Keep startup database rebuilds out of memory

tests/helpers/vacuum-memory.ts

@@ -0,0 +1,23 @@
+import Database from 'better-sqlite3';
+import { enableIncrementalVacuum } from '../../src/lib/server/db/retention-clocks.js';
+
+// Run in a separate process so native SQLite memory, not just V8's heap, is measured.
+const handle = new Database(process.argv[2]);
+try {
+    handle.pragma('journal_mode = WAL');
+    handle.pragma('cache_size = -16384');
+    handle.exec('CREATE TABLE records(id INTEGER PRIMARY KEY, content BLOB)');
+    const insert = handle.prepare('INSERT INTO records(content) VALUES(zeroblob(1048576))');
+    handle.transaction(() => { for (let i = 0; i < 256; i++) insert.run(); })();
+    handle.pragma('wal_checkpoint(TRUNCATE)');
+    handle.pragma('shrink_memory');
+    // Reproduce the dangerous caller settings. The rebuild must override these.
+    handle.pragma('temp_store = MEMORY');
+    handle.pragma('cache_size = -131072');
+    const beforeKiB = process.resourceUsage().maxRSS;
+    enableIncrementalVacuum(handle);
+    console.log(JSON.stringify({ beforeKiB, peakKiB: process.resourceUsage().maxRSS,
+        vacuum: handle.pragma('auto_vacuum', { simple: true }),
+        integrity: handle.pragma('quick_check', { simple: true }),
+        rows: handle.prepare('SELECT COUNT(*) n FROM records').get() }));
+} finally { handle.close(); }