@@ -81,6 +81,7 @@ The following variables are available on all hooks:
 
 The following variable are available on particular hooks:
 
+- `GH_OST_INSTANT_DDL` is only available in `gh-ost-on-success`. The value is `true` if instant DDL was successful, and `false` if it was not.
 - `GH_OST_COMMAND` is only available in `gh-ost-on-interactive-command`
 - `GH_OST_STATUS` is only available in `gh-ost-on-status`
 - `GH_OST_LAST_BATCH_COPY_ERROR` is only available in `gh-ost-on-batch-copy-retry`
 
@@ -148,8 +148,9 @@ func (this *HooksExecutor) onInteractiveCommand(command string) error {
 	return this.executeHooks(onInteractiveCommand, v)
 }
 
-func (this *HooksExecutor) onSuccess() error {
-	return this.executeHooks(onSuccess)
+func (this *HooksExecutor) onSuccess(instantDDL bool) error {
+	v := fmt.Sprintf("GH_OST_INSTANT_DDL=%t", instantDDL)
+	return this.executeHooks(onSuccess, v)
 }
 
 func (this *HooksExecutor) onFailure() error {
 
@@ -105,6 +105,8 @@ func TestHooksExecutorExecuteHooks(t *testing.T) {
 				require.Equal(t, 50.0, progress)
 			case "GH_OST_TABLE_NAME":
 				require.Equal(t, migrationContext.OriginalTableName, split[1])
+			case "GH_OST_INSTANT_DDL":
+				require.Equal(t, "false", split[1])
 			case "TEST":
 				require.Equal(t, t.Name(), split[1])
 			}
 
@@ -484,7 +484,7 @@ func (this *Migrator) Migrate() (err error) {
 				if err := this.finalCleanup(); err != nil {
 					return nil
 				}
-				if err := this.hooksExecutor.onSuccess(); err != nil {
+				if err := this.hooksExecutor.onSuccess(true); err != nil {
 					return err
 				}
 				this.migrationContext.Log.Infof("Success! table %s.%s migrated instantly", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.OriginalTableName))
@@ -620,7 +620,7 @@ func (this *Migrator) Migrate() (err error) {
 	if err := this.finalCleanup(); err != nil {
 		return nil
 	}
-	if err := this.hooksExecutor.onSuccess(); err != nil {
+	if err := this.hooksExecutor.onSuccess(false); err != nil {
 		return err
 	}
 	this.migrationContext.Log.Infof("Done migrating %s.%s", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.OriginalTableName))
@@ -734,7 +734,7 @@ func (this *Migrator) Revert() error {
 	if err := this.finalCleanup(); err != nil {
 		return nil
 	}
-	if err := this.hooksExecutor.onSuccess(); err != nil {
+	if err := this.hooksExecutor.onSuccess(false); err != nil {
 		return err
 	}
 	this.migrationContext.Log.Infof("Done reverting %s.%s", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.OriginalTableName))
Original file line number	Diff line number	Diff line change
`@@ -148,8 +148,9 @@ func (this *HooksExecutor) onInteractiveCommand(command string) error {`
`148`	`148`	`return this.executeHooks(onInteractiveCommand, v)`
`149`	`149`	`}`
`150`	`150`
`151`		`-func (this *HooksExecutor) onSuccess() error {`
`152`		`- return this.executeHooks(onSuccess)`
	`151`	`+func (this *HooksExecutor) onSuccess(instantDDL bool) error {`
	`152`	`+ v := fmt.Sprintf("GH_OST_INSTANT_DDL=%t", instantDDL)`
	`153`	`+ return this.executeHooks(onSuccess, v)`
`153`	`154`	`}`
`154`	`155`
`155`	`156`	`func (this *HooksExecutor) onFailure() error {`
Original file line number	Diff line number	Diff line change
`@@ -105,6 +105,8 @@ func TestHooksExecutorExecuteHooks(t *testing.T) {`
`105`	`105`	`require.Equal(t, 50.0, progress)`
`106`	`106`	`case "GH_OST_TABLE_NAME":`
`107`	`107`	`require.Equal(t, migrationContext.OriginalTableName, split[1])`
	`108`	`+ case "GH_OST_INSTANT_DDL":`
	`109`	`+ require.Equal(t, "false", split[1])`
`108`	`110`	`case "TEST":`
`109`	`111`	`require.Equal(t, t.Name(), split[1])`
`110`	`112`	`}`
Original file line number	Diff line number	Diff line change
`@@ -484,7 +484,7 @@ func (this *Migrator) Migrate() (err error) {`
`484`	`484`	`if err := this.finalCleanup(); err != nil {`
`485`	`485`	`return nil`
`486`	`486`	`}`
`487`		`- if err := this.hooksExecutor.onSuccess(); err != nil {`
	`487`	`+ if err := this.hooksExecutor.onSuccess(true); err != nil {`
`488`	`488`	`return err`
`489`	`489`	`}`
`490`	`490`	`this.migrationContext.Log.Infof("Success! table %s.%s migrated instantly", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.OriginalTableName))`
`@@ -620,7 +620,7 @@ func (this *Migrator) Migrate() (err error) {`
`620`	`620`	`if err := this.finalCleanup(); err != nil {`
`621`	`621`	`return nil`
`622`	`622`	`}`
`623`		`- if err := this.hooksExecutor.onSuccess(); err != nil {`
	`623`	`+ if err := this.hooksExecutor.onSuccess(false); err != nil {`
`624`	`624`	`return err`
`625`	`625`	`}`
`626`	`626`	`this.migrationContext.Log.Infof("Done migrating %s.%s", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.OriginalTableName))`
`@@ -734,7 +734,7 @@ func (this *Migrator) Revert() error {`
`734`	`734`	`if err := this.finalCleanup(); err != nil {`
`735`	`735`	`return nil`
`736`	`736`	`}`
`737`		`- if err := this.hooksExecutor.onSuccess(); err != nil {`
	`737`	`+ if err := this.hooksExecutor.onSuccess(false); err != nil {`
`738`	`738`	`return err`
`739`	`739`	`}`
`740`	`740`	`this.migrationContext.Log.Infof("Done reverting %s.%s", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.OriginalTableName))`