CREATE TABLE `relay_migrations` (
	`id` text PRIMARY KEY NOT NULL,
	`tenant_id` text NOT NULL,
	`source_node_id` text NOT NULL,
	`target_node_id` text NOT NULL,
	`source_generation` integer NOT NULL,
	`target_generation` integer NOT NULL,
	`state` text DEFAULT 'quiescing' NOT NULL,
	`backup_ref` text,
	`manifest_sha256` text,
	`requested_by` text NOT NULL,
	`reason` text NOT NULL,
	`started_at` text NOT NULL,
	`updated_at` text NOT NULL,
	`switched_at` text,
	`completed_at` text,
	`last_error_code` text,
	FOREIGN KEY (`tenant_id`) REFERENCES `tenant_instances`(`id`) ON UPDATE no action ON DELETE no action,
	FOREIGN KEY (`source_node_id`) REFERENCES `relay_nodes`(`id`) ON UPDATE no action ON DELETE no action,
	FOREIGN KEY (`target_node_id`) REFERENCES `relay_nodes`(`id`) ON UPDATE no action ON DELETE no action,
	CHECK (`target_generation` = `source_generation` + 1),
	CHECK (`source_node_id` <> `target_node_id`),
	CHECK (`state` IN ('quiescing', 'copying', 'switching', 'draining', 'completed', 'failed'))
);
--> statement-breakpoint
CREATE UNIQUE INDEX `idx_relay_migrations_one_active`
ON `relay_migrations` (`tenant_id`)
WHERE `state` IN ('quiescing', 'copying', 'switching', 'draining');
--> statement-breakpoint
CREATE INDEX `idx_relay_migrations_source_state`
ON `relay_migrations` (`source_node_id`, `state`, `updated_at`);
--> statement-breakpoint
CREATE INDEX `idx_relay_migrations_target_state`
ON `relay_migrations` (`target_node_id`, `state`, `updated_at`);