Add db key

pkg/key/key.go

+package key
+
+import (
+	"fmt"
+)
+
+const (
+	blockKey           = "block-"
+	blockHashKey       = "block-hash-"
+	blockHeightKey     = "block-height-"
+	blockTxSetKey      = "block-tx-set-"
+	interchainMetaKey  = "interchain-meta-"
+	receiptKey         = "receipt-"
+	transactionKey     = "tx-"
+	transactionMetaKey = "tx-meta-"
+	chainMetaKey       = "chain-meta"
+	accountKey         = "account-"
+	codeKey            = "code-"
+	journalKey         = "journal-"
+)
+
+func CompositeKey(prefix string, value interface{}) []byte {
+	return append([]byte(prefix), []byte(fmt.Sprintf("%v", value))...)
+}

pkg/key/key_test.go

+package key
+
+import (
+	"testing"
+
+	"github.com/magiconair/properties/assert"
+)
+
+func TestCompositeKey(t *testing.T) {
+	assert.Equal(t, CompositeKey(blockKey, 1), []byte("block-1"))
+	assert.Equal(t, CompositeKey(blockHashKey, "0x112233"), []byte("block-hash-0x112233"))
+	assert.Equal(t, CompositeKey(transactionKey, "0x112233"), []byte("tx-0x112233"))
+}