1 files changed, 16 insertions, 2 deletions
diff --git a/ethdb/interface.go b/ethdb/interface.go
index f4b787a52..99a5b770d 100644
--- a/ethdb/interface.go
+++ b/ethdb/interface.go
@@ -16,15 +16,29 @@
 
 package ethdb
 
-type Database interface {
+// Code using batches should try to add this much data to the batch.
+// The value was determined empirically.
+const IdealBatchSize = 100 * 1024
+
+// Putter wraps the database write operation supported by both batches and regular databases.
+type Putter interface {
 	Put(key []byte, value []byte) error
+}
+
+// Database wraps all database operations. All methods are safe for concurrent use.
+type Database interface {
+	Putter
 	Get(key []byte) ([]byte, error)
+	Has(key []byte) (bool, error)
 	Delete(key []byte) error
 	Close()
 	NewBatch() Batch
 }
 
+// Batch is a write-only database that commits changes to its host database
+// when Write is called. Batch cannot be used concurrently.
 type Batch interface {
-	Put(key, value []byte) error
+	Putter
+	ValueSize() int // amount of data in the batch
 	Write() error
 }