feat(webapp): add option to disable PostgreSQL task-event writes

Adds EVENT_REPOSITORY_POSTGRES_WRITES_DISABLED (default off). When enabled, the
task-event store skips all PostgreSQL writes, for deployments that store task
events in ClickHouse (EVENT_REPOSITORY_DEFAULT_STORE=clickhouse_v2). Reads are
unaffected, so existing events stay readable.

Author: ericallam

.server-changes/disable-postgres-task-event-writes.md

@@ -0,0 +1,6 @@
+---
+area: webapp
+type: feature
+---
+
+Added `EVENT_REPOSITORY_POSTGRES_WRITES_DISABLED` to skip all PostgreSQL task-event writes for deployments that store task events in ClickHouse. Leave it off unless `EVENT_REPOSITORY_DEFAULT_STORE` is `clickhouse_v2`, otherwise task events are lost.

apps/webapp/app/env.server.ts

@@ -1828,6 +1828,7 @@ const EnvironmentSchema = z
       .enum(["postgres", "clickhouse", "clickhouse_v2"])
       .default("postgres"),
     EVENT_REPOSITORY_DEBUG_LOGS_DISABLED: BoolEnv.default(false),
+    EVENT_REPOSITORY_POSTGRES_WRITES_DISABLED: BoolEnv.default(false),
     EVENTS_CLICKHOUSE_MAX_TRACE_SUMMARY_VIEW_COUNT: z.coerce.number().int().default(25_000),
     EVENTS_CLICKHOUSE_MAX_TRACE_DETAILED_SUMMARY_VIEW_COUNT: z.coerce.number().int().default(5_000),
     EVENTS_CLICKHOUSE_MAX_LIVE_RELOADING_SETTING: z.coerce.number().int().default(2000),

apps/webapp/app/v3/eventRepository/eventRepository.server.ts

@@ -120,7 +120,11 @@ export class EventRepository implements IEventRepository {
     this._tracer = _config.tracer ?? trace.getTracer("eventRepo", "0.0.1");
 
     // Instantiate the store using the partitioning flag.
-    this.taskEventStore = new TaskEventStore(db, readReplica);
+    this.taskEventStore = new TaskEventStore(
+      db,
+      readReplica,
+      env.EVENT_REPOSITORY_POSTGRES_WRITES_DISABLED
+    );
   }
 
   #createableEventToPrismaEvent(event: CreateEventInput): Prisma.TaskEventCreateManyInput {

apps/webapp/app/v3/taskEventStore.server.ts

@@ -59,13 +59,17 @@ export function getTaskEventStore(): TaskEventStoreTable {
 export class TaskEventStore {
   constructor(
     private db: PrismaClient,
-    private readReplica: PrismaReplicaClient
+    private readReplica: PrismaReplicaClient,
+    private writesDisabled: boolean = false
   ) {}
 
   /**
    * Insert one record.
    */
   async create(table: TaskEventStoreTable, data: Prisma.TaskEventCreateInput) {
+    if (this.writesDisabled) {
+      return;
+    }
     if (table === "taskEventPartitioned") {
       return await this.db.taskEventPartitioned.create({ data });
     } else {
@@ -77,6 +81,9 @@ export class TaskEventStore {
    * Insert many records.
    */
   async createMany(table: TaskEventStoreTable, data: Prisma.TaskEventCreateManyInput[]) {
+    if (this.writesDisabled) {
+      return { count: 0 };
+    }
     if (table === "taskEventPartitioned") {
       return await this.db.taskEventPartitioned.createMany({ data });
     } else {

docs/self-hosting/env/webapp.mdx

@@ -135,6 +135,7 @@ mode: "wide"
 | `SERVER_OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT`  | No       | 8192                  | OTel span attribute value length limit.                                                                            |
 | **Task events**                                  |          |                       |                                                                                                                    |
 | `EVENT_REPOSITORY_DEFAULT_STORE`                 | No       | postgres              | Where to store task events. Set to `clickhouse_v2` to store in ClickHouse (recommended for production).            |
+| `EVENT_REPOSITORY_POSTGRES_WRITES_DISABLED`      | No       | 0                     | Skip all PostgreSQL task-event writes (set to `1`). Only enable when `EVENT_REPOSITORY_DEFAULT_STORE` is `clickhouse_v2`, otherwise task events are lost. |
 | **Realtime**                                     |          |                       |                                                                                                                    |
 | `REALTIME_STREAM_VERSION`                        | No       | v1                    | Stream version exposed to tasks via the `TRIGGER_REALTIME_STREAM_VERSION` variable. Distinct from `REALTIME_STREAMS_DEFAULT_VERSION`. One of `v1`, `v2`. |
 | `REALTIME_STREAM_MAX_LENGTH`                     | No       | 1000                  | Realtime stream max length.                                                                                        |