Aether/crates/aether-data/runtime/schema

Aether Schema Source

This directory is the schema maintenance workspace. Executable migrations are owned by the Postgres, MySQL, and SQLite adapters under ../../adapters/. The Postgres bootstrap snapshot is compiled from the source fragments here during aether-data builds, so there is no checked-in bootstrap artifact.

The maintenance flow is:

bash crates/aether-data/runtime/schema/compose_schema.sh generate
bash crates/aether-data/runtime/schema/compose_schema.sh compose
bash crates/aether-data/runtime/schema/compose_schema.sh check

• generate renders logical/*.toml through aether-data-schema into generated/{postgres,mysql,sqlite}. This is a build output, not another SQL source to maintain.
• compose rewrites the executable SQL from the manifest order.
• check verifies generated output is current, confirms the bootstrap source fragments still compose cleanly, and diffs each executable migration manifest against the checked-in SQL.
• split regenerates fragments from the executable SQL and is mostly for rebaselining after a deliberate bulk rewrite.

What To Edit

The schema workspace has three normal source areas:

Path	Role	Edit policy
logical/*.toml	Long-term logical table model shared by all SQL drivers.	Edit first for portable table-shape changes.
drivers/{postgres,mysql,sqlite}/	Current maintenance fragments for executable SQL.	Edit only for deployment compatibility, ordering, or generator gaps.
bootstrap/postgres/	Source fragments for the Postgres empty-database bootstrap snapshot.	Edit here when the bootstrap snapshot changes, then rebuild aether-data so build.rs regenerates the embedded snapshot.

Everything else is output:

Path	Role	Edit policy
generated/{postgres,mysql,sqlite}/	Machine-written SQL emitted from logical/*.toml for audit and drift detection.	Do not edit; regenerate with compose_schema.sh generate.
../../adapters/{postgres,mysql,sqlite}/migrations/	Runtime SQL artifacts embedded by each database adapter.	Regenerate through compose_schema.sh compose; do not edit independently.

generated/** is deliberately checked in so reviews and CI can see exactly what the logical schema compiler emits for each driver. It is not a fourth SQL source of truth, and runtime code never loads migrations from it.

overrides/ is an exception bucket, not a regular source tree. Keep it empty except for its README until a real driver-specific SQL file is needed and added to a manifest.

The generator can also be called directly:

cargo run -p aether-data-schema --bin aether-schema -- check
cargo run -p aether-data-schema --bin aether-schema -- generate
cargo run -p aether-data-schema --bin aether-schema -- print --driver postgres

Logical Schema

logical/*.toml is the long-term source for table definitions. It covers the clean baseline table set and the portable MySQL/SQLite table-creation migrations. The generator emits driver-specific SQL under generated/; those files include a directory README plus Do not edit headers and should only change through compose_schema.sh generate.

compose_schema.sh check enforces two things:

• generated SQL must match the current logical TOML source
• bootstrap source fragments must still compose cleanly for the runtime build
• required executable SQL tables must have logical definitions, so new portable tables cannot bypass the single-maintenance-source path

The migration path is incremental:

1. Add a table/domain to logical/*.toml.
2. Run compose_schema.sh generate.
3. Compare generated SQL to the current driver fragments.
4. Promote generated output into driver fragments only when that domain is intentionally ready to stop being handwritten.
5. Keep driver-specific special cases in explicit override fragments under overrides/ only when they cannot live cleanly in a driver fragment.
6. Once a domain matches, move its baseline maintenance to generated output.

The existing drivers/postgres, drivers/mysql, and drivers/sqlite fragment trees remain authoritative for executable migrations until a generated fragment is deliberately promoted.

overrides/ is reserved for rare driver-specific SQL that cannot be represented by logical schema or the normal driver fragments. Keep it small and explicit.

Targets

Target	Executable SQL	Source manifest
Postgres baseline	../../adapters/postgres/migrations/20260403000000_baseline.sql	drivers/postgres/baseline/manifest.txt
Postgres empty-database snapshot	aether-data build output (OUT_DIR/empty_database_snapshot.sql)	bootstrap/postgres/manifest.txt
MySQL baseline	../../adapters/mysql/migrations/20260403000000_baseline.sql	drivers/mysql/baseline/manifest.txt
SQLite baseline	../../adapters/sqlite/migrations/20260403000000_baseline.sql	drivers/sqlite/baseline/manifest.txt

Driver baseline source manifests are kept as a small set of numbered SQL fragments. Postgres uses execution-phase fragments so the pg_dump ordering remains byte-for-byte stable when composed:

• 001_types_and_tables.sql
• 002_defaults.sql
• 003_constraints.sql
• 004_indexes.sql
• 005_foreign_keys.sql
• 006_footer.sql
• 100_* extension files for empty-database snapshot-only additions

MySQL and SQLite use similarly numbered domain fragments (001_identity.sql through 006_usage.sql) because their baselines are shorter and already organized by domain.

The Rust migration tests compose these manifests too, so fragment drift is caught during cargo test -p aether-data split_baseline_sources_match_executable_migrations.