feat: add notification deduplication trigger (#14172)

coderd/database/dump.sql

@@ -223,6 +223,24 @@ CREATE TYPE workspace_transition AS ENUM (
     'delete'
 );
 
+CREATE FUNCTION compute_notification_message_dedupe_hash() RETURNS trigger
+    LANGUAGE plpgsql
+    AS $$
+BEGIN
+    NEW.dedupe_hash := MD5(CONCAT_WS(':',
+                                     NEW.notification_template_id,
+                                     NEW.user_id,
+                                     NEW.method,
+                                     NEW.payload::text,
+                                     ARRAY_TO_STRING(NEW.targets, ','),
+                                     DATE_TRUNC('day', NEW.created_at AT TIME ZONE 'UTC')::text
+                           ));
+    RETURN NEW;
+END;
+$$;
+
+COMMENT ON FUNCTION compute_notification_message_dedupe_hash() IS 'Computes a unique hash which will be used to prevent duplicate messages from being enqueued on the same day';
+
 CREATE FUNCTION delete_deleted_oauth2_provider_app_token_api_key() RETURNS trigger
     LANGUAGE plpgsql
     AS $$
@@ -678,9 +696,12 @@ CREATE TABLE notification_messages (
     updated_at timestamp with time zone,
     leased_until timestamp with time zone,
     next_retry_after timestamp with time zone,
-    queued_seconds double precision
+    queued_seconds double precision,
+    dedupe_hash text
 );
 
+COMMENT ON COLUMN notification_messages.dedupe_hash IS 'Auto-generated by insert/update trigger, used to prevent duplicate notifications from being enqueued on the same day';
+
 CREATE TABLE notification_preferences (
     user_id uuid NOT NULL,
     notification_template_id uuid NOT NULL,
@@ -1846,6 +1867,8 @@ CREATE UNIQUE INDEX idx_users_email ON users USING btree (email) WHERE (deleted
 
 CREATE UNIQUE INDEX idx_users_username ON users USING btree (username) WHERE (deleted = false);
 
+CREATE UNIQUE INDEX notification_messages_dedupe_hash_idx ON notification_messages USING btree (dedupe_hash);
+
 CREATE UNIQUE INDEX organizations_single_default_org ON organizations USING btree (is_default) WHERE (is_default = true);
 
 CREATE INDEX provisioner_job_logs_id_job_id_idx ON provisioner_job_logs USING btree (job_id, id);
@@ -1918,6 +1941,8 @@ CREATE TRIGGER trigger_update_users AFTER INSERT OR UPDATE ON users FOR EACH ROW
 
 CREATE TRIGGER trigger_upsert_user_links BEFORE INSERT OR UPDATE ON user_links FOR EACH ROW EXECUTE FUNCTION insert_user_links_fail_if_user_deleted();
 
+CREATE TRIGGER update_notification_message_dedupe_hash BEFORE INSERT OR UPDATE ON notification_messages FOR EACH ROW EXECUTE FUNCTION compute_notification_message_dedupe_hash();
+
 ALTER TABLE ONLY api_keys
     ADD CONSTRAINT api_keys_user_id_uuid_fkey FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;
 

coderd/database/migrations/000245_notifications_dedupe.down.sql

@@ -0,0 +1,4 @@
+DROP TRIGGER IF EXISTS update_notification_message_dedupe_hash ON notification_messages;
+DROP FUNCTION IF EXISTS compute_notification_message_dedupe_hash();
+ALTER TABLE IF EXISTS notification_messages
+    DROP COLUMN IF EXISTS dedupe_hash;

