From 705a8d0ff3ff02894fafbf3a817d304039d426f9 Mon Sep 17 00:00:00 2001
From: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Date: Tue, 25 May 2021 10:47:45 +0300
Subject: [PATCH] support for ddl_strategy '-vreplication-test-suite', which
 renames both tables on cut-over to names inaccessible to the app, paving the
 way for a reliable test suite

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
---
 go/vt/schema/ddl_strategy.go         | 15 +++++++++++----
 go/vt/vttablet/onlineddl/executor.go | 28 +++++++++++++++++++++-------
 go/vt/vttablet/onlineddl/schema.go   |  5 +++--
 3 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/go/vt/schema/ddl_strategy.go b/go/vt/schema/ddl_strategy.go
index a05d5eabc5..dbc1f2d32b 100644
--- a/go/vt/schema/ddl_strategy.go
+++ b/go/vt/schema/ddl_strategy.go
@@ -28,10 +28,11 @@ var (
 )
 
 const (
-	declarativeFlag      = "declarative"
-	skipTopoFlag         = "skip-topo"
-	singletonFlag        = "singleton"
-	singletonContextFlag = "singleton-context"
+	declarativeFlag       = "declarative"
+	skipTopoFlag          = "skip-topo"
+	singletonFlag         = "singleton"
+	singletonContextFlag  = "singleton-context"
+	vreplicationTestSuite = "vreplication-test-suite"
 )
 
 // DDLStrategy suggests how an ALTER TABLE should run (e.g. "direct", "online", "gh-ost" or "pt-osc")
@@ -129,6 +130,11 @@ func (setting *DDLStrategySetting) IsSingletonContext() bool {
 	return setting.hasFlag(singletonContextFlag)
 }
 
+// IsVreplicationTestSuite checks if strategy options include -vreplicatoin-test-suite
+func (setting *DDLStrategySetting) IsVreplicationTestSuite() bool {
+	return setting.hasFlag(vreplicationTestSuite)
+}
+
 // RuntimeOptions returns the options used as runtime flags for given strategy, removing any internal hint options
 func (setting *DDLStrategySetting) RuntimeOptions() []string {
 	opts, _ := shlex.Split(setting.Options)
@@ -139,6 +145,7 @@ func (setting *DDLStrategySetting) RuntimeOptions() []string {
 		case isFlag(opt, skipTopoFlag):
 		case isFlag(opt, singletonFlag):
 		case isFlag(opt, singletonContextFlag):
+		case isFlag(opt, vreplicationTestSuite):
 		default:
 			validOpts = append(validOpts, opt)
 		}
diff --git a/go/vt/vttablet/onlineddl/executor.go b/go/vt/vttablet/onlineddl/executor.go
index f407d90e95..672e3b0879 100644
--- a/go/vt/vttablet/onlineddl/executor.go
+++ b/go/vt/vttablet/onlineddl/executor.go
@@ -597,13 +597,27 @@ func (e *Executor) cutOverVReplMigration(ctx context.Context, s *VReplStream) er
 
 	// rename tables atomically (remember, writes on source tables are stopped)
 	{
-		parsed := sqlparser.BuildParsedQuery(sqlSwapTables,
-			onlineDDL.Table, swapTable,
-			vreplTable, onlineDDL.Table,
-			swapTable, vreplTable,
-		)
-		if _, err = e.execQuery(ctx, parsed.Query); err != nil {
-			return err
+		if onlineDDL.StrategySetting().IsVreplicationTestSuite() {
+			// this is used in Vitess endtoend testing suite
+			beforeTableName := fmt.Sprintf("%s_before", onlineDDL.Table)
+			afterTableName := fmt.Sprintf("%s_after", onlineDDL.Table)
+			parsed := sqlparser.BuildParsedQuery(sqlRenameTwoTables,
+				onlineDDL.Table, beforeTableName,
+				vreplTable, afterTableName,
+			)
+			if _, err = e.execQuery(ctx, parsed.Query); err != nil {
+				return err
+			}
+		} else {
+			// Normal (non-testing) alter table
+			parsed := sqlparser.BuildParsedQuery(sqlSwapTables,
+				onlineDDL.Table, swapTable,
+				vreplTable, onlineDDL.Table,
+				swapTable, vreplTable,
+			)
+			if _, err = e.execQuery(ctx, parsed.Query); err != nil {
+				return err
+			}
 		}
 	}
 
diff --git a/go/vt/vttablet/onlineddl/schema.go b/go/vt/vttablet/onlineddl/schema.go
index 8ef3d87a98..0d069794bc 100644
--- a/go/vt/vttablet/onlineddl/schema.go
+++ b/go/vt/vttablet/onlineddl/schema.go
@@ -320,8 +320,9 @@ const (
 			_vt.copy_state
 		WHERE vrepl_id=%a
 		`
-	sqlSwapTables  = "RENAME TABLE `%a` TO `%a`, `%a` TO `%a`, `%a` TO `%a`"
-	sqlRenameTable = "RENAME TABLE `%a` TO `%a`"
+	sqlSwapTables      = "RENAME TABLE `%a` TO `%a`, `%a` TO `%a`, `%a` TO `%a`"
+	sqlRenameTwoTables = "RENAME TABLE `%a` TO `%a`, `%a` TO `%a`"
+	sqlRenameTable     = "RENAME TABLE `%a` TO `%a`"
 )
 
 const (