diff --git a/database/postgis/postgis.go b/database/postgis/postgis.go
index e7e8c1e..9f27412 100644
--- a/database/postgis/postgis.go
+++ b/database/postgis/postgis.go
@@ -111,6 +111,7 @@ func (pg *PostGIS) createSchema(schema string) error {
 	return nil
 }
 
+// Init creates schema and tables, drops existing data.
 func (pg *PostGIS) Init() error {
 	if err := pg.createSchema(pg.Schema); err != nil {
 		return err
@@ -134,6 +135,7 @@ func (pg *PostGIS) Init() error {
 	return nil
 }
 
+// TableNames returns a list of all tables (without prefix).
 func (pg *PostGIS) TableNames() []string {
 	var names []string
 	for name, _ := range pg.Tables {
diff --git a/database/postgis/util.go b/database/postgis/util.go
index fb8494b..a8c9650 100644
--- a/database/postgis/util.go
+++ b/database/postgis/util.go
@@ -106,6 +106,7 @@ func dropTableIfExists(tx *sql.Tx, schema, table string) error {
 	return nil
 }
 
+// rollbackIfTx rollsback transaction if tx is not nil.
 func rollbackIfTx(tx **sql.Tx) {
 	if *tx != nil {
 		if err := tx.Rollback(); err != nil {