Tune SQLite caches and maintain planner statistics

src/lib/server/db/connection.ts

@@ -0,0 +1,12 @@
+import type Database from 'better-sqlite3';
+
+export function tuneConnection(handle: Database.Database, reader = false): void {
+    handle.pragma(`cache_size = -${reader ? 32768 : 131072}`);
+    handle.pragma('temp_store = MEMORY');
+    // mmap is opt-in because the controller data directory can be a network mount.
+    const mmapMiB = Number(process.env.EC_SQLITE_MMAP_MB ?? 0);
+    if (Number.isSafeInteger(mmapMiB) && mmapMiB >= 0 && mmapMiB <= 32768) {
+        handle.pragma(`mmap_size = ${mmapMiB * 1024 * 1024}`);
+    }
+    if (!reader) handle.pragma('journal_size_limit = 67108864');
+}