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Close-time save ignores wal_checkpoint_threshold(usize::MAX) #476
Description
Problem
The SyncMode::Normal docs (src/db.rs) say that wal_checkpoint_threshold(usize::MAX) means "no per-write flush, no auto-checkpoint, and no close-time checkpoint (the same sentinel also suppresses that)".
Inner::drop does skip its checkpoint for that sentinel. But PersistentFactStorage::drop (src/storage/persistent_facts.rs) calls save() whenever the storage is dirty, so closing the handle still writes every pending fact to the .graph file. The WAL is left next to it, and all of its entries are already checkpointed.
Reproduce
let o = || OpenOptions::new()
.synchronous(SyncMode::Normal)
.wal_checkpoint_threshold(usize::MAX);
{
let db = Minigraf::open_with_options(&p, o()).unwrap();
db.execute("(transact [[:e0 :a0 1]])").unwrap();
db.execute("(transact [[:e0 :a0 2]])").unwrap();
} // drop
// On reopen, replay_wal sees last_checkpointed_tx_count = 2, so the drop saved.Decide
Either:
- make the sentinel suppress the save in
PersistentFactStorage::droptoo, as documented. Benchmarks and bulk loaders rely on that to keep WAL entries pending. - or change the docs (
SyncMode::Normal,OpenOptions::wal_checkpoint_threshold, and the Transaction counter rewinds after reopening next to an already-checkpointed WAL #447 CHANGELOG wording) to say that close always saves.
Found while writing the #385 model-based test. Its Crash step copies the files while the handle is open, because a drop cannot leave a WAL to replay.
Activity
test(db): cover the in-memory arm of the #476 drop path
Merge pull request #526 from project-minigraf/fix/476-sentinel-drop-save
adityamukho commentedon Oct 10, 2026
Fixed on v3 by #526 (bc7a6b6).
Merge pull request #540 from project-minigraf/fix/457-476-v2-backport
Merge pull request #541 from project-minigraf/docs/457-476-backport-note
adityamukho commentedon Oct 11, 2026
Backported to v2.x in #540 (merged to
main, 99410b1); ships in the next v2.x patch release.release: v2.0.5
ci(bench): compare each run with the last 30 runs, not all history (#568