Better migration handling

scnserver/db/schema/primary_migration_5_6.sql

@@ -0,0 +1,49 @@
+
+DROP INDEX "idx_deliveries_receiver";
+
+CREATE TABLE deliveries_new
+(
+    delivery_id         TEXT                                                     NOT NULL,
+
+    message_id          TEXT                                                     NOT NULL,
+    receiver_user_id    TEXT                                                     NOT NULL,
+    receiver_client_id  TEXT                                                     NOT NULL,
+
+    timestamp_created   INTEGER                                                  NOT NULL,
+    timestamp_finalized INTEGER                                                      NULL,
+
+
+    status              TEXT     CHECK(status IN ('RETRY','SUCCESS','FAILED'))   NOT NULL,
+    retry_count         INTEGER                                                  NOT NULL   DEFAULT 0,
+    next_delivery       INTEGER                                                      NULL   DEFAULT NULL,
+
+    fcm_message_id      TEXT                                                         NULL,
+
+    PRIMARY KEY (delivery_id)
+) STRICT;
+
+UPDATE deliveries SET next_delivery  = NULL;
+
+INSERT INTO deliveries_new
+SELECT
+    delivery_id,
+    message_id,
+    receiver_user_id,
+    receiver_client_id,
+    timestamp_created,
+    timestamp_finalized,
+    status,
+    retry_count,
+    next_delivery,
+    fcm_message_id
+FROM deliveries;
+
+
+DROP TABLE deliveries;
+ALTER TABLE deliveries_new RENAME TO deliveries;
+
+
+CREATE INDEX "idx_deliveries_receiver" ON deliveries (message_id, receiver_client_id);
+
+
+