code re-org and bugfix hanging hourly snapshot

internal/tasks/inventoryHelpers.go

@@ -44,10 +44,11 @@ func boolStringFromInterface(value interface{}) string {
 // latestHourlySnapshotBefore finds the most recent hourly snapshot table prior to the given time, skipping empty tables.
 func latestHourlySnapshotBefore(ctx context.Context, dbConn *sqlx.DB, cutoff time.Time) (string, error) {
 	rows, err := dbConn.QueryxContext(ctx, `
-SELECT table_name, snapshot_time
+SELECT table_name, snapshot_time, snapshot_count
 FROM snapshot_registry
-WHERE snapshot_type = 'hourly' AND snapshot_time < ?
+WHERE snapshot_type = 'hourly' AND snapshot_time < ? AND snapshot_count > 0
 ORDER BY snapshot_time DESC
+LIMIT 50
 `, cutoff.Unix())
 	if err != nil {
 		return "", err
@@ -57,17 +58,18 @@ ORDER BY snapshot_time DESC
 	for rows.Next() {
 		var name string
 		var ts int64
-		if scanErr := rows.Scan(&name, &ts); scanErr != nil {
+		var count int64
+		if scanErr := rows.Scan(&name, &ts, &count); scanErr != nil {
 			continue
 		}
 		if err := db.ValidateTableName(name); err != nil {
 			continue
 		}
-		hasRows, err := db.TableHasRows(ctx, dbConn, name)
-		if err != nil {
-			continue
+		// Rely on snapshot_count to avoid costly table scans; fall back to a cheap row check only if count is zero.
+		if count > 0 {
+			return name, nil
 		}
-		if hasRows {
+		if hasRows, _ := db.TableHasRows(ctx, dbConn, name); hasRows {
 			return name, nil
 		}
 	}