chore(db): renumber rows_version migration to 0240 (off staging's 0239)

Author: TheodoreSpeaks

packages/db/migrations/0240_table_rows_version.sql

@@ -0,0 +1,51 @@
+ALTER TABLE "user_table_definitions" ADD COLUMN "rows_version" bigint DEFAULT 0 NOT NULL;--> statement-breakpoint
+
+-- ============================================================
+-- Statement-level rows_version maintenance for user_table_rows.
+--
+-- rows_version is a monotonic counter keyed by the snapshot cache: a CSV stored
+-- under v{rows_version} stays valid until the table mutates. The bump MUST live
+-- in a trigger, not application code -- every row write (insert/update/delete,
+-- including order_key reorders, which are UPDATEs) must invalidate the snapshot,
+-- and a trigger is the only bypass-proof layer.
+--
+-- Mirrors the statement-level row_count triggers (migration 0224): transition
+-- tables let one UPDATE bump every affected table once per statement, so a bulk
+-- reorder or import is +1, not +N -- avoiding the per-row lock contention on the
+-- single definition row that 0224 removed. The NEW transition table carries the
+-- affected table_id for INSERT/UPDATE (table_id never changes), the OLD table for
+-- DELETE; both are aliased `changed_rows` so one function serves all three.
+-- ============================================================
+
+CREATE OR REPLACE FUNCTION bump_user_table_rows_version()
+RETURNS TRIGGER AS $$
+BEGIN
+    UPDATE user_table_definitions d
+    SET rows_version = d.rows_version + 1
+    FROM (SELECT DISTINCT table_id FROM changed_rows) c
+    WHERE d.id = c.table_id;
+
+    RETURN NULL;
+END;
+$$ LANGUAGE plpgsql;
+--> statement-breakpoint
+
+CREATE TRIGGER user_table_rows_version_insert_trigger
+    AFTER INSERT ON user_table_rows
+    REFERENCING NEW TABLE AS changed_rows
+    FOR EACH STATEMENT
+    EXECUTE FUNCTION bump_user_table_rows_version();
+--> statement-breakpoint
+
+CREATE TRIGGER user_table_rows_version_update_trigger
+    AFTER UPDATE ON user_table_rows
+    REFERENCING NEW TABLE AS changed_rows
+    FOR EACH STATEMENT
+    EXECUTE FUNCTION bump_user_table_rows_version();
+--> statement-breakpoint
+
+CREATE TRIGGER user_table_rows_version_delete_trigger
+    AFTER DELETE ON user_table_rows
+    REFERENCING OLD TABLE AS changed_rows
+    FOR EACH STATEMENT
+    EXECUTE FUNCTION bump_user_table_rows_version();