ALTER TABLE "files" ADD COLUMN "size" integer DEFAULT 0 NOT NULL;--> statement-breakpoint
ALTER TABLE "messages" ADD COLUMN "active_child_id" text;--> statement-breakpoint
UPDATE "messages" m
SET "active_child_id" = (
    SELECT child."id"
    FROM "messages" child
    WHERE child."parent_message_id" = m."id"
    ORDER BY child."created_at" ASC
    OFFSET (m."focused_index" - 1)
    LIMIT 1
)
WHERE m."focused_index" IS NOT NULL AND m."focused_index" > 0;--> statement-breakpoint
ALTER TABLE "messages" DROP COLUMN "focused_index";