querylog: return to the default checkpoint cadence

src/storage/querylog_schema.zig

@@ -92,31 +92,6 @@ pub const fingerprint: i32 = blk: {
 
 const set_user_version = std.fmt.comptimePrint("PRAGMA user_version = {d};", .{fingerprint});
 
-/// The WAL checkpoint threshold for every read-write `querylog.db` connection,
-/// in pages (32 MiB at the 4096-byte page size). SQLite's 1000-page default
-/// trips every ~40 min under this workload and rewrites the same hot index and
-/// interior pages into the main database each time; 8192 stretches that to ~5 h
-/// and cuts those in-place rewrites ~8x, which is SD-card write wear this
-/// household appliance does not need to spend.
-///
-/// The durability consequence, stated precisely:
-///
-/// - Commit never fsyncs at `synchronous = NORMAL`; the checkpoint's fsync is
-///   the only guaranteed durability boundary. This moves that boundary from
-///   ~40 min to ~5 h of querylog data under power loss or kernel panic.
-///   Typical loss stays far smaller because of kernel writeback, but that is
-///   not a guarantee.
-/// - Process crash or clean stop loses nothing committed, at any threshold.
-///   Consistency is never at risk: recovery replays the longest valid WAL
-///   prefix atomically.
-/// - 32 MiB is an expectation, not a cap: a pinned reader snapshot stops a
-///   passive checkpoint partway and the WAL overshoots until that reader
-///   finishes. The daily retention `wal_checkpoint(TRUNCATE)` is the backstop
-///   that shrinks the file.
-///
-/// `config.db` keeps the SQLite default: it holds configuration, not a log.
-pub const wal_autocheckpoint_pages: i32 = 8192;
-
 /// Long enough for any path this program will be handed, plus the aside suffix.
 /// A longer path is `error.NameTooLong`, which is what the filesystem calls
 /// would have returned anyway.
@@ -166,7 +141,7 @@ pub fn open(io: std.Io, dir: std.Io.Dir, path: [:0]const u8) Error!OpenResult {
             break :probe recreatable(e) orelse return e;
         const opened = &handle.?;
 
-        db.applyPragmas(opened, .{ .wal_autocheckpoint_pages = wal_autocheckpoint_pages }) catch |e|
+        db.applyPragmas(opened, .{}) catch |e|
             break :probe recreatable(e) orelse return e;
 
         const healthy = quickCheck(opened) catch |e|
@@ -290,7 +265,7 @@ fn deleteSidecars(io: std.Io, dir: std.Io.Dir, path: []const u8) Error!void {
 fn createFresh(path: [:0]const u8) db.Error!db.Db {
     var database = try db.Db.open(path, .{ .mode = .read_write_create });
     errdefer database.close();
-    try db.applyPragmas(&database, .{ .wal_autocheckpoint_pages = wal_autocheckpoint_pages });
+    try db.applyPragmas(&database, .{});
 
     var tx = try db.Tx.begin(&database);
     errdefer tx.rollback();