lib/logstorage: do not persist streamIDCache, since it may go out of sync with partition directories, which can be changed manually between VictoriaLogs restarts

Partition directories can be manually deleted and copied from another sources such as backups or other VitoriaLogs instances.
In this case the persisted cache becomes out of sync with partitions. This can result in missing index entries
during data ingestion or in incorrect results during querying. So it is better to do not persist caches.
This shouldn't hurt VictoriaLogs performance just after the restart too much, since its caches usually contain
small amounts of data, which can be quickly re-populated from the persisted data.

lib/logstorage/filenames.go

@@ -17,10 +17,7 @@ const (
 	metadataFilename = "metadata.json"
 	partsFilename    = "parts.json"
 
-	streamIDCacheFilename = "stream_id.bin"
-
 	indexdbDirname    = "indexdb"
 	datadbDirname     = "datadb"
-	cacheDirname      = "cache"
 	partitionsDirname = "partitions"
 )

lib/logstorage/storage.go

@@ -244,9 +244,8 @@ func MustOpenStorage(path string, cfg *StorageConfig) *Storage {
 
 	// Load caches
 	mem := memory.Allowed()
-	streamIDCachePath := filepath.Join(path, cacheDirname, streamIDCacheFilename)
-	streamIDCache := workingsetcache.Load(streamIDCachePath, mem/16)
 
+	streamIDCache := workingsetcache.New(mem / 16)
 	filterStreamCache := workingsetcache.New(mem / 10)
 
 	s := &Storage{
@@ -457,11 +456,13 @@ func (s *Storage) MustClose() {
 	s.partitions = nil
 	s.ptwHot = nil
 
-	// Save caches
+	// Stop caches
-	streamIDCachePath := filepath.Join(s.path, cacheDirname, streamIDCacheFilename)
+
-	if err := s.streamIDCache.Save(streamIDCachePath); err != nil {
+	// Do not persist caches, since they may become out of sync with partitions
-		logger.Panicf("FATAL: cannot save streamID cache to %q: %s", streamIDCachePath, err)
+	// if partitions are deleted, restored from backups or copied from other sources
-	}
+	// between VictoriaLogs restarts. This may result in various issues
+	// during data ingestion and querying.
+
 	s.streamIDCache.Stop()
 	s.streamIDCache = nil