sql: rollback disallowing statements following schema change

pkg/sql/drop_test.go

@@ -495,6 +495,42 @@ func TestDropTableInterleaved(t *testing.T) {
 	}
 }
 
+func TestDropTableInTxn(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	params, _ := createTestServerParams()
+	s, sqlDB, _ := serverutils.StartServer(t, params)
+	defer s.Stopper().Stop(context.TODO())
+
+	if _, err := sqlDB.Exec(`
+CREATE DATABASE t;
+CREATE TABLE t.kv (k CHAR PRIMARY KEY, v CHAR);
+`); err != nil {
+		t.Fatal(err)
+	}
+
+	tx, err := sqlDB.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := tx.Exec(`DROP TABLE t.kv`); err != nil {
+		t.Fatal(err)
+	}
+
+	// We might still be able to read/write in the table inside this transaction
+	// until the schema changer runs, but we shouldn't be able to ALTER it.
+	if _, err := tx.Exec(`ALTER TABLE t.kv ADD COLUMN w CHAR`); !testutils.IsError(err,
+		`table "kv" is being dropped`) {
+		t.Fatalf("different error than expected: %v", err)
+	}
+
+	// Can't commit after ALTER errored, so we ROLLBACK.
+	if err := tx.Rollback(); err != nil {
+		t.Fatal(err)
+	}
+
+}
+
 func TestDropAndCreateTable(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	params, _ := createTestServerParams()

pkg/sql/executor.go

@@ -55,7 +55,6 @@ import (
 var errNoTransactionInProgress = errors.New("there is no transaction in progress")
 var errStaleMetadata = errors.New("metadata is still stale")
 var errTransactionInProgress = errors.New("there is already a transaction in progress")
-var errStmtFollowsSchemaChange = errors.New("statement cannot follow a schema change in a transaction")
 
 func errWrongNumberOfPreparedStatements(n int) error {
 	return pgerror.NewErrorf(pgerror.CodeInvalidPreparedStatementDefinitionError,
@@ -453,12 +452,6 @@ func (e *Executor) Prepare(
 		txn.Proto().OrigTimestamp = e.cfg.Clock.Now()
 	}
 
-	if len(session.TxnState.schemaChangers.schemaChangers) > 0 {
-		if _, ok := stmt.(parser.ValidAfterSchemaUpdateStatement); !ok {
-			return nil, errStmtFollowsSchemaChange
-		}
-	}
-
 	planner := session.newPlanner(e, txn)
 	planner.semaCtx.Placeholders.SetTypes(pinfo)
 	planner.evalCtx.PrepareOnly = true
@@ -672,7 +665,6 @@ func (e *Executor) execRequest(
 
 		// Track if we are retrying this query, so that we do not double count.
 		automaticRetryCount := 0
-		schemaChangerCount := len(txnState.schemaChangers.schemaChangers)
 		txnClosure := func(ctx context.Context, txn *client.Txn, opt *client.TxnExecOptions) error {
 			defer func() { automaticRetryCount++ }()
 			if txnState.State == Open && txnState.txn != txn {
@@ -681,12 +673,6 @@ func (e *Executor) execRequest(
 			}
 			txnState.txn = txn
 
-			// Remove all schema changers added by the closure.
-			if automaticRetryCount > 0 && len(txnState.schemaChangers.schemaChangers) > 0 {
-				txnState.schemaChangers.schemaChangers =
-					txnState.schemaChangers.schemaChangers[:schemaChangerCount]
-			}
-
 			if protoTS != nil {
 				SetTxnTimestamps(txnState.txn, *protoTS)
 			}
@@ -1288,12 +1274,6 @@ func (e *Executor) execStmtInOpenTxn(
 		return Result{PGTag: s.StatementTag()}, nil
 	}
 
-	if len(txnState.schemaChangers.schemaChangers) > 0 {
-		if _, ok := stmt.(parser.ValidAfterSchemaUpdateStatement); !ok {
-			return Result{}, errStmtFollowsSchemaChange
-		}
-	}
-
 	// Create a new planner from the Session to execute the statement.
 	planner := session.newPlanner(e, txnState.txn)
 	planner.evalCtx.SetTxnTimestamp(txnState.sqlTimestamp)

pkg/sql/parser/stmt.go

@@ -87,13 +87,6 @@ type IndependentFromParallelizedPriors interface {
 	independentFromParallelizedPriors()
 }
 
