feat: add migration_table name option

[kriswuollett]

Add migration_table option to enable sharing a database among multiple apps/clients. It is the responsibility of the user to ensure database permissions for the database role performing the migration is not able affect other co-hosted apps/clients done in separate migration "partitions".

• fixes [CLI] How to set schema for _sqlx_migrations table? #1835, fixes sqlx::migrate!() single DB multiple application support #1698, fixes Migrations with namespaces #1356, fixes Migration table renaming #946

[kriswuollett]

Tested locally with sqlite by cargo install the cli with --git flag for this branch.

[kriswuollett]

Does this seem like a reasonable approach to quickly satisfy the needs outlined in the use cases before I do more things like add tests?

If more migration options, or some more refactoring is needed later, it may be warranted to look at refactoring the relationship between the migration and the database connection. They seem too tightly bound when the database connection is required to know about the migration table, _sqlx_migrations, when it may be more reasonable to just have a function to ask if a table exists, select from it, etc. -- currently the migration table name is hard-coded in every database connection implementation, e.g., postgres:

sqlx/sqlx-postgres/src/migrate.rs

Lines 90 to 111 in d0fbe7f

	impl Migrate for PgConnection {
	fn ensure_migrations_table(&mut self) -> BoxFuture<'_, Result<(), MigrateError>> {
	Box::pin(async move {
	// language=SQL
	self.execute(
	r#"
	CREATE TABLE IF NOT EXISTS _sqlx_migrations (
	version BIGINT PRIMARY KEY,
	description TEXT NOT NULL,
	installed_on TIMESTAMPTZ NOT NULL DEFAULT now(),
	success BOOLEAN NOT NULL,
	checksum BYTEA NOT NULL,
	execution_time BIGINT NOT NULL
	);
	"#,
	)
	.await?;
	Ok(())
	})
	}

[IgnisDa]

Hey @kriswuollett any updates on this? I would like to see this merged too.

[kriswuollett]

@abonander, are you willing to work with an externally contributed PR to implement a migration table name option? I assume I'd need to add in schema/table name validation for the new option. Is there some other approach that would be preferred to the rather direct way I implemented the PR?

[bilemon]

+1 @abonander is there any interest on getting @kriswuollett's change reviewed and merged, or potentially helping define what you'd prefer to see? Or is this a non-priority at the moment for launchbadge (which is fine too)?