openehr-sqlite

openEHR persistence for SQLite 3 — a complete embedded store.

Conformance level: Store#

Unlike the four dialect-only crates, this one contains a working SqliteStore and runs the shared conformance suite against a real database in its own tests: every commit rule, every read, the archetype index, the append-only triggers, and DDL idempotence.

SQLite is the only one of the five engines that can be verified without provisioning a server, so it is the one where the shared logic actually gets exercised. See openehr-store/spec/conformance.md.

use openehr_sqlite::SqliteStore;
use openehr_store::{Store, conformance};

let mut store = SqliteStore::in_memory()?;
store.install()?;

let ehr = conformance::sample_ehr();
store.create_ehr(&ehr)?;
store.create_contribution(ehr.ehr_id(), &conformance::sample_contribution(uid, &[1]))?;
store.commit_composition(ehr.ehr_id(), &version, uid)?;

// The record as it stood at a moment in time.
let then = store.version_at_time(&container, &at)?;

What it guarantees#

The same commit rules as the library. A version belonging to another container, a duplicate, a missing predecessor, or a stale one are each refused and each distinguishable. The stale case is the one that matters: two clients both read version 2 and both write version 3, and openEHR's answer is a branch rather than a silent overwrite — so the store refuses and lets the caller decide.

Append-only, in the database. UPDATE and DELETE on the version table are refused by triggers, not by application convention. A guarantee that lives only in Rust ends the first time somebody opens the file with the sqlite3 CLI, and a test goes around the store to prove it.

Validation before writing. An invalid composition is refused before the transaction opens, so a refused commit leaves no container behind. A store that accepted one would make every later reader's validate() fail on data it cannot fix.

Foreign keys actually on. SQLite disables them per connection by default; this store enables them explicitly. Not doing so would accept a version pointing at a container that does not exist, silently, while the schema said otherwise.

SQLite specifics#

Decision	Why
`TEXT` for identifiers, with no lengths	SQLite applies type affinity rather than enforcement, so a declared length would be documentation nothing checks.
`TEXT` for JSON	There is no JSON type; the JSON1 extension operates on `TEXT`, so this is both the honest declaration and the working one.
`INTEGER` — Unix seconds — for derived instants	SQLite has no date type. Storing the derived instant as text would make it sort identically to the authoritative column, collapsing the distinction the two columns exist to keep.
`bundled` SQLite	The DDL and the JSON1 functions are version-dependent, so the engine is pinned rather than whatever the host ships.

Every instant is stored twice#

openEHR times are ISO 8601 strings with deliberate partial precision: 2024-05 is a date known to the month and is not 2024-05-01. A native timestamp column silently completes it — fabricating a clinical fact — and normalises the lexical form.

So each time occupies …_text (authoritative, exact) and …_utc (derived, nullable, for ordering). The derived column is NULL whenever the instant is not established, and version_at_time skips those rows rather than guessing at a time zone — exactly as the library does.

Testing#

cargo test

Runs the shared suite against an in-memory database, plus this crate's own tests for the trigger, the validation gate, lexical fidelity, and DDL idempotence — and tests/dialects.rs, which compares all five engines' DDL and fails if any two agree.

Licence#

MIT OR Apache-2.0.