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Accept transaction isolation levels, but always use REPEATABLE READ #3063

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Merged
fulghum merged 3 commits into from
Aug 11, 2026
Merged

Accept transaction isolation levels, but always use REPEATABLE READ #3063

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c6544b4
Accept transaction isolation levels, but always default to REPEATABLE…
fulghum Aug 10, 2026
51f9d06
Bug fix for an issue with nested BEGINs (found by ItoQA)
fulghum Aug 10, 2026
49d5cc9
Bug fix for ROLLBACK not marking that the session is not currently in…
fulghum Aug 10, 2026
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8 changes: 4 additions & 4 deletions postgres/parser/parser/sql.go
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8 changes: 4 additions & 4 deletions postgres/parser/parser/sql.y
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Original file line number Diff line number Diff line change
Expand Up @@ -6295,19 +6295,19 @@ extra_var_value:
iso_level:
READ UNCOMMITTED
{
$$.val = tree.SerializableIsolation
$$.val = tree.ReadUncommittedIsolation
}
| READ COMMITTED
{
$$.val = tree.SerializableIsolation
$$.val = tree.ReadCommittedIsolation
}
| SNAPSHOT
{
$$.val = tree.SerializableIsolation
$$.val = tree.SnapshotIsolation
}
| REPEATABLE READ
{
$$.val = tree.SerializableIsolation
$$.val = tree.RepeatableReadIsolation
}
| SERIALIZABLE
{
Expand Down
18 changes: 15 additions & 3 deletions postgres/parser/sem/tree/txn.go
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Expand Up @@ -38,18 +38,30 @@ type IsolationLevel int
// IsolationLevel values
const (
UnspecifiedIsolation IsolationLevel = iota
ReadUncommittedIsolation
ReadCommittedIsolation
RepeatableReadIsolation
SerializableIsolation
SnapshotIsolation
)

var isolationLevelNames = [...]string{
UnspecifiedIsolation: "UNSPECIFIED",
SerializableIsolation: "SERIALIZABLE",
UnspecifiedIsolation: "UNSPECIFIED",
ReadUncommittedIsolation: "READ UNCOMMITTED",
ReadCommittedIsolation: "READ COMMITTED",
RepeatableReadIsolation: "REPEATABLE READ",
SerializableIsolation: "SERIALIZABLE",
SnapshotIsolation: "SNAPSHOT",
}

// IsolationLevelMap is a map from string isolation level name to isolation
// level, in the lowercase format that set isolation_level supports.
var IsolationLevelMap = map[string]IsolationLevel{
"serializable": SerializableIsolation,
"read uncommitted": ReadUncommittedIsolation,
"read committed": ReadCommittedIsolation,
"repeatable read": RepeatableReadIsolation,
"serializable": SerializableIsolation,
"snapshot": SnapshotIsolation,
}

func (i IsolationLevel) String() string {
Expand Down
9 changes: 6 additions & 3 deletions server/ast/begin_transaction.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,9 +27,12 @@ func nodeBeginTransaction(ctx *Context, node *tree.BeginTransaction) (*vitess.Be
if node == nil {
return nil, nil
}
if node.Modes.Isolation != tree.UnspecifiedIsolation {
return nil, errors.Errorf("isolation levels are not yet supported")
}

// TODO: When Dolt supports additional transaction isolation levels, we can plug them
Comment thread
fulghum marked this conversation as resolved.
// in here based on what the user has set in node.Modes.Isolation
// For now, we follow Dolt's lead and support the syntax for isolation levels, but
// always use REPEATABLE READ semantics.

if node.Modes.UserPriority != tree.UnspecifiedUserPriority {
return nil, errors.Errorf("user priority is not yet supported")
}
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13 changes: 12 additions & 1 deletion server/connection_handler.go
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Expand Up @@ -66,7 +66,7 @@ type ConnectionHandler struct {
// copyFromStdinState is set when this connection is in the COPY FROM STDIN mode, meaning it is waiting on
// COPY DATA messages from the client to import data into tables.
copyFromStdinState *copyFromStdinState
// inTransaction is set to true with BEGIN query and false with COMMIT query.
// inTransaction is set to true with BEGIN query and false with COMMIT or ROLLBACK query.
inTransaction bool
}

