Let SQLite transfer asyncIterables

src/workers/sqlite.ts

@@ -1,8 +1,11 @@
 import * as Comlink from 'comlink';
+import { asyncGeneratorTransferHandler } from 'comlink-async-generator';
 import { CompiledQuery, QueryResult } from 'kysely';
 
 import type { SqliteWorker as _SqliteWorker } from './sqlite.worker.ts';
 
+Comlink.transferHandlers.set('asyncGenerator', asyncGeneratorTransferHandler);
+
 class SqliteWorker {
   #worker: Worker;
   #client: ReturnType<typeof Comlink.wrap<typeof _SqliteWorker>>;
@@ -33,8 +36,12 @@ class SqliteWorker {
     return this.#client.executeQuery(query) as Promise<QueryResult<R>>;
   }
 
-  streamQuery<R>(): AsyncIterableIterator<R> {
-    throw new Error('Streaming queries are not supported in the web worker');
+  async *streamQuery<R>(query: CompiledQuery): AsyncIterableIterator<QueryResult<R>> {
+    await this.#ready;
+
+    for await (const result of await this.#client.streamQuery(query)) {
+      yield result as QueryResult<R>;
+    }
   }
 
   destroy(): Promise<void> {

src/workers/sqlite.worker.ts

@@ -2,6 +2,7 @@
 import { Database as SQLite } from '@db/sqlite';
 import * as Comlink from 'comlink';
 import { CompiledQuery, QueryResult } from 'kysely';
+import { asyncGeneratorTransferHandler } from 'comlink-async-generator';
 
 import '@/sentry.ts';
 
@@ -20,11 +21,22 @@ export const SqliteWorker = {
       insertId: BigInt(db!.lastInsertRowId),
     };
   },
+  async *streamQuery<R>({ sql, parameters }: CompiledQuery): AsyncIterableIterator<QueryResult<R>> {
+    if (!db) throw new Error('Database not open');
+
+    const stmt = db.prepare(sql).bind(...parameters as any[]);
+    for (const row of stmt) {
+      yield {
+        rows: [row],
+      };
+    }
+  },
   destroy() {
     db?.close();
   },
 };
 
+Comlink.transferHandlers.set('asyncGenerator', asyncGeneratorTransferHandler);
 Comlink.expose(SqliteWorker);
 
 self.postMessage(['ready']);