Reference

DatabaseMigrator

Package Trax.Effect.Data.Postgres·Namespace Trax.Effect.Data.Postgres.Utils·Source DatabaseMigrator.cs

Applies the Postgres migration scripts embedded in Trax.Effect.Data.Postgres, journaled by DbUp in trax.migrations. UsePostgres calls Migrate during service registration unless SkipMigrations was called. The SQLite provider has its own, described on UseSqlite.

Signature

namespace Trax.Effect.Data.Postgres.Utils;
 
public static class DatabaseMigrator
{
    public static Task Migrate(string connectionString);
    public static UpgradeEngine CreateEngineWithEmbeddedScripts(string connectionString);
}

Members

Behavior

• Migrate takes a session advisory lock (a two-key lock, apart from the single-key space the scheduler's leader lock uses) and holds it until every script has run, so hosts starting together migrate one after another. The wait has no timeout.
• Inside the lock it creates the trax schema, drops any INVALID index a script builds that an interrupted CREATE INDEX CONCURRENTLY left behind, and applies the pending scripts. An invalid index no script builds is left alone.
• Scripts run without a transaction, one statement at a time. A script that stops partway keeps the statements before the failure and is not journaled, so it runs again from the top at the next start. Every script from 046 on can be run again.
• Scripts run with a lock_timeout of five seconds. When a script gives up on a lock (55P03), or a unique index a script builds meets a duplicate (23505 naming that index), the pending scripts run again, up to ten times, and then the error is thrown.
• Every connection it opens is unpooled and has its time zone pinned to UTC.

Example

using Trax.Effect.Data.Postgres.Utils;
 
await DatabaseMigrator.Migrate(connectionString);

See also

• Run migrations outside startup
• Database migrations, what each migration changes
• Writing Migrations