stuarthalloway

7 ms·

1.
by stuarthalloway 2y ago
Thanks Kyle! It is evident that our docs were insufficient. Rich and I have written what we hope is clearer, more comprehensive documentation about Datomic’s transaction model. We hope that this can preempt common misconceptions and we welc
2.
by stuarthalloway 2y ago
When we designed Datomic (circa 2010), we were concerned that many languages had better support for lists than for sets, in particular list literals and no set literals. Clojure of course had set literals from the beginning...
3.
by stuarthalloway 2y ago
Formal verification is very powerful but still not full assurance. Fun fact: Testing and monitoring of Datomic has sometimes uncovered design flaws in underlying storages that formal verification missed.
4.
by stuarthalloway 2y ago
It is worth noting here that Datomic's intra-transaction semantics are not a decision made in isolation, they emerge naturally from the information model. Everything in a Datomic transaction happens atomically at a single point in time
5.
by stuarthalloway 2y ago
Ed Wible is a founder of Nubank and chose Datomic. He and Lucas Cavalcanti gave a talk on it at Clojure/conj 2014. https://www.youtube.com/watch?v=7lm3K8zVOdY
6.
by stuarthalloway 2y ago
What does the following expression return? (let [x 1] [(inc x) (inc x)]) In Clojure the answer is [2 2]. A beginner might guess [2 2] or [2 3]. Both are reasonable guesses, so a beginner needs to be quite careful! But that isn't partic
7.
by stuarthalloway 2y ago
Datomic software needed no changes as a result of Jepsen testing. All functionality in datomic.api is unchanged.
8.
by stuarthalloway 2y ago
Mea culpa on the docs, mea culpa. Better now [1]. In order for user code to impose invariants over the entire transaction, it must have access to the entire transaction. Entity predicates have such access (they are passed the after db, whic
9.
by stuarthalloway 2y ago
As a proponent of just such tools I would say also that "enough rope to shoot(?) yourself" is inherent in tools powerful enough to get anything done, and is not a tradeoff encountered only when reaching for high power or low cerem
10.
by stuarthalloway 2y ago
As Jepsen confirmed, Datomic’s mechanisms for enforcing invariants work as designed. What does this mean practically for users? Consider the following transactional pseudo-data: [ [Stu favorite-number 41] ;; maybe more stuff [Stu favorite-n
11.
by stuarthalloway 5y ago
Do you have a specific example? Datomic is great for evolving in prod ( https://blog.datomic.com/2017/01/the-ten-rules-of-schema-gro... ), and Clojure is a great language for generating data (or ETL) when you want t
12.
by stuarthalloway 6y ago
All Datomic consulting will continue.
13.
by stuarthalloway 6y ago
And Fressian https://github.com/Datomic/fressian/wiki
14.
by stuarthalloway 8y ago
That depends on what queries the peer runs. In both On-Prem and Cloud, Datomic maintains an in-memory LRU object cache. Also, you can send queries with different working sets to different processes without having to shard data on ingest. Fo
15.
by stuarthalloway 8y ago
Hm, I should have said "value proposition", e.g. SSDs are low latency but can fail, S3 is high latency but "never" fails, etc. Datomic is designed for data sets larger than memory, and also to do a good job caching worki
16.
by stuarthalloway 8y ago
Datomic keeps your database in the same memory space as your application code, backed by SSD, backed by EFS, backed by S3/DynamoDB. Each layer of this cache provides a different value, and the whole cache system is automatic and eterna
17.
by stuarthalloway 9y ago
You don't have to be very far "in" AWS to try Cloud. The bastion server will let you connect from anywhere, so the idea is that the only infrastructure you need is a laptop and an internet connection. That said, we understand
18.
by stuarthalloway 9y ago
Cloud uses clients, not peers, so those apps can be much more lightweight. I have tested down to 128M per Clojure (JVM) client, which is an order of magnitude less mem than a typical peer.
19.
by stuarthalloway 9y ago
Datomic Cloud makes it much easier to get started on AWS. It takes only a few minutes to sign up, see https://www.datomic.com/videos.html for a walkthrough.
20.
by stuarthalloway 9y ago
Cloud is definitely the preferred way to get started if you are on AWS. When running the On-Prem version you also have to manage (and pay for) storage. Cloud also puts less load on DynamoDB, which can dominate your spend.
21.
by stuarthalloway 9y ago
That should fit easily in the Solo Topology at about $1/day.
22.
by stuarthalloway 10y ago
Alex Miller is the person primarily responsible for triaging Clojure tickets. For a thoughtful, balanced assessment of the issues Ashton raises, read Alex's detailed comment on the original post: http://ashtonkemerling.com&#
23.
by stuarthalloway 10y ago
Hi, I am a Clojure committer and I just closed http://dev.clojure.org/jira/browse/CLJ-1013 . Even though this issue is not a bug, explaining why is not entirely trivial. I have already spent 15 minutes on it, and h
24.
by stuarthalloway 10y ago
Or like leaving the house without a suit of plate mail.
25.
by stuarthalloway 13y ago
We (Cognitect) appreciate the power of negation, and it has always been part of the plan. From a priority perspective, negation doesn't open categoric new possibilities for our customers in the way that excision, or the log API, or a
26.
by stuarthalloway 13y ago
"The only way to have such a versioned history is ..." is incorrect, and trivially so. Datomic provides one existence proof of this: Datomic's history data is kept in distinct data structures, so it is "pay as you go&quo
27.
by stuarthalloway 13y ago
http://docs.datomic.com/acid.html
28.
by stuarthalloway 14y ago
Just downloading it will give you blisters.
29.
by stuarthalloway 14y ago
Additional analyzers can be added. The vision is definitely not language-specific, and Rich has already done some design work for a Java analyzer.
30.
by stuarthalloway 14y ago
It is important to understand that datalog is not a new query language. It is an old one, with a strong pedigree. It has power equivalent to the relational model plus recursion. SPARQL is cool, and they did a good job making it look a littl

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