Throttled transactions return MySQL error code 1041 ER_OUT_OF_RESOURC…

…ES (vitessio#12949)

This error code seems better suited to represent the fact that transactions are
being throttled by the server due to some form of resource contention than the
current code 1203 ER_TOO_MANY_USER_CONNECTIONS.

Signed-off-by: Eduardo J. Ortega U <5791035+ejortegau@users.noreply.github.com>

go/mysql/sql_error.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"regexp"
 	"strconv"
+	"strings"
 
 	"vitess.io/vitess/go/vt/sqlparser"
 	"vitess.io/vitess/go/vt/vterrors"
@@ -135,7 +136,11 @@ func mapToSQLErrorFromErrorCode(err error, msg string) *SQLError {
 		ss = SSAccessDeniedError
 	case vtrpcpb.Code_RESOURCE_EXHAUSTED:
 		num = demuxResourceExhaustedErrors(err.Error())
-		ss = SSClientError
+		// 1041 ER_OUT_OF_RESOURCES has SQLSTATE HYOOO as per https://dev.mysql.com/doc/mysql-errors/8.0/en/server-error-reference.html#error_er_out_of_resources,
+		// so don't override it here in that case.
+		if num != EROutOfResources {
+			ss = SSClientError
+		}
 	case vtrpcpb.Code_UNIMPLEMENTED:
 		num = ERNotSupportedYet
 		ss = SSClientError
@@ -223,6 +228,8 @@ func demuxResourceExhaustedErrors(msg string) int {
 	switch {
 	case isGRPCOverflowRE.Match([]byte(msg)):
 		return ERNetPacketTooLarge
+	case strings.Contains(msg, "Transaction throttled"):
+		return EROutOfResources
 	default:
 		return ERTooManyUserConnections
 	}

go/mysql/sql_error_test.go

@@ -25,7 +25,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestDumuxResourceExhaustedErrors(t *testing.T) {
+func TestDemuxResourceExhaustedErrors(t *testing.T) {
 	type testCase struct {
 		msg  string
 		want int
@@ -42,6 +42,7 @@ func TestDumuxResourceExhaustedErrors(t *testing.T) {
 		// This should be explicitly handled by returning ERNetPacketTooLarge from the execturo directly
 		// and therefore shouldn't need to be teased out of another error.
 		{"in-memory row count exceeded allowed limit of 13", ERTooManyUserConnections},
+		{"rpc error: code = ResourceExhausted desc = Transaction throttled", EROutOfResources},
 	}
 
 	for _, c := range cases {
@@ -151,6 +152,11 @@ func TestNewSQLErrorFromError(t *testing.T) {
 			num: ERNoDb,
 			ss:  SSNoDB,
 		},
+		{
+			err: vterrors.Errorf(vtrpc.Code_RESOURCE_EXHAUSTED, "vttablet: rpc error: code = ResourceExhausted desc = Transaction throttled"),
+			num: EROutOfResources,
+			ss:  SSUnknownSQLState,
+		},
 	}
 
 	for _, tc := range tCases {