Merge cockroachdb#108133 cockroachdb#108461

108133: sql: release save point did not retry for two version invariant errors r=fqazi a=fqazi

Previously, when release save point was issued for cockroach_restart this would drive a commit, which could run into retryable errors. Like the two version invariant error, which is not tagged as a user facing re triable error, so the client doesn't know to retry. To address this, this patch converts two version invariant errors in this case into user facing retryable errors;

Fixes: cockroachdb#107171

Release note (bug fix): Release save point could incorrectly emit "cannot publish new versions for descriptors" instead of a retryable error to applications.

108461: sql: fix recently introduced minor bug around PREPARE r=yuzefovich a=yuzefovich

In just merged 4a3e787, we had a minor bug that in case `addPreparedStmt` call fails, we don't restore the original placeholders, which can then lead to panics.

Fixes: cockroachdb#108421.

Release note: None

Co-authored-by: Faizan Qazi <[email protected]>
Co-authored-by: Yahor Yuzefovich <[email protected]>

Author: 3 people

pkg/sql/catalog/lease/lease_test.go

@@ -1479,6 +1479,121 @@ CREATE TABLE t.kv (k CHAR PRIMARY KEY, v CHAR);
 	}
 }
 
+// Tests that when a transaction has already returned results
+// to the user and the transaction continues on to make a schema change,
+// whenever the table lease two version invariant is violated and the
+// transaction needs to be restarted, a retryable error is returned to the
+// user. This specific version validations that release savepoint does the
+// same with cockroach_restart, which commits on release.
+func TestTwoVersionInvariantRetryErrorWitSavePoint(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	var violations int64
+	var params base.TestServerArgs
+	params.Knobs = base.TestingKnobs{
+		// Disable execution of schema changers after the schema change
+		// transaction commits. This is to prevent executing the default
+		// WaitForOneVersion() code that holds up a schema change
+		// transaction until the new version has been published to the
+		// entire cluster.
+		SQLSchemaChanger: &sql.SchemaChangerTestingKnobs{
+			SchemaChangeJobNoOp: func() bool {
+				return true
+			},
+			TwoVersionLeaseViolation: func() {
+				atomic.AddInt64(&violations, 1)
+			},
+		},
+	}
+	s, sqlDB, kvDB := serverutils.StartServer(t, params)
+	defer s.Stopper().Stop(context.Background())
+
+	if _, err := sqlDB.Exec(`
+CREATE DATABASE t;
+CREATE TABLE t.kv (k CHAR PRIMARY KEY, v CHAR);
+INSERT INTO t.kv VALUES ('a', 'b');
+`); err != nil {
+		t.Fatal(err)
+	}
+
+	tableDesc := desctestutils.TestingGetPublicTableDescriptor(kvDB, keys.SystemSQLCodec, "t", "kv")
+	if tableDesc.GetVersion() != 1 {
+		t.Fatalf("invalid version %d", tableDesc.GetVersion())
+	}
+
+	tx, err := sqlDB.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Grab a lease on the table.
+	rows, err := tx.Query("SELECT * FROM t.kv")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Modify the table descriptor increments the version.
+	if _, err := sqlDB.Exec(`ALTER TABLE t.kv RENAME to t.kv1`); err != nil {
+		t.Fatal(err)
+	}
+
+	txRetry, err := sqlDB.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = txRetry.Exec("SAVEPOINT cockroach_restart;")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Read some data using the transaction so that it cannot be
+	// retried internally
+	rows, err = txRetry.Query(`SELECT 1`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := txRetry.Exec(`ALTER TABLE t.kv1 RENAME TO t.kv2`); err != nil {
+		t.Fatal(err)
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		// This can hang waiting for one version before tx.Commit() is
+		// called below, so it is executed in another goroutine.
+		_, err := txRetry.Exec("RELEASE SAVEPOINT cockroach_restart;")
+		if !testutils.IsError(err,
+			fmt.Sprintf(`TransactionRetryWithProtoRefreshError: cannot publish new versions for descriptors: \[\{kv1 %d 1\}\], old versions still in use`, tableDesc.GetID()),
+		) {
+			t.Errorf("err = %v", err)
+		}
+		err = txRetry.Rollback()
+		if err != nil {
+			t.Errorf("err = %v", err)
+		}
+	}()
+
+	// Make sure that txRetry does violate the two version lease invariant.
+	testutils.SucceedsSoon(t, func() error {
+		if atomic.LoadInt64(&violations) == 0 {
+			return errors.Errorf("didnt retry schema change")
+		}
+		return nil
+	})
+	// Commit the first transaction, unblocking txRetry.
+	if err := tx.Commit(); err != nil {
+		t.Fatal(err)
+	}
+	wg.Wait()
+}
+
 // Tests that when a transaction has already returned results
 // to the user and the transaction continues on to make a schema change,
 // whenever the table lease two version invariant is violated and the

pkg/sql/conn_executor.go

@@ -3284,6 +3284,28 @@ func errIsRetriable(err error) bool {
 		descs.IsTwoVersionInvariantViolationError(err)
 }
 
