hyperledger-labs / fabric-smart-client / 41292780493

92%

Build Type

push

github

Committed by web-flow

Commit Message

feat(storage): add versioned schema migrations (#2416)

The new package platform/view/services/storage/driver/sql/common/migrate records a schema version per SQL store and runs ordered schema steps. A store opts in by implementing migrate.Versioned (StoreName and Steps). Each table prefix gets one <prefix>_schema_versions table with a row per store holding version and readable_by. No FSC store implements Versioned yet, so nothing changes at runtime.

A step holds SQL statements and an optional Go function, which runs after the SQL in the same transaction, for changes SQL cannot express such as a backfill computed in Go. The function runs statements through migrate.Execer, the ExecContext/QueryContext/QueryRowContext subset shared by *sql.Tx, *sql.Conn and *sql.DB. It does not receive a *sql.Tx because SQLite steps run in BEGIN IMMEDIATE on a raw connection, and the modernc driver sets the begin mode only per pool.

Migrate reads the store's row without taking the migration lock and returns if nothing is pending. A readable_by above the binary's latest step returns ErrSchemaTooNew, a corrupt row returns an error, and WithCheckOnly returns ErrPending instead of running steps. When steps are pending:
- Postgres migrators of one prefix exclude each other with a session advisory lock on a dedicated connection. The waiter polls pg_try_advisory_lock, logs every 10s and has no timeout, so lock_timeout does not apply.
- SQLite runs each step in BEGIN IMMEDIATE on the write connection; across processes the wait is bounded by busy_timeout.
Each step runs in its own transaction, re-reads the row, skips a step another migrator applied meanwhile, and records the new version. A failed step rolls back, SQL and Go function together, and names the store and the step. A different Go type claiming the same store row in the same database is rejected.

The six driver constructors (sqlite, postgres and memory, for view and fabric stores) call migrate.CreateSchema, which run... (continued)

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