coderd/database/migrations/000245_notifications_dedupe.up.sql

@@ -0,0 +1,33 @@
+-- Add a column to store the hash.
+ALTER TABLE IF EXISTS notification_messages
+    ADD COLUMN IF NOT EXISTS dedupe_hash TEXT NULL;
+
+COMMENT ON COLUMN notification_messages.dedupe_hash IS 'Auto-generated by insert/update trigger, used to prevent duplicate notifications from being enqueued on the same day';
+
+-- Ensure that multiple notifications with identical hashes cannot be inserted into the table.
+CREATE UNIQUE INDEX ON notification_messages (dedupe_hash);
+
+-- Computes a hash from all unique messages fields and the current day; this will help prevent duplicate messages from being sent within the same day.
+-- It is possible that a message could be sent at 23:59:59 and again at 00:00:00, but this should be good enough for now.
+-- This could have been a unique index, but we cannot immutably create an index on a timestamp with a timezone.
+CREATE OR REPLACE FUNCTION compute_notification_message_dedupe_hash() RETURNS TRIGGER AS
+$$
+BEGIN
+    NEW.dedupe_hash := MD5(CONCAT_WS(':',
+                                     NEW.notification_template_id,
+                                     NEW.user_id,
+                                     NEW.method,
+                                     NEW.payload::text,
+                                     ARRAY_TO_STRING(NEW.targets, ','),
+                                     DATE_TRUNC('day', NEW.created_at AT TIME ZONE 'UTC')::text
+                           ));
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+COMMENT ON FUNCTION compute_notification_message_dedupe_hash IS 'Computes a unique hash which will be used to prevent duplicate messages from being enqueued on the same day';
+CREATE TRIGGER update_notification_message_dedupe_hash
+    BEFORE INSERT OR UPDATE
+    ON notification_messages
+    FOR EACH ROW
+EXECUTE FUNCTION compute_notification_message_dedupe_hash();

coderd/database/models.go

@@ -2116,6 +2116,8 @@ type NotificationMessage struct {
 	LeasedUntil            sql.NullTime              `db:"leased_until" json:"leased_until"`
 	NextRetryAfter         sql.NullTime              `db:"next_retry_after" json:"next_retry_after"`
 	QueuedSeconds          sql.NullFloat64           `db:"queued_seconds" json:"queued_seconds"`
+	// Auto-generated by insert/update trigger, used to prevent duplicate notifications from being enqueued on the same day
+	DedupeHash sql.NullString `db:"dedupe_hash" json:"dedupe_hash"`
 }
 
 type NotificationPreference struct {

coderd/database/queries.sql.go

@@ -3274,7 +3274,7 @@ WITH acquired AS (
                              FOR UPDATE OF nm
                                  SKIP LOCKED
                          LIMIT $4)
-            RETURNING id, notification_template_id, user_id, method, status, status_reason, created_by, payload, attempt_count, targets, created_at, updated_at, leased_until, next_retry_after, queued_seconds)
+            RETURNING id, notification_template_id, user_id, method, status, status_reason, created_by, payload, attempt_count, targets, created_at, updated_at, leased_until, next_retry_after, queued_seconds, dedupe_hash)
 SELECT
     -- message
     nm.id,
@@ -3449,14 +3449,15 @@ func (q *sqlQuerier) DeleteOldNotificationMessages(ctx context.Context) error {
 }
 
 const enqueueNotificationMessage = `-- name: EnqueueNotificationMessage :exec
-INSERT INTO notification_messages (id, notification_template_id, user_id, method, payload, targets, created_by)
+INSERT INTO notification_messages (id, notification_template_id, user_id, method, payload, targets, created_by, created_at)
 VALUES ($1,
         $2,
         $3,
         $4::notification_method,
         $5::jsonb,
         $6,
-        $7)
+        $7,
+        $8)
 `
 
 type EnqueueNotificationMessageParams struct {
@@ -3467,6 +3468,7 @@ type EnqueueNotificationMessageParams struct {
 	Payload                json.RawMessage    `db:"payload" json:"payload"`
 	Targets                []uuid.UUID        `db:"targets" json:"targets"`
 	CreatedBy              string             `db:"created_by" json:"created_by"`
+	CreatedAt              time.Time          `db:"created_at" json:"created_at"`
 }
 