+// convertRetriableErrorIntoUserVisibleError converts internal retriable
+// errors into external, so that the client goes and retries this
+// transaction. One example of this is two version invariant errors, which
+// happens when a schema change is waiting for a schema change transition to
+// propagate. When this happens, we either need to retry externally or internally,
+// depending on if we are in an explicit transaction.
+func (ex *connExecutor) convertRetriableErrorIntoUserVisibleError(
+	ctx context.Context, origErr error,
+) (modifiedErr error, err error) {
+	if descs.IsTwoVersionInvariantViolationError(origErr) {
+		if resetErr := ex.resetTransactionOnSchemaChangeRetry(ctx); resetErr != nil {
+			return nil, resetErr
+		}
+		// Generating a forced retry error here, right after resetting the
+		// transaction is not exactly necessary, but it's a sound way to
+		// generate the only type of ClientVisibleRetryError we have.
+		return ex.state.mu.txn.GenerateForcedRetryableError(ctx, redact.Sprint(origErr)), nil
+	}
+	// Return the original error, this error will not be surfaced to the user.
+	return origErr, nil
+}
+
 // makeErrEvent takes an error and returns either an eventRetriableErr or an
 // eventNonRetriableErr, depending on the error type.
 func (ex *connExecutor) makeErrEvent(err error, stmt tree.Statement) (fsm.Event, fsm.EventPayload) {

pkg/sql/conn_executor_exec.go

@@ -903,16 +903,18 @@ func (ex *connExecutor) execStmtInOpenState(
 		// PREPARE statement itself.
 		oldPlaceholders := p.extendedEvalCtx.Placeholders
 		p.extendedEvalCtx.Placeholders = nil
+		defer func() {
+			// The call to addPreparedStmt changed the planner stmt to the
+			// statement being prepared. Set it back to the PREPARE statement,
+			// so that it's logged correctly.
+			p.stmt = stmt
+			p.extendedEvalCtx.Placeholders = oldPlaceholders
+		}()
 		if _, err := ex.addPreparedStmt(
 			ctx, name, prepStmt, typeHints, rawTypeHints, PreparedStatementOriginSQL,
 		); err != nil {
 			return makeErrEvent(err)
 		}
-		// The call to addPreparedStmt changed the planner stmt to the statement
-		// being prepared. Set it back to the PREPARE statement, so that it's
-		// logged correctly.
-		p.stmt = stmt
-		p.extendedEvalCtx.Placeholders = oldPlaceholders
 		return nil, nil, nil
 	}
 
@@ -1307,14 +1309,12 @@ func (ex *connExecutor) commitSQLTransaction(
 	}
 	ex.phaseTimes.SetSessionPhaseTime(sessionphase.SessionStartTransactionCommit, timeutil.Now())
 	if err := commitFn(ctx); err != nil {
-		if descs.IsTwoVersionInvariantViolationError(err) {
-			if resetErr := ex.resetTransactionOnSchemaChangeRetry(ctx); resetErr != nil {
-				return ex.makeErrEvent(err, ast)
-			}
-			// Generating a forced retry error here, right after resetting the
-			// transaction is not exactly necessary, but it's a sound way to
-			// generate the only type of ClientVisibleRetryError we have.
-			err = ex.state.mu.txn.GenerateForcedRetryableError(ctx, redact.Sprint(err))
+		// For certain retryable errors, we should turn them into client visible
+		// errors, since the client needs to retry now.
+		var conversionError error
+		err, conversionError = ex.convertRetriableErrorIntoUserVisibleError(ctx, err)
+		if conversionError != nil {
+			return ex.makeErrEvent(conversionError, ast)
 		}
 		return ex.makeErrEvent(err, ast)
 	}

pkg/sql/conn_executor_savepoints.go

@@ -152,6 +152,12 @@ func (ex *connExecutor) execRelease(
 		// Committing the transaction failed. We'll go to state RestartWait if
 		// it's a retriable error, or to state RollbackWait otherwise.
 		if errIsRetriable(err) {
+			// For certain retryable errors, we should turn them into client visible
+			// errors, since the client needs to retry now.
+			var conversionError error
+			if err, conversionError = ex.convertRetriableErrorIntoUserVisibleError(ctx, err); conversionError != nil {
+				return ex.makeErrEvent(conversionError, s)
+			}
 			// Add the savepoint back. We want to allow a ROLLBACK TO SAVEPOINT
 			// cockroach_restart (that's the whole point of commitOnRelease).
 			env.push(*entry)