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Populate snapshot_blobs for dedup-referenced blobs at completion

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The bug: fully-deduplicated snapshots (every chunk already in storage
from a prior run) had an empty snapshot_blobs table. The metadata-
export pipeline then dropped all blob/blob_chunks rows from the
exported database, leaving file_chunks references to chunks whose
blobs were no longer recorded. Restore fails on every file with
"chunk X not found in any blob".

Fix: at CompleteSnapshot time, run an INSERT OR IGNORE that links
every blob holding a chunk referenced by this snapshot's files into
snapshot_blobs. New blobs uploaded during the snapshot are already
recorded (no-op for them); dedup-referenced blobs are added.

The cleanup query in deleteOrphanedBlobs already restricts to
snapshot_blobs entries for the current snapshot — so once
snapshot_blobs is correctly populated, the exported database
contains the full set of blob/blob_chunks rows needed for restore.

Regression test: TestDedupOnlySnapshotRestores creates two
identical snapshots (the second uploads zero new blobs) and
restores the second. Without the fix, restore fails on every file.
This commit is contained in:
Jeffrey Paul
2026-06-17 06:05:52 +02:00
parent f1ce085972
commit 132f7149ca
3 changed files with 166 additions and 2 deletions
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14
internal/snapshot/snapshot.go
View File

@@ -180,10 +180,20 @@ func (sm *SnapshotManager) UpdateSnapshotStatsExtended(ctx context.Context, snap
})
}
// CompleteSnapshot marks a snapshot as completed and exports its metadata
// CompleteSnapshot marks a snapshot as completed and ensures snapshot_blobs
// is populated with every blob holding any chunk referenced by the
// snapshot's files (including deduplicated blobs uploaded by prior
// snapshots). Without this, fully-deduplicated snapshots are unrestorable.
func (sm *SnapshotManager) CompleteSnapshot(ctx context.Context, snapshotID string) error {
// Mark the snapshot as completed
err := sm.repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
added, err := sm.repos.Snapshots.PopulateReferencedBlobs(ctx, tx, snapshotID)
if err != nil {
return err
}
if added > 0 {
log.Info("Populated snapshot_blobs with dedup-referenced blobs",
"snapshot_id", snapshotID, "added", added)
}
return sm.repos.Snapshots.MarkComplete(ctx, tx, snapshotID)
})