diff --git a/weed/filer/abstract_sql/abstract_sql_store.go b/weed/filer/abstract_sql/abstract_sql_store.go
index 9aafd448e..dd35112a2 100644
--- a/weed/filer/abstract_sql/abstract_sql_store.go
+++ b/weed/filer/abstract_sql/abstract_sql_store.go
@@ -9,21 +9,28 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"github.com/chrislusf/seaweedfs/weed/util"
 	"strings"
+	"sync"
 )
 
+type SqlGenerator interface {
+	GetSqlInsert(bucket string) string
+	GetSqlUpdate(bucket string) string
+	GetSqlFind(bucket string) string
+	GetSqlDelete(bucket string) string
+	GetSqlDeleteFolderChildren(bucket string) string
+	GetSqlListExclusive(bucket string) string
+	GetSqlListInclusive(bucket string) string
+}
+
 type AbstractSqlStore struct {
-	DB                      *sql.DB
-	SqlInsert               string
-	SqlUpdate               string
-	SqlFind                 string
-	SqlDelete               string
-	SqlDeleteFolderChildren string
-	SqlListExclusive        string
-	SqlListInclusive        string
+	DB *sql.DB
+	SqlGenerator
+	dbs     map[string]bool
+	dbsLock sync.Mutex
 }
 
 const (
-	DEFAULT = "_main"
+	DEFAULT_TABLE = "filemeta"
 )
 
 type TxOrDB interface {
@@ -57,16 +64,53 @@ func (store *AbstractSqlStore) RollbackTransaction(ctx context.Context) error {
 }
 
 func (store *AbstractSqlStore) getTxOrDB(ctx context.Context, fullpath util.FullPath, isForChildren bool) (txOrDB TxOrDB, bucket string, shortPath util.FullPath, err error) {
+
 	shortPath = fullpath
+	bucket = DEFAULT_TABLE
+
 	if tx, ok := ctx.Value("tx").(*sql.Tx); ok {
-		return tx, bucket, shortPath, err
+		txOrDB = tx
+	} else {
+		txOrDB = store.DB
 	}
-	return store.DB, bucket, shortPath, err
+
+	if strings.HasPrefix(string(fullpath), "/buckets/") {
+		return
+	}
+
+	// detect bucket
+	bucketAndObjectKey := string(fullpath)[len("/buckets/"):]
+	t := strings.Index(bucketAndObjectKey, "/")
+	if t < 0 && !isForChildren {
+		return
+	}
+	if t > 0 {
+		bucket = bucketAndObjectKey[:t]
+		shortPath = util.FullPath(bucketAndObjectKey[t:])
+	}
+
+	if isValidBucket(bucket) {
+		store.dbsLock.Lock()
+		defer store.dbsLock.Unlock()
+
+		if store.dbs == nil {
+			store.dbs = make(map[string]bool)
+		}
+
+		if _, found := store.dbs[bucket]; !found {
+			if err = store.createTable(bucket); err != nil {
+				store.dbs[bucket] = true
+			}
+		}
+
+	}
+
+	return
 }
 
 func (store *AbstractSqlStore) InsertEntry(ctx context.Context, entry *filer.Entry) (err error) {
 
-	db, _, shortPath, err := store.getTxOrDB(ctx, entry.FullPath, false)
+	db, bucket, shortPath, err := store.getTxOrDB(ctx, entry.FullPath, false)
 	if err != nil {
 		return fmt.Errorf("findDB %s : %v", entry.FullPath, err)
 	}
@@ -81,7 +125,7 @@ func (store *AbstractSqlStore) InsertEntry(ctx context.Context, entry *filer.Ent
 		meta = util.MaybeGzipData(meta)
 	}
 
-	res, err := db.ExecContext(ctx, store.SqlInsert, util.HashStringToLong(dir), name, dir, meta)
+	res, err := db.ExecContext(ctx, store.GetSqlInsert(bucket), util.HashStringToLong(dir), name, dir, meta)
 	if err == nil {
 		return
 	}
@@ -94,7 +138,7 @@ func (store *AbstractSqlStore) InsertEntry(ctx context.Context, entry *filer.Ent
 	// now the insert failed possibly due to duplication constraints
 	glog.V(1).Infof("insert %s falls back to update: %v", entry.FullPath, err)
 