-// ValidAfterSchemaUpdateStatement is a pseudo-interface to be implemented by
-// statements which do not risk conflicting with an earlier schema change
-// operation issued previously within the same transaction.
-type ValidAfterSchemaUpdateStatement interface {
-	validAfterSchemaUpdateStatement()
-}
-
 // StatementType implements the Statement interface.
 func (*AlterTable) StatementType() StatementType { return DDL }
 
@@ -114,8 +107,6 @@ func (*BeginTransaction) StatementTag() string { return "BEGIN" }
 
 func (*BeginTransaction) hiddenFromStats() {}
 
-func (*BeginTransaction) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*CommitTransaction) StatementType() StatementType { return Ack }
 
@@ -124,8 +115,6 @@ func (*CommitTransaction) StatementTag() string { return "COMMIT" }
 
 func (*CommitTransaction) hiddenFromStats() {}
 
-func (*CommitTransaction) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*CopyFrom) StatementType() StatementType { return CopyIn }
 
@@ -161,8 +150,6 @@ func (*CreateUser) StatementType() StatementType { return Ack }
 // StatementTag returns a short string identifying the type of statement.
 func (*CreateUser) StatementTag() string { return "CREATE USER" }
 
-func (*CreateUser) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*CreateView) StatementType() StatementType { return DDL }
 
@@ -183,8 +170,6 @@ func (n *Deallocate) StatementTag() string {
 
 func (*Deallocate) hiddenFromStats() {}
 
-func (*Deallocate) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (n *Delete) StatementType() StatementType { return n.Returning.statementType() }
 
@@ -229,8 +214,6 @@ func (*Explain) StatementTag() string { return "EXPLAIN" }
 
 func (*Explain) hiddenFromStats() {}
 
-func (*Explain) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*Grant) StatementType() StatementType { return DDL }
 
@@ -239,8 +222,6 @@ func (*Grant) StatementTag() string { return "GRANT" }
 
 func (*Grant) hiddenFromStats() {}
 
-func (*Grant) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (n *Insert) StatementType() StatementType { return n.Returning.statementType() }
 
@@ -261,8 +242,6 @@ func (*Prepare) StatementTag() string { return "PREPARE" }
 
 func (*Prepare) hiddenFromStats() {}
 
-func (*Prepare) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*ReleaseSavepoint) StatementType() StatementType { return Ack }
 
@@ -271,8 +250,6 @@ func (*ReleaseSavepoint) StatementTag() string { return "RELEASE" }
 
 func (*ReleaseSavepoint) hiddenFromStats() {}
 
-func (*ReleaseSavepoint) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*RenameColumn) StatementType() StatementType { return DDL }
 
@@ -322,8 +299,6 @@ func (*Revoke) StatementTag() string { return "REVOKE" }
 
 func (*Revoke) hiddenFromStats() {}
 
-func (*Revoke) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*RollbackToSavepoint) StatementType() StatementType { return Ack }
 
@@ -332,8 +307,6 @@ func (*RollbackToSavepoint) StatementTag() string { return "ROLLBACK" }
 
 func (*RollbackToSavepoint) hiddenFromStats() {}
 
-func (*RollbackToSavepoint) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*RollbackTransaction) StatementType() StatementType { return Ack }
 
@@ -342,8 +315,6 @@ func (*RollbackTransaction) StatementTag() string { return "ROLLBACK" }
 
 func (*RollbackTransaction) hiddenFromStats() {}
 
-func (*RollbackTransaction) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*Savepoint) StatementType() StatementType { return Ack }
 
@@ -376,8 +347,6 @@ func (*Set) StatementTag() string { return "SET" }
 
 func (*Set) hiddenFromStats() {}
 
-func (*Set) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*SetTransaction) StatementType() StatementType { return Ack }
 
@@ -394,8 +363,6 @@ func (*SetTimeZone) StatementTag() string { return "SET TIME ZONE" }
 
 func (*SetTimeZone) hiddenFromStats() {}
 
-func (*SetTimeZone) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*SetDefaultIsolation) StatementType() StatementType { return Ack }
 
@@ -404,8 +371,6 @@ func (*SetDefaultIsolation) StatementTag() string { return "SET" }
 
 func (*SetDefaultIsolation) hiddenFromStats() {}
 
-func (*SetDefaultIsolation) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*Show) StatementType() StatementType { return Rows }
 
@@ -415,8 +380,6 @@ func (*Show) StatementTag() string { return "SHOW" }
 func (*Show) hiddenFromStats()                   {}
 func (*Show) independentFromParallelizedPriors() {}
 
-func (*Show) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*ShowColumns) StatementType() StatementType { return Rows }
 