 func (q *sqlQuerier) EnqueueNotificationMessage(ctx context.Context, arg EnqueueNotificationMessageParams) error {
@@ -3478,6 +3480,7 @@ func (q *sqlQuerier) EnqueueNotificationMessage(ctx context.Context, arg Enqueue
 		arg.Payload,
 		pq.Array(arg.Targets),
 		arg.CreatedBy,
+		arg.CreatedAt,
 	)
 	return err
 }
@@ -3528,7 +3531,7 @@ func (q *sqlQuerier) FetchNewMessageMetadata(ctx context.Context, arg FetchNewMe
 }
 
 const getNotificationMessagesByStatus = `-- name: GetNotificationMessagesByStatus :many
-SELECT id, notification_template_id, user_id, method, status, status_reason, created_by, payload, attempt_count, targets, created_at, updated_at, leased_until, next_retry_after, queued_seconds
+SELECT id, notification_template_id, user_id, method, status, status_reason, created_by, payload, attempt_count, targets, created_at, updated_at, leased_until, next_retry_after, queued_seconds, dedupe_hash
 FROM notification_messages
 WHERE status = $1
 LIMIT $2::int
@@ -3564,6 +3567,7 @@ func (q *sqlQuerier) GetNotificationMessagesByStatus(ctx context.Context, arg Ge
 			&i.LeasedUntil,
 			&i.NextRetryAfter,
 			&i.QueuedSeconds,
+			&i.DedupeHash,
 		); err != nil {
 			return nil, err
 		}

coderd/database/queries/notifications.sql

@@ -13,14 +13,15 @@ WHERE nt.id = @notification_template_id
   AND u.id = @user_id;
 
 -- name: EnqueueNotificationMessage :exec
-INSERT INTO notification_messages (id, notification_template_id, user_id, method, payload, targets, created_by)
+INSERT INTO notification_messages (id, notification_template_id, user_id, method, payload, targets, created_by, created_at)
 VALUES (@id,
         @notification_template_id,
         @user_id,
         @method::notification_method,
         @payload::jsonb,
         @targets,
-        @created_by);
+        @created_by,
+        @created_at);
 
 -- Acquires the lease for a given count of notification messages, to enable concurrent dequeuing and subsequent sending.
 -- Only rows that aren't already leased (or ones which are leased but have exceeded their lease period) are returned.

coderd/database/unique_constraint.go

@@ -88,6 +88,7 @@ const (
 	UniqueIndexProvisionerDaemonsOrgNameOwnerKey              UniqueConstraint = "idx_provisioner_daemons_org_name_owner_key"                  // CREATE UNIQUE INDEX idx_provisioner_daemons_org_name_owner_key ON provisioner_daemons USING btree (organization_id, name, lower(COALESCE((tags ->> 'owner'::text), ''::text)));
 	UniqueIndexUsersEmail                                     UniqueConstraint = "idx_users_email"                                             // CREATE UNIQUE INDEX idx_users_email ON users USING btree (email) WHERE (deleted = false);
 	UniqueIndexUsersUsername                                  UniqueConstraint = "idx_users_username"                                          // CREATE UNIQUE INDEX idx_users_username ON users USING btree (username) WHERE (deleted = false);
+	UniqueNotificationMessagesDedupeHashIndex                 UniqueConstraint = "notification_messages_dedupe_hash_idx"                       // CREATE UNIQUE INDEX notification_messages_dedupe_hash_idx ON notification_messages USING btree (dedupe_hash);
 	UniqueOrganizationsSingleDefaultOrg                       UniqueConstraint = "organizations_single_default_org"                            // CREATE UNIQUE INDEX organizations_single_default_org ON organizations USING btree (is_default) WHERE (is_default = true);
 	UniqueProvisionerKeysOrganizationIDNameIndex              UniqueConstraint = "provisioner_keys_organization_id_name_idx"                   // CREATE UNIQUE INDEX provisioner_keys_organization_id_name_idx ON provisioner_keys USING btree (organization_id, lower((name)::text));
 	UniqueTemplateUsageStatsStartTimeTemplateIDUserIDIndex    UniqueConstraint = "template_usage_stats_start_time_template_id_user_id_idx"     // CREATE UNIQUE INDEX template_usage_stats_start_time_template_id_user_id_idx ON template_usage_stats USING btree (start_time, template_id, user_id);