allow SHOW to stop blocking queries after a VT15001

Signed-off-by: Florent Poinsard <florent.poinsard@outlook.fr>

go/test/endtoend/reparent/newfeaturetest/reparent_in_tx_test.go

@@ -68,7 +68,7 @@ func testExecuteError(t *testing.T, conn *mysql.Conn, clusterInstance *cluster.L
 		_, err = conn.ExecuteFetch("select * from vt_insert_test", 1, false)
 		require.ErrorContains(t, err, "VT15002")
 
-		_, err = conn.ExecuteFetch("rollback", 0, false)
+		_, err = conn.ExecuteFetch("show warnings", 0, false)
 		require.NoError(t, err)
 		executeDone <- true
 	}()

go/vt/vterrors/code.go

@@ -121,8 +121,8 @@ var (
 	VT14004 = errorWithoutState("VT14004", vtrpcpb.Code_UNAVAILABLE, "cannot find keyspace for: %s", "The specified keyspace could not be found.")
 	VT14005 = errorWithoutState("VT14005", vtrpcpb.Code_UNAVAILABLE, "cannot lookup sidecar database for keyspace: %s", "Failed to read sidecar database identifier.")
 
-	VT15001 = errorWithNoCode("VT15001", "transient transaction error, please issue a ROLLBACK and retry the transaction: %s", "The opened transaction must be ROLLBACK by the application and re-tried.")
-	VT15002 = errorWithoutState("VT15002", vtrpcpb.Code_FAILED_PRECONDITION, "previous transaction failed fatally: issue a ROLLBACK query in order to acknowledge the failed transaction", "This error appears after a VT15001 error was sent back to the client, future queries on the same session will fail until a ROLLBACK is explicitly sent to VTGate.")
+	VT15001 = errorWithNoCode("VT15001", "transient transaction error, please issue a ROLLBACK or SHOW WARNINGS and retry the transaction: %s", "The opened transaction must be ROLLBACK by the application and re-tried.")
+	VT15002 = errorWithoutState("VT15002", vtrpcpb.Code_FAILED_PRECONDITION, "previous transaction failed fatally: issue a ROLLBACK or SHOW WARNINGS query in order to acknowledge the failed transaction", "This error appears after a VT15001 error was sent back to the client, future queries on the same session will fail until the client acknowledge the situation by a sending a ROLLBACK or SHOW WARNINGS query.")
 
 	// Errors is a list of errors that must match all the variables
 	// defined above to enable auto-documentation of error codes.

go/vt/vtgate/executor.go

@@ -625,7 +625,6 @@ func (e *Executor) handleRollback(ctx context.Context, safeSession *econtext.Saf
 	e.updateQueryCounts("Rollback", "", "", int64(logStats.ShardQueries))
 	err := e.txConn.Rollback(ctx, safeSession)
 	logStats.CommitTime = time.Since(execStart)
-	safeSession.SetErrorUntilRollback(false) // We have executed a ROLLBACK, if applicable: we can stop blocking queries on this session
 	return &sqltypes.Result{}, err
 }
 

go/vt/vtgate/plan_execute.go

@@ -152,8 +152,8 @@ func (e *Executor) newExecute(
 		ctx, cancel = vcursor.GetContextWithTimeOut(ctx)
 		defer cancel()
 
-		// If we have previously issued a VT15001 error, we block every queries on this session until we receive a ROLLBACK.
-		if plan.Type != sqlparser.StmtRollback && safeSession.IsErrorUntilRollback() {
+		// If we have previously issued a VT15001 error, we block every queries on this session until we receive a ROLLBACK or "show warnings".
+		if shouldBlockQuery(plan, safeSession) {
 			return vterrors.VT15002()
 		}
 
@@ -444,3 +444,14 @@ func (e *Executor) logPlanningFinished(logStats *logstats.LogStats, plan *engine
 	logStats.PlanTime = execStart.Sub(logStats.StartTime)
 	return execStart
 }
+
+func shouldBlockQuery(plan *engine.Plan, safeSession *econtext.SafeSession) bool {
+	block := safeSession.IsErrorUntilRollback()
+	if plan.Type != sqlparser.StmtRollback && plan.Type != sqlparser.StmtShow && block {
+		return true
+	}
+	if block {
+		safeSession.SetErrorUntilRollback(false)
+	}
+	return false
+}