Add db clear command

src/github.com/stellar/horizon/cmd/horizon/db.go

@@ -21,6 +21,22 @@ var dbCmd = &cobra.Command{
 	Short: "commands to manage horizon's postgres db",
 }
 
+var dbClearCmd = &cobra.Command{
+	Use:   "clear",
+	Short: "clears all imported historical data",
+	Run: func(cmd *cobra.Command, args []string) {
+		initConfig()
+		hlog.DefaultLogger.Logger.Level = config.LogLevel
+
+		i := ingestSystem()
+		err := i.ClearAll()
+		if err != nil {
+			hlog.Error(err)
+			os.Exit(1)
+		}
+	},
+}
+
 var dbInitCmd = &cobra.Command{
 	Use:   "init",
 	Short: "install schema",
@@ -101,22 +117,7 @@ var dbReingestCmd = &cobra.Command{
 		initConfig()
 		hlog.DefaultLogger.Logger.Level = config.LogLevel
 
-		hdb, err := db.Open("postgres", config.DatabaseURL)
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		cdb, err := db.Open("postgres", config.StellarCoreDatabaseURL)
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		passphrase := viper.GetString("network-passphrase")
-		if passphrase == "" {
-			log.Fatal("network-passphrase is blank: reingestion requires manually setting passphrase")
-		}
-
-		i := ingest.New(passphrase, config.StellarCoreURL, cdb, hdb)
+		i := ingestSystem()
 		i.SkipCursorUpdate = true
 		logStatus := func(stage string) {
 			count := i.Metrics.IngestLedgerTimer.Count()
@@ -159,11 +160,32 @@ var dbReingestCmd = &cobra.Command{
 
 func init() {
 	dbCmd.AddCommand(dbInitCmd)
+	dbCmd.AddCommand(dbClearCmd)
 	dbCmd.AddCommand(dbMigrateCmd)
 	dbCmd.AddCommand(dbReapCmd)
 	dbCmd.AddCommand(dbReingestCmd)
 }
 
+func ingestSystem() *ingest.System {
+	hdb, err := db.Open("postgres", config.DatabaseURL)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	cdb, err := db.Open("postgres", config.StellarCoreDatabaseURL)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	passphrase := viper.GetString("network-passphrase")
+	if passphrase == "" {
+		log.Fatal("network-passphrase is blank: reingestion requires manually setting passphrase")
+	}
+
+	i := ingest.New(passphrase, config.StellarCoreURL, cdb, hdb)
+	return i
+}
+
 func reingest(i *ingest.System, args []string) (int, error) {
 	if len(args) == 0 {
 		count, err := i.ReingestAll()

src/github.com/stellar/horizon/ingest/ingestion.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"time"
 
+	"math"
+
 	"github.com/guregu/null"
 	sq "github.com/lann/squirrel"
 	"github.com/stellar/go/xdr"
@@ -13,6 +15,11 @@ import (
 	"github.com/stellar/horizon/db2/sqx"
 )
 
+// ClearAll clears the entire history database
+func (ingest *Ingestion) ClearAll() error {
+	return ingest.Clear(0, math.MaxInt64)
+}
+
 // Clear removes a range of data from the history database, exclusive of the end
 // id provided.
 func (ingest *Ingestion) Clear(start int64, end int64) error {

src/github.com/stellar/horizon/ingest/system.go

@@ -11,6 +11,33 @@ import (
 	"github.com/stellar/horizon/toid"
 )
 
+// ClearAll removes all previously ingested historical data from the horizon
+// database.
+func (i *System) ClearAll() error {
+
+	hdb := i.HorizonDB.Clone()
+	ingestion := &Ingestion{DB: hdb}
+
+	err := ingestion.Start()
+	if err != nil {
+		return errors.Wrap(err, "failed to begin ingestion")
+	}
+
+	err = ingestion.ClearAll()
+	if err != nil {
+		return errors.Wrap(err, "failed to clear history tables")
+	}
+
+	err = ingestion.Close()
+	if err != nil {
+		return errors.Wrap(err, "failed to close ingestion")
+	}
+
+	log.Infof("cleared all history")
+
+	return nil
+}
+
 // ReingestAll re-ingests all ledgers
 func (i *System) ReingestAll() (int, error) {
 

src/github.com/stellar/horizon/ingest/system_test.go

@@ -7,6 +7,22 @@ import (
 	"github.com/stellar/horizon/test"
 )
 
+func TestClearAll(t *testing.T) {
+	tt := test.Start(t).Scenario("kahuna")
+	defer tt.Finish()
+	is := sys(tt)
+
+	err := is.ClearAll()
+
+	tt.Require.NoError(err)
+
+	// ensure no ledgers
+	var found int
+	err = tt.HorizonRepo().GetRaw(&found, "SELECT COUNT(*) FROM history_ledgers")
+	tt.Require.NoError(err)
+	tt.Assert.Equal(0, found)
+}
+
 func TestValidation(t *testing.T) {
 	tt := test.Start(t).ScenarioWithoutHorizon("kahuna")
 	defer tt.Finish()