Expand Down Expand Up @@ -513,9 +513,20 @@ func (h *ConnectionHandler) handleQuery(message *pgproto3.Query) (endOfMessages
func (h *ConnectionHandler) handleQueryOutsideEngine(query ConvertedQuery) (handled bool, endOfMessages bool, err error) {
Comment thread
fulghum marked this conversation as resolved.
switch stmt := query.AST.(type) {
case *sqlparser.Begin:
if h.inTransaction {
// Postgres treats a BEGIN issued while already inside a transaction block as a no-op
// (after emitting a warning): the existing transaction, and its original characteristics
// (isolation level, read/write mode), continue unchanged. If we forwarded this statement
// to the engine instead, it would start a brand new transaction using this statement's
// characteristics, silently discarding the active one (e.g. a READ WRITE transaction could
// be replaced by a READ ONLY one, causing writes to be rejected and changes to be lost).
return true, true, h.send(makeCommandComplete(query.StatementTag, 0))
}
h.inTransaction = true
case *sqlparser.Commit:
h.inTransaction = false
case *sqlparser.Rollback:
h.inTransaction = false
case *sqlparser.Deallocate:
return true, true, h.deallocatePreparedStatement(stmt.Name, h.preparedStatements, query, h.Conn())
case sqlparser.InjectedStatement:
Expand Down
120 changes: 60 additions & 60 deletions testing/generation/command_docs/output/begin_test.go
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Expand Up @@ -21,18 +21,18 @@ func TestBegin(t *testing.T) {
Converts("BEGIN"),
Converts("BEGIN WORK"),
Converts("BEGIN TRANSACTION"),
Parses("BEGIN ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN WORK ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN WORK ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN WORK ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN WORK ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN WORK ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN WORK ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN READ WRITE"),
Converts("BEGIN WORK READ WRITE"),
Converts("BEGIN TRANSACTION READ WRITE"),
Expand All @@ -57,12 +57,12 @@ func TestBegin(t *testing.T) {
Unimplemented("BEGIN ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL SERIALIZABLE"),
Unimplemented("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL SERIALIZABLE"),
Unimplemented("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN READ WRITE , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN WORK READ WRITE , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN READ ONLY , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN WORK READ ONLY , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN READ WRITE , ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN WORK READ WRITE , ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN READ ONLY , ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN WORK READ ONLY , ISOLATION LEVEL SERIALIZABLE"),
Converts("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN DEFERRABLE , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN WORK DEFERRABLE , ISOLATION LEVEL SERIALIZABLE"),
Parses("BEGIN TRANSACTION DEFERRABLE , ISOLATION LEVEL SERIALIZABLE"),
Expand All @@ -81,12 +81,12 @@ func TestBegin(t *testing.T) {
Unimplemented("BEGIN ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL REPEATABLE READ"),
Unimplemented("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL REPEATABLE READ"),
Unimplemented("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN READ WRITE , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN WORK READ WRITE , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN READ ONLY , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN WORK READ ONLY , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN READ WRITE , ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN WORK READ WRITE , ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN READ ONLY , ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN WORK READ ONLY , ISOLATION LEVEL REPEATABLE READ"),
Converts("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN DEFERRABLE , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN WORK DEFERRABLE , ISOLATION LEVEL REPEATABLE READ"),
Parses("BEGIN TRANSACTION DEFERRABLE , ISOLATION LEVEL REPEATABLE READ"),
Expand All @@ -105,12 +105,12 @@ func TestBegin(t *testing.T) {
Unimplemented("BEGIN ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL READ COMMITTED"),
Unimplemented("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL READ COMMITTED"),
Unimplemented("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN READ WRITE , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN WORK READ WRITE , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN READ ONLY , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN WORK READ ONLY , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN READ WRITE , ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN WORK READ WRITE , ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN READ ONLY , ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN WORK READ ONLY , ISOLATION LEVEL READ COMMITTED"),