-	res, err = db.ExecContext(ctx, store.SqlUpdate, meta, util.HashStringToLong(dir), name, dir)
+	res, err = db.ExecContext(ctx, store.GetSqlUpdate(bucket), meta, util.HashStringToLong(dir), name, dir)
 	if err != nil {
 		return fmt.Errorf("upsert %s: %s", entry.FullPath, err)
 	}
@@ -109,7 +153,7 @@ func (store *AbstractSqlStore) InsertEntry(ctx context.Context, entry *filer.Ent
 
 func (store *AbstractSqlStore) UpdateEntry(ctx context.Context, entry *filer.Entry) (err error) {
 
-	db, _, shortPath, err := store.getTxOrDB(ctx, entry.FullPath, false)
+	db, bucket, shortPath, err := store.getTxOrDB(ctx, entry.FullPath, false)
 	if err != nil {
 		return fmt.Errorf("findDB %s : %v", entry.FullPath, err)
 	}
@@ -120,7 +164,7 @@ func (store *AbstractSqlStore) UpdateEntry(ctx context.Context, entry *filer.Ent
 		return fmt.Errorf("encode %s: %s", entry.FullPath, err)
 	}
 
-	res, err := db.ExecContext(ctx, store.SqlUpdate, meta, util.HashStringToLong(dir), name, dir)
+	res, err := db.ExecContext(ctx, store.GetSqlUpdate(bucket), meta, util.HashStringToLong(dir), name, dir)
 	if err != nil {
 		return fmt.Errorf("update %s: %s", entry.FullPath, err)
 	}
@@ -134,13 +178,13 @@ func (store *AbstractSqlStore) UpdateEntry(ctx context.Context, entry *filer.Ent
 
 func (store *AbstractSqlStore) FindEntry(ctx context.Context, fullpath util.FullPath) (*filer.Entry, error) {
 
-	db, _, shortPath, err := store.getTxOrDB(ctx, fullpath, false)
+	db, bucket, shortPath, err := store.getTxOrDB(ctx, fullpath, false)
 	if err != nil {
 		return nil, fmt.Errorf("findDB %s : %v", fullpath, err)
 	}
 
 	dir, name := shortPath.DirAndName()
-	row := db.QueryRowContext(ctx, store.SqlFind, util.HashStringToLong(dir), name, dir)
+	row := db.QueryRowContext(ctx, store.GetSqlFind(bucket), util.HashStringToLong(dir), name, dir)
 
 	var data []byte
 	if err := row.Scan(&data); err != nil {
@@ -162,14 +206,14 @@ func (store *AbstractSqlStore) FindEntry(ctx context.Context, fullpath util.Full
 
 func (store *AbstractSqlStore) DeleteEntry(ctx context.Context, fullpath util.FullPath) error {
 
-	db, _, shortPath, err := store.getTxOrDB(ctx, fullpath, false)
+	db, bucket, shortPath, err := store.getTxOrDB(ctx, fullpath, false)
 	if err != nil {
 		return fmt.Errorf("findDB %s : %v", fullpath, err)
 	}
 
 	dir, name := shortPath.DirAndName()
 
-	res, err := db.ExecContext(ctx, store.SqlDelete, util.HashStringToLong(dir), name, dir)
+	res, err := db.ExecContext(ctx, store.GetSqlDelete(bucket), util.HashStringToLong(dir), name, dir)
 	if err != nil {
 		return fmt.Errorf("delete %s: %s", fullpath, err)
 	}
@@ -189,12 +233,16 @@ func (store *AbstractSqlStore) DeleteFolderChildren(ctx context.Context, fullpat
 		return fmt.Errorf("findDB %s : %v", fullpath, err)
 	}
 
-	if bucket != DEFAULT && shortPath == "/" {
-		store.deleteTable(bucket)
-		return nil
+	if isValidBucket(bucket) && shortPath == "/" {
+		if store.deleteTable(bucket) {
+			store.dbsLock.Lock()
+			delete(store.dbs, bucket)
+			store.dbsLock.Unlock()
+			return nil
+		}
 	}
 
-	res, err := db.ExecContext(ctx, store.SqlDeleteFolderChildren, util.HashStringToLong(string(shortPath)), fullpath)
+	res, err := db.ExecContext(ctx, store.GetSqlDeleteFolderChildren(bucket), util.HashStringToLong(string(shortPath)), fullpath)
 	if err != nil {
 		return fmt.Errorf("deleteFolderChildren %s: %s", fullpath, err)
 	}
@@ -209,14 +257,14 @@ func (store *AbstractSqlStore) DeleteFolderChildren(ctx context.Context, fullpat
 
 func (store *AbstractSqlStore) ListDirectoryPrefixedEntries(ctx context.Context, dirPath util.FullPath, startFileName string, includeStartFile bool, limit int64, prefix string, eachEntryFunc filer.ListEachEntryFunc) (lastFileName string, err error) {
 
-	db, _, shortPath, err := store.getTxOrDB(ctx, dirPath, true)
+	db, bucket, shortPath, err := store.getTxOrDB(ctx, dirPath, true)
 	if err != nil {
 		return lastFileName, fmt.Errorf("findDB %s : %v", dirPath, err)
 	}
 
-	sqlText := store.SqlListExclusive
+	sqlText := store.GetSqlListExclusive(bucket)
 	if includeStartFile {
-		sqlText = store.SqlListInclusive
+		sqlText = store.GetSqlListInclusive(bucket)
 	}
 
 	rows, err := db.QueryContext(ctx, sqlText, util.HashStringToLong(string(shortPath)), startFileName, string(shortPath), prefix+"%", limit+1)
@@ -259,5 +307,14 @@ func (store *AbstractSqlStore) Shutdown() {
 	store.DB.Close()
 }
 
-func (store *AbstractSqlStore) deleteTable(bucket string) {
+func isValidBucket(bucket string) bool {
+	return bucket != DEFAULT_TABLE && bucket != ""
+}
+
+func (store *AbstractSqlStore) createTable(bucket string) error {
+	return nil
+}
+
+func (store *AbstractSqlStore) deleteTable(bucket string) bool {
+	return false
 }
diff --git a/weed/filer/abstract_sql/abstract_sql_store_kv.go b/weed/filer/abstract_sql/abstract_sql_store_kv.go
index 4e56c5db2..03b016c76 100644
--- a/weed/filer/abstract_sql/abstract_sql_store_kv.go
+++ b/weed/filer/abstract_sql/abstract_sql_store_kv.go
@@ -20,7 +20,7 @@ func (store *AbstractSqlStore) KvPut(ctx context.Context, key []byte, value []by
 
 	dirStr, dirHash, name := genDirAndName(key)
 
-	res, err := db.ExecContext(ctx, store.SqlInsert, dirHash, name, dirStr, value)
+	res, err := db.ExecContext(ctx, store.GetSqlInsert(DEFAULT_TABLE), dirHash, name, dirStr, value)
 	if err == nil {
 		return
 	}
@@ -33,7 +33,7 @@ func (store *AbstractSqlStore) KvPut(ctx context.Context, key []byte, value []by
 	// now the insert failed possibly due to duplication constraints
 	glog.V(1).Infof("kv insert falls back to update: %s", err)
 
-	res, err = db.ExecContext(ctx, store.SqlUpdate, value, dirHash, name, dirStr)
+	res, err = db.ExecContext(ctx, store.GetSqlUpdate(DEFAULT_TABLE), value, dirHash, name, dirStr)
 	if err != nil {
 		return fmt.Errorf("kv upsert: %s", err)
 	}
@@ -54,7 +54,7 @@ func (store *AbstractSqlStore) KvGet(ctx context.Context, key []byte) (value []b
 	}
 
 	dirStr, dirHash, name := genDirAndName(key)
-	row := db.QueryRowContext(ctx, store.SqlFind, dirHash, name, dirStr)
+	row := db.QueryRowContext(ctx, store.GetSqlFind(DEFAULT_TABLE), dirHash, name, dirStr)
 
 	err = row.Scan(&value)
 
@@ -78,7 +78,7 @@ func (store *AbstractSqlStore) KvDelete(ctx context.Context, key []byte) (err er
 
 	dirStr, dirHash, name := genDirAndName(key)
 
-	res, err := db.ExecContext(ctx, store.SqlDelete, dirHash, name, dirStr)
+	res, err := db.ExecContext(ctx, store.GetSqlDelete(DEFAULT_TABLE), dirHash, name, dirStr)
 	if err != nil {
 		return fmt.Errorf("kv delete: %s", err)
 	}
diff --git a/weed/filer/mysql/mysql_store.go b/weed/filer/mysql/mysql_store.go
index 70f729fc9..479d2eed1 100644
--- a/weed/filer/mysql/mysql_store.go
+++ b/weed/filer/mysql/mysql_store.go
@@ -15,6 +15,41 @@ const (
 	CONNECTION_URL_PATTERN = "%s:%s@tcp(%s:%d)/%s?charset=utf8"
 )
 
+type SqlGenMysql struct {
+}
+
+var (
+	_ = abstract_sql.SqlGenerator(&SqlGenMysql{})
+)
+
+func (gen *SqlGenMysql) GetSqlInsert(bucket string) string {
+	return "INSERT INTO filemeta (dirhash,name,directory,meta) VALUES(?,?,?,?)"
+}
+
+func (gen *SqlGenMysql) GetSqlUpdate(bucket string) string {
+	return "UPDATE filemeta SET meta=? WHERE dirhash=? AND name=? AND directory=?"
+}
+
+func (gen *SqlGenMysql) GetSqlFind(bucket string) string {
+	return "SELECT meta FROM filemeta WHERE dirhash=? AND name=? AND directory=?"
+}
+
+func (gen *SqlGenMysql) GetSqlDelete(bucket string) string {
+	return "DELETE FROM filemeta WHERE dirhash=? AND name=? AND directory=?"
+}
+
+func (gen *SqlGenMysql) GetSqlDeleteFolderChildren(bucket string) string {
+	return "DELETE FROM filemeta WHERE dirhash=? AND directory=?"
+}
+
+func (gen *SqlGenMysql) GetSqlListExclusive(bucket string) string {
+	return "SELECT NAME, meta FROM filemeta WHERE dirhash=? AND name>? AND directory=? AND name like ? ORDER BY NAME ASC LIMIT ?"
+}
+
+func (gen *SqlGenMysql) GetSqlListInclusive(bucket string) string {
+	return "SELECT NAME, meta FROM filemeta WHERE dirhash=? AND name>=? AND directory=? AND name like ? ORDER BY NAME ASC LIMIT ?"
+}
+
 func init() {
 	filer.Stores = append(filer.Stores, &MysqlStore{})
 }
@@ -43,14 +78,8 @@ func (store *MysqlStore) Initialize(configuration util.Configuration, prefix str
 
 func (store *MysqlStore) initialize(user, password, hostname string, port int, database string, maxIdle, maxOpen,
 	maxLifetimeSeconds int, interpolateParams bool) (err error) {
-	//
-	store.SqlInsert = "INSERT INTO filemeta (dirhash,name,directory,meta) VALUES(?,?,?,?)"
-	store.SqlUpdate = "UPDATE filemeta SET meta=? WHERE dirhash=? AND name=? AND directory=?"
-	store.SqlFind = "SELECT meta FROM filemeta WHERE dirhash=? AND name=? AND directory=?"
-	store.SqlDelete = "DELETE FROM filemeta WHERE dirhash=? AND name=? AND directory=?"
-	store.SqlDeleteFolderChildren = "DELETE FROM filemeta WHERE dirhash=? AND directory=?"
-	store.SqlListExclusive = "SELECT NAME, meta FROM filemeta WHERE dirhash=? AND name>? AND directory=? AND name like ? ORDER BY NAME ASC LIMIT ?"
-	store.SqlListInclusive = "SELECT NAME, meta FROM filemeta WHERE dirhash=? AND name>=? AND directory=? AND name like ? ORDER BY NAME ASC LIMIT ?"
+
+	store.SqlGenerator = &SqlGenMysql{}
 
 	sqlUrl := fmt.Sprintf(CONNECTION_URL_PATTERN, user, password, hostname, port, database)
 	if interpolateParams {
diff --git a/weed/filer/postgres/postgres_store.go b/weed/filer/postgres/postgres_store.go
index 2325568fe..783f27c10 100644
--- a/weed/filer/postgres/postgres_store.go
+++ b/weed/filer/postgres/postgres_store.go
@@ -14,6 +14,41 @@ const (
 	CONNECTION_URL_PATTERN = "host=%s port=%d sslmode=%s connect_timeout=30"
 )
 
+type SqlGenPostgres struct {
+}
+
+var (
+	_ = abstract_sql.SqlGenerator(&SqlGenPostgres{})
+)
+
+func (gen *SqlGenPostgres) GetSqlInsert(bucket string) string {
+	return "INSERT INTO filemeta (dirhash,name,directory,meta) VALUES($1,$2,$3,$4)"
+}
+
+func (gen *SqlGenPostgres) GetSqlUpdate(bucket string) string {
+	return "UPDATE filemeta SET meta=$1 WHERE dirhash=$2 AND name=$3 AND directory=$4"
+}
+
+func (gen *SqlGenPostgres) GetSqlFind(bucket string) string {
+	return "SELECT meta FROM filemeta WHERE dirhash=$1 AND name=$2 AND directory=$3"
+}
+
+func (gen *SqlGenPostgres) GetSqlDelete(bucket string) string {
+	return "DELETE FROM filemeta WHERE dirhash=$1 AND name=$2 AND directory=$3"
+}
+
+func (gen *SqlGenPostgres) GetSqlDeleteFolderChildren(bucket string) string {
+	return "DELETE FROM filemeta WHERE dirhash=$1 AND directory=$2"
+}
+
+func (gen *SqlGenPostgres) GetSqlListExclusive(bucket string) string {
+	return "SELECT NAME, meta FROM filemeta WHERE dirhash=$1 AND name>$2 AND directory=$3 AND name like $4 ORDER BY NAME ASC LIMIT $5"
+}
+
+func (gen *SqlGenPostgres) GetSqlListInclusive(bucket string) string {
+	return "SELECT NAME, meta FROM filemeta WHERE dirhash=$1 AND name>=$2 AND directory=$3 AND name like $4 ORDER BY NAME ASC LIMIT $5"
+}
+
 func init() {
 	filer.Stores = append(filer.Stores, &PostgresStore{})
 }
@@ -41,13 +76,7 @@ func (store *PostgresStore) Initialize(configuration util.Configuration, prefix
 
 func (store *PostgresStore) initialize(user, password, hostname string, port int, database, sslmode string, maxIdle, maxOpen int) (err error) {
 
-	store.SqlInsert = "INSERT INTO filemeta (dirhash,name,directory,meta) VALUES($1,$2,$3,$4)"
-	store.SqlUpdate = "UPDATE filemeta SET meta=$1 WHERE dirhash=$2 AND name=$3 AND directory=$4"
-	store.SqlFind = "SELECT meta FROM filemeta WHERE dirhash=$1 AND name=$2 AND directory=$3"
-	store.SqlDelete = "DELETE FROM filemeta WHERE dirhash=$1 AND name=$2 AND directory=$3"
-	store.SqlDeleteFolderChildren = "DELETE FROM filemeta WHERE dirhash=$1 AND directory=$2"
-	store.SqlListExclusive = "SELECT NAME, meta FROM filemeta WHERE dirhash=$1 AND name>$2 AND directory=$3 AND name like $4 ORDER BY NAME ASC LIMIT $5"
-	store.SqlListInclusive = "SELECT NAME, meta FROM filemeta WHERE dirhash=$1 AND name>=$2 AND directory=$3 AND name like $4 ORDER BY NAME ASC LIMIT $5"
+	store.SqlGenerator = &SqlGenPostgres{}
 
 	sqlUrl := fmt.Sprintf(CONNECTION_URL_PATTERN, hostname, port, sslmode)
 	if user != "" {