58 lines
3.4 KiB
Markdown
58 lines
3.4 KiB
Markdown
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# Datomish
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Datomish is a persistent, embedded knowledge base. It's written in ClojureScript, and draws heavily on [DataScript](https://github.com/tonsky/datascript) and [Datomic](http://datomic.com).
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Note that at time of writing, there's nothing here.
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## Motivation
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Datomish is intended to be a flexible relational (not key-value, not document-oriented) store that doesn't leak its storage schema to users, and doesn't make it hard to grow its domain schema and run arbitrary queries.
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Our short-term goal is to build a system that, as the basis for a User Agent Service, can support multiple [Tofino](https://github.com/mozilla/tofino) UX experiments without having a storage engineer do significant data migration, schema work, or revving of special-purpose endpoints.
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## Comparison to DataScript
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DataScript asks the question: "What if creating a database would be as cheap as creating a Hashmap?"
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Datomish is not interested in that. Instead, it's strongly interested in persistence and performance, with very little interest in immutable databases/databases as values or throwaway use.
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One might say that Datomish's question is: "What if an SQLite database could store arbitrary relations, for arbitrary consumers, without them having to coordinate an up-front storage-level schema?"
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(Note that [domain-level schemas are very valuable](http://martinfowler.com/articles/schemaless/).)
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Another possible question would be: "What if we could bake some of the concepts of CQRS and event sourcing into a persistent relational store, such that the transaction log itself were of value to queries?"
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Some thought has been given to how databases as values — long-term references to a snapshot of the store at an instant in time — could work in this model. It's not impossible; it simply has different performance characteristics.
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Just like DataScript, Datomish speaks Datalog for querying and takes additions and retractions as input to a transaction. Unlike DataScript, Datomish's API is asynchronous.
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Unlike DataScript, Datomish exposes free-text indexing, thanks to SQLite.
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## Comparison to Datomic
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Datomic is a server-side, enterprise-grade data storage system. Datomic has a beautiful conceptual model. It's intended to be backed by a storage cluster, in which it keeps index chunks forever. Index chunks are replicated to peers, allowing it to run queries at the edges. Writes are serialized through a transactor.
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Many of these design decisions are inapplicable to deployed desktop software; indeed, the use of multiple JVM processes makes Datomic's use in a small desktop app, or a mobile device, prohibitive.
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Datomish is designed for embedding, initially in an Electron app ([Tofino](https://github.com/mozilla/tofino)). It is less concerned with exposing consistent database states outside transaction boundaries, because that's less important here, and dropping some of these requirements allows us to leverage SQLite itself.
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## Contributing
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Please note that this project is released with a Contributor Code of Conduct.
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By participating in this project you agree to abide by its terms.
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See [CONTRIBUTING.md](/CONTRIBUTING.md) for further notes.
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This project is very new, so we'll probably revise these guidelines. Please
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comment on a bug before putting significant effort in if you'd like to
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contribute.
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## License
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At present this code is licensed under MPLv2.0. That license is subject to change prior to external contributions.
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