add config option for tx indexing and disable it by default

config/tendermint/config.go

@@ -101,6 +101,8 @@ func GetConfig(rootDir string) cfg.Config {
 	mapConfig.SetDefault("mempool_broadcast", true)
 	mapConfig.SetDefault("mempool_wal_dir", rootDir+"/data/mempool.wal")
 
+	mapConfig.SetDefault("tx_indexer", "none")
+
 	return mapConfig
 }
 

config/tendermint_test/config.go

@@ -107,6 +107,8 @@ func ResetConfig(localPath string) cfg.Config {
 	mapConfig.SetDefault("mempool_broadcast", true)
 	mapConfig.SetDefault("mempool_wal_dir", "")
 
+	mapConfig.SetDefault("tx_indexer", "none")
+
 	logger.SetLogLevel(mapConfig.GetString("log_level"))
 
 	return mapConfig

state/state.go

@@ -44,6 +44,7 @@ type State struct {
 	TxIndexer tx.Indexer `json:"-"` // Transaction indexer.
 }
 
+// Used in tests.
 func LoadState(db dbm.DB) *State {
 	return loadState(db, stateKey)
 }
@@ -132,8 +133,13 @@ func GetState(config cfg.Config, stateDB dbm.DB) *State {
 	}
 
 	// Transaction indexing
-	store := dbm.NewDB("tx_indexer", config.GetString("db_backend"), config.GetString("db_dir"))
-	state.TxIndexer = txindexer.NewKV(store)
+	switch config.GetString("tx_indexer") {
+	case "kv":
+		store := dbm.NewDB("tx_indexer", config.GetString("db_backend"), config.GetString("db_dir"))
+		state.TxIndexer = txindexer.NewKV(store)
+	default:
+		state.TxIndexer = &txindexer.Null{}
+	}
 
 	return state
 }