CODEWITHSUNDEEP
databasegodatabase-designleveldb
GraphicalDot
GraphicalDot

Reputation: 2831

Auto adjusting levelDB disk space?

I am using Go to store keys/values in the levelDB database. While i am inserting new key/values in the LevelDB, I checked the disk space used by leveldbfile Folder, it increases and then decreases in cycles.

  ➜  loomio git:(master) ✗ du -h leveldbfile
  7.4M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  1.2M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  8.3M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  8.4M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  6.0M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  3.6M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
   11M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
   10M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  3.7M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  1.2M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  8.3M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  6.0M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  3.7M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  1.4M  leveldbfile
  ➜  loomio git:(master) ✗ du -h leveldbfile
  8.5M  leveldbfile

The code for Storing email, password for users is 

        func AddUser(dbSession config.Database, user *models.User) (string, error) {

            user_id := uuid.NewV4()
            user.UserID = user_id.String()
            ok := RetreiveSecondaryIndex(dbSession, user.Email)
            if ok {
                log.Println("This is the user id found in secondary index", ok)
                return "", errors.New("The email is already registered")

            }

            var network bytes.Buffer // Stand-in for a network connection
            enc := gob.NewEncoder(&network)

            err := enc.Encode(user)
            if err != nil {
                log.Println("Error in encoding gob")
                return "", err
            }


            err = dbSession.DBSession.Put([]byte(user.UserID), network.Bytes(), nil)
            //dberr := userCollection.Insert(user)
            fmt.Println(err)
            if err != nil {
                log.Println(err)
                return "", err
            }

            AddSecondaryIndex(dbSession, user.Username, user.Email)

            return user.UserID, nil
        }

Why is LevelDB readjusting its disk space and on what basis?

Upvotes: 0

Views: 419

Answers (1)

wouter bolsterlee
wouter bolsterlee

Reputation: 4037

LevelDB compacts SST files in a background thread while the database grows. Since these files are immutable, this works by creating new ones, and then removing the old ones. Hence, this ‘compaction’ step requires (temporarily) extra disk space.

Upvotes: 1

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