multiversion-concurrency-control
electric
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multiversion-concurrency-control | electric | |
---|---|---|
19 | 27 | |
67 | 4,784 | |
- | 13.0% | |
7.3 | 9.8 | |
4 months ago | 5 days ago | |
Java | Elixir | |
- | Apache License 2.0 |
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multiversion-concurrency-control
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Statelines - an idea for representing asynchronicity elegantly
The code is in this repository https://github.com/samsquire/multiversion-concurrency-control in MultiplexingThread.java and MultiplexProgramParser.java
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CRDT-richtext: Rust implementation of Peritext and Fugue
https://github.com/samsquire/multiversion-concurrency-contro...
And I implemented a 3 way text diff with myers algorithm based on https://blog.jcoglan.com/2017/02/12/the-myers-diff-algorithm...
https://github.com/samsquire/text-diff
I implemented an eventually consistent mesh protocol that uses timestamps to provide last write wins
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A collection of lock-free data structures written in standard C++11
I think I lean towards per-thread sharding instead of mutex based or lock free data structures except for lockfree ringbuffers.
You can get embarassingly parallel performance if you split your data by thread and aggregate periodically.
If you need a consistent view of your entire set of data, that is slow path with sharding.
In my experiments with multithreaded software I simulate a bank where many bankaccounts are randomly withdrawn from and deposited to. https://github.com/samsquire/multiversion-concurrency-contro...
I get 700 million requests per second due to the sharding of money over accounts.
- How to get started?
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The “Build Your Own Database” book is finished
If you want some sample code to implement MVCC, I implemented MVCC in multithreaded Java as a toy example
https://github.com/samsquire/multiversion-concurrency-contro...
First read TransactionC.java then read MVCC.java
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Let's write a setjmp
I wrote an unrolled switch statement in Java to simulate eager async/await across treads.
https://github.com/samsquire/multiversion-concurrency-contro...
The goal is that a compiler should generate this for you. This code is equivalent to the following:
task1:
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Structured Concurrency Definition
https://doc.rust-lang.org/book/ch16-00-concurrency.html
I've been working on implementing Java async/await state machine with switch statements and a scheduling loop. If the user doesn't await the async task handle, then the task's returnvalue is never handled. This is similar to the Go problem with the go statement.
https://github.com/samsquire/multiversion-concurrency-contro...
If your async call returns a handle and
- Are there any languages with transactions as a first-class concept?
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Small VMs and Coroutines
yield value2++
https://github.com/samsquire/multiversion-concurrency-contro...
I am still working on allowing multiple coroutines to be in flight in parallel at the same time. At the moment the tasks share the same background thread.
I asked this stackoverflow question regarding C++ coroutines, as I wanted to use coroutines with a thread pool.
https://stackoverflow.com/questions/74520133/how-can-i-pass-...
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Hctree is an experimental high-concurrency database back end for SQLite
This is very interesting. Thank you for submitting this and thank you for working on this.
I am highly interested in parallelism and high concurrency. I implemented multiversion concurrency control in Java.
https://github.com/samsquire/multiversion-concurrency-contro...
I am curious how to handle replication with high concurrency. I'm not sure how you detect dangerous reads+writes to the same key (tuples/fields) across different replica machines. In other words, multiple master.
I am aware Google uses truetime and some form of timestamp ordering and detection of interfering timestamps. But I'm not sure how to replicate that.
I began working on an algorithm to synchronize database records, do a sort, then a hash for each row where hash(row) = hash(previous_row.hash + row.data)
Then do a binary search on hashes matching/not matching. This is a synchronization algorithm I'm designing that requires minimal data transfer but multiple round trips.
The binary search would check the end of the data set for hash(replica_a.row[last]) == hash(replica_b.row[last]) then split the hash list in half and check the middle item, this shall tell you which row and which columns are different.
electric
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Ask HN: How Can I Make My Front End React to Database Changes in Real-Time?
I'm interested in this problem also!
I think there is a large overlap with projects that market/focus on offline-first experiences.
AFAIK this problem can be solved by:
1) Considering a client-side copy of the database that gets synced with the remote DB. This is an approach [PowerSync](https://www.powersync.com/) and [ElectricSql](https://electric-sql.com/) and [rxdb](https://rxdb.info/) take!
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Cloudflare acquires PartyKit to allow developers to build real-time multi-user
Yeah I agree with it being an exaggeration. They are certainly riding the admittedly dated perception that realtime is so hard it's only available to the Googles and Figmas. But there's now some amazing open source solutions available like Y.js and ElectricSQL[1]. The barrier has certainly come down.
[1] https://github.com/electric-sql/electric
- Ask HN: Who is hiring? (April 2024)
- FLaNK Stack 26 February 2024
- FLaNK Stack Weekly 12 February 2024
- Show HN: RemoteStorage – sync localStorage across devices and browsers
- I pwned half of America's fast food chains, simultaneously
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PostgreSQL 16 Bi-Directional Logical Replication
https://github.com/electric-sql/electric :
> ElectricSQL is a local-first software platform that makes it easy to develop high-quality, modern apps with instant reactivity, realtime multi-user collaboration and conflict-free offline support.
> Local-first is a new development paradigm where your app code talks directly to an embedded local database and data syncs in the background via active-active database replication. Because the app code talks directly to a local database, apps feel instant. Because data syncs in the background via active-active replication it naturally supports multi-user collaboration and conflict-free offline
"SQLedge: Replicate Postgres to SQLite on the Edge" (2023)
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Show HN: PowerSync – Bi-directional Postgres<>SQLite sync for offline-first apps
Yup, this is correct.
We have had some requests / discussions around adding hooks to the sync service that will support custom logic on the write path (as per https://github.com/electric-sql/electric/discussions/565). This seems like a good idea but they don't exist yet.
- Electric SQL – Local-first sync layer for web and mobile apps
What are some alternatives?
glibc - GNU Libc
fulcro - A library for development of single-page full-stack web applications in clj/cljs
tree-flat - TreeFlat is the simplest way to build & traverse a pre-order Tree in Rust
cr-sqlite - Convergent, Replicated SQLite. Multi-writer and CRDT support for SQLite
marisa-trie - MARISA: Matching Algorithm with Recursively Implemented StorAge
crdt-benchmarks - A collection of CRDT benchmarks
pybktree - Python BK-tree data structure to allow fast querying of "close" matches
wundergraph - WunderGraph is a Backend for Frontend Framework to optimize frontend, fullstack and backend developer workflows through API Composition.
abseil-cpp - Abseil Common Libraries (C++)
mycelite - Mycelite is a SQLite extension that allows you to synchronize changes from one instance of SQLite to another.
gring - Golang circular linked list with array backend
vaxine - Rich-CRDT database based on AntidoteDB.