans Robust
Query optimisation is an NP-Hard problem. So, people find ways to make query execution better. In this paper, the researchers introduce Lookahead Information Passing where they use Bloom Filters for faster execution 1/3
I sat with a friend to read this paper on SQLite, it took us only three hours. That is sufficient to get most of the ideas! 🚀
📄
details of the meetup in the next tweet 1/2
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@PierreZ
@therealdatabass
@ifesdjeen
@intensivedata
@martinkl
@CMUDB
@ifesdjeen
's book is just too good 💯💯💯
I would also recommend Berkeley's CS 186. It also has lecture videos (recorded in 2018). The assignments are open, unlike CMU's course. Also, the assignment uses Java, more approachable than C++, imo.
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I enjoyed reading this post by Philip O’Toole, which goes through the journey, design and implementation of rqlite (which came out nine years ago!)
It details consensus algorithm upgrades, scaling read performance, reducing disk usage etc.
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