Converts("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN DEFERRABLE , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN WORK DEFERRABLE , ISOLATION LEVEL READ COMMITTED"),
Parses("BEGIN TRANSACTION DEFERRABLE , ISOLATION LEVEL READ COMMITTED"),
Expand All @@ -129,30 +129,30 @@ func TestBegin(t *testing.T) {
Unimplemented("BEGIN ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL READ UNCOMMITTED"),
Unimplemented("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL READ UNCOMMITTED"),
Unimplemented("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN READ WRITE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN WORK READ WRITE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN READ ONLY , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN WORK READ ONLY , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN READ WRITE , ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN WORK READ WRITE , ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN TRANSACTION READ WRITE , ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN READ ONLY , ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN WORK READ ONLY , ISOLATION LEVEL READ UNCOMMITTED"),
Converts("BEGIN TRANSACTION READ ONLY , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN DEFERRABLE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN WORK DEFERRABLE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN TRANSACTION DEFERRABLE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN NOT DEFERRABLE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN WORK NOT DEFERRABLE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN TRANSACTION NOT DEFERRABLE , ISOLATION LEVEL READ UNCOMMITTED"),
Parses("BEGIN ISOLATION LEVEL SERIALIZABLE , READ WRITE"),
Parses("BEGIN WORK ISOLATION LEVEL SERIALIZABLE , READ WRITE"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE , READ WRITE"),
Parses("BEGIN ISOLATION LEVEL REPEATABLE READ , READ WRITE"),
Parses("BEGIN WORK ISOLATION LEVEL REPEATABLE READ , READ WRITE"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ , READ WRITE"),
Parses("BEGIN ISOLATION LEVEL READ COMMITTED , READ WRITE"),
Parses("BEGIN WORK ISOLATION LEVEL READ COMMITTED , READ WRITE"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED , READ WRITE"),
Parses("BEGIN ISOLATION LEVEL READ UNCOMMITTED , READ WRITE"),
Parses("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , READ WRITE"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , READ WRITE"),
Converts("BEGIN ISOLATION LEVEL SERIALIZABLE , READ WRITE"),
Converts("BEGIN WORK ISOLATION LEVEL SERIALIZABLE , READ WRITE"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE , READ WRITE"),
Converts("BEGIN ISOLATION LEVEL REPEATABLE READ , READ WRITE"),
Converts("BEGIN WORK ISOLATION LEVEL REPEATABLE READ , READ WRITE"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ , READ WRITE"),
Converts("BEGIN ISOLATION LEVEL READ COMMITTED , READ WRITE"),
Converts("BEGIN WORK ISOLATION LEVEL READ COMMITTED , READ WRITE"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED , READ WRITE"),
Converts("BEGIN ISOLATION LEVEL READ UNCOMMITTED , READ WRITE"),
Converts("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , READ WRITE"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , READ WRITE"),
Unimplemented("BEGIN READ WRITE , READ WRITE"),
Unimplemented("BEGIN WORK READ WRITE , READ WRITE"),
Unimplemented("BEGIN TRANSACTION READ WRITE , READ WRITE"),
Expand All @@ -165,18 +165,18 @@ func TestBegin(t *testing.T) {
Parses("BEGIN NOT DEFERRABLE , READ WRITE"),
Parses("BEGIN WORK NOT DEFERRABLE , READ WRITE"),
Parses("BEGIN TRANSACTION NOT DEFERRABLE , READ WRITE"),
Parses("BEGIN ISOLATION LEVEL SERIALIZABLE , READ ONLY"),
Parses("BEGIN WORK ISOLATION LEVEL SERIALIZABLE , READ ONLY"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE , READ ONLY"),
Parses("BEGIN ISOLATION LEVEL REPEATABLE READ , READ ONLY"),
Parses("BEGIN WORK ISOLATION LEVEL REPEATABLE READ , READ ONLY"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ , READ ONLY"),
Parses("BEGIN ISOLATION LEVEL READ COMMITTED , READ ONLY"),
Parses("BEGIN WORK ISOLATION LEVEL READ COMMITTED , READ ONLY"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED , READ ONLY"),
Parses("BEGIN ISOLATION LEVEL READ UNCOMMITTED , READ ONLY"),
Parses("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , READ ONLY"),
Parses("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , READ ONLY"),
Converts("BEGIN ISOLATION LEVEL SERIALIZABLE , READ ONLY"),
Converts("BEGIN WORK ISOLATION LEVEL SERIALIZABLE , READ ONLY"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE , READ ONLY"),
Converts("BEGIN ISOLATION LEVEL REPEATABLE READ , READ ONLY"),
Converts("BEGIN WORK ISOLATION LEVEL REPEATABLE READ , READ ONLY"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ , READ ONLY"),
Converts("BEGIN ISOLATION LEVEL READ COMMITTED , READ ONLY"),
Converts("BEGIN WORK ISOLATION LEVEL READ COMMITTED , READ ONLY"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL READ COMMITTED , READ ONLY"),
Converts("BEGIN ISOLATION LEVEL READ UNCOMMITTED , READ ONLY"),
Converts("BEGIN WORK ISