From 8e9d294b68b3be22640008cd3429b954e3443ce9 Mon Sep 17 00:00:00 2001
From: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Date: Thu, 18 Jul 2024 15:19:27 +0300
Subject: [PATCH] Support `SHOW VITESS_MIGRATIONS` from inside a transaction
 (#16399)

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
---
 .../scheduler/onlineddl_scheduler_test.go     |  5 ++++
 go/test/endtoend/onlineddl/vtgate_util.go     | 23 +++++++++++++++++++
 go/vt/vttablet/tabletserver/query_executor.go |  6 +++--
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go b/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go
index c059f68b8b7..c0541a04aea 100644
--- a/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go
+++ b/go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go
@@ -572,6 +572,11 @@ func testScheduler(t *testing.T) {
 			}
 		})
 	})
+	t.Run("show vitess_migrations in transaction", func(t *testing.T) {
+		// The function validates there is no error
+		rs := onlineddl.VtgateExecQueryInTransaction(t, &vtParams, "show vitess_migrations", "")
+		assert.NotEmpty(t, rs.Rows)
+	})
 
 	forceCutoverCapable, err := capableOf(capabilities.PerformanceSchemaDataLocksTableCapability) // 8.0
 	require.NoError(t, err)
diff --git a/go/test/endtoend/onlineddl/vtgate_util.go b/go/test/endtoend/onlineddl/vtgate_util.go
index 2cbdbebc2f3..7252edb8096 100644
--- a/go/test/endtoend/onlineddl/vtgate_util.go
+++ b/go/test/endtoend/onlineddl/vtgate_util.go
@@ -66,6 +66,29 @@ func VtgateExecQuery(t *testing.T, vtParams *mysql.ConnParams, query string, exp
 	return qr
 }
 
+// VtgateExecQueryInTransaction runs a query on VTGate using given query params, inside a transaction
+func VtgateExecQueryInTransaction(t *testing.T, vtParams *mysql.ConnParams, query string, expectError string) *sqltypes.Result {
+	t.Helper()
+
+	ctx := context.Background()
+	conn, err := mysql.Connect(ctx, vtParams)
+	require.Nil(t, err)
+	defer conn.Close()
+
+	_, err = conn.ExecuteFetch("begin", -1, true)
+	require.NoError(t, err)
+	qr, err := conn.ExecuteFetch(query, -1, true)
+	if expectError == "" {
+		require.NoError(t, err)
+	} else {
+		require.Error(t, err, "error should not be nil")
+		assert.Contains(t, err.Error(), expectError, "Unexpected error")
+	}
+	_, err = conn.ExecuteFetch("commit", -1, true)
+	require.NoError(t, err)
+	return qr
+}
+
 // VtgateExecDDL executes a DDL query with given strategy
 func VtgateExecDDL(t *testing.T, vtParams *mysql.ConnParams, ddlStrategy string, query string, expectError string) *sqltypes.Result {
 	t.Helper()
diff --git a/go/vt/vttablet/tabletserver/query_executor.go b/go/vt/vttablet/tabletserver/query_executor.go
index 86269050418..9422697f60c 100644
--- a/go/vt/vttablet/tabletserver/query_executor.go
+++ b/go/vt/vttablet/tabletserver/query_executor.go
@@ -203,7 +203,7 @@ func (qre *QueryExecutor) Execute() (reply *sqltypes.Result, err error) {
 	case p.PlanRevertMigration:
 		return qre.execRevertMigration()
 	case p.PlanShowMigrations:
-		return qre.execShowMigrations()
+		return qre.execShowMigrations(nil)
 	case p.PlanShowMigrationLogs:
 		return qre.execShowMigrationLogs()
 	case p.PlanShowThrottledApps:
@@ -308,6 +308,8 @@ func (qre *QueryExecutor) txConnExec(conn *StatefulConnection) (*sqltypes.Result
 		return qre.execLoad(conn)
 	case p.PlanCallProc:
 		return qre.execProc(conn)
+	case p.PlanShowMigrations:
+		return qre.execShowMigrations(conn)
 	}
 	return nil, vterrors.Errorf(vtrpcpb.Code_INTERNAL, "[BUG] %s unexpected plan type", qre.plan.PlanID.String())
 }
@@ -958,7 +960,7 @@ func (qre *QueryExecutor) execRevertMigration() (*sqltypes.Result, error) {
 	return qre.tsv.onlineDDLExecutor.SubmitMigration(qre.ctx, qre.plan.FullStmt)
 }
 
-func (qre *QueryExecutor) execShowMigrations() (*sqltypes.Result, error) {
+func (qre *QueryExecutor) execShowMigrations(conn *StatefulConnection) (*sqltypes.Result, error) {
 	if showStmt, ok := qre.plan.FullStmt.(*sqlparser.Show); ok {
 		return qre.tsv.onlineDDLExecutor.ShowMigrations(qre.ctx, showStmt)
 	}