@@ -462,8 +425,6 @@ func (*ShowGrants) StatementTag() string { return "SHOW GRANTS" }
 func (*ShowGrants) hiddenFromStats()                   {}
 func (*ShowGrants) independentFromParallelizedPriors() {}
 
-func (*ShowGrants) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*ShowIndex) StatementType() StatementType { return Rows }
 
@@ -482,8 +443,6 @@ func (*ShowTransactionStatus) StatementTag() string { return "SHOW TRANSACTION S
 func (*ShowTransactionStatus) hiddenFromStats()                   {}
 func (*ShowTransactionStatus) independentFromParallelizedPriors() {}
 
-func (*ShowTransactionStatus) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*ShowUsers) StatementType() StatementType { return Rows }
 
@@ -493,8 +452,6 @@ func (*ShowUsers) StatementTag() string { return "SHOW USERS" }
 func (*ShowUsers) hiddenFromStats()                   {}
 func (*ShowUsers) independentFromParallelizedPriors() {}
 
-func (*ShowUsers) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*ShowRanges) StatementType() StatementType { return Rows }
 
@@ -512,8 +469,6 @@ func (*Help) StatementTag() string { return "HELP" }
 func (*Help) hiddenFromStats()                   {}
 func (*Help) independentFromParallelizedPriors() {}
 
-func (*Help) validAfterSchemaUpdateStatement() {}
-
 // StatementType implements the Statement interface.
 func (*ShowConstraints) StatementType() StatementType { return Rows }
 

pkg/sql/pgwire/pgwire_test.go

@@ -450,59 +450,76 @@ func TestPGPrepareWithCreateDropInTxn(t *testing.T) {
 	}
 	defer db.Close()
 
-	tx, err := db.Begin()
-	if err != nil {
-		t.Fatal(err)
-	}
+	{
+		tx, err := db.Begin()
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if _, err := tx.Exec(`
+		if _, err := tx.Exec(`
 	CREATE DATABASE d;
 	CREATE TABLE d.kv (k CHAR PRIMARY KEY, v CHAR);
 `); err != nil {
-		t.Fatal(err)
-	}
+			t.Fatal(err)
+		}
 
-	stmt, err := tx.Prepare(`INSERT INTO d.kv (k,v) VALUES ($1, $2);`)
-	if err != nil {
-		t.Fatal(err)
-	}
+		stmt, err := tx.Prepare(`INSERT INTO d.kv (k,v) VALUES ($1, $2);`)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	res, err := stmt.Exec('a', 'b')
-	if err != nil {
-		t.Fatal(err)
-	}
-	stmt.Close()
-	affected, err := res.RowsAffected()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if affected != 1 {
-		t.Fatalf("unexpected number of rows affected: %d", affected)
-	}
+		res, err := stmt.Exec('a', 'b')
+		if err != nil {
+			t.Fatal(err)
+		}
+		stmt.Close()
+		affected, err := res.RowsAffected()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if affected != 1 {
+			t.Fatalf("unexpected number of rows affected: %d", affected)
+		}
 
-	if err := tx.Commit(); err != nil {
-		t.Fatal(err)
+		if err := tx.Commit(); err != nil {
+			t.Fatal(err)
+		}
 	}
 
-	tx, err = db.Begin()
-	if err != nil {
-		t.Fatal(err)
-	}
+	{
+		tx, err := db.Begin()
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if _, err := tx.Exec(`
+		if _, err := tx.Exec(`
 	DROP TABLE d.kv;
 `); err != nil {
-		t.Fatal(err)
-	}
+			t.Fatal(err)
+		}
 
-	if _, err := tx.Prepare(`
-	INSERT INTO d.kv (k,v) VALUES ($1, $2);
-`); !testutils.IsError(err, "statement cannot follow a schema change in a transaction") {
-		t.Fatalf("got err: %s", err)
-	}
+		stmt, err := tx.Prepare(`INSERT INTO d.kv (k,v) VALUES ($1, $2);`)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if err := tx.Rollback(); err != nil {
-		t.Fatal(err)
+		// INSERT works because it is using a cached descriptor that is leased.
+		res, err := stmt.Exec('c', 'd')
+		if err != nil {
+			t.Fatal(err)
+		}
+		stmt.Close()
+		affected, err := res.RowsAffected()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if affected != 1 {
+			t.Fatalf("unexpected number of rows affected: %d", affected)
+		}
+
+		if err := tx.Commit(); err != nil {
+			t.Fatal(err)
+		}
 	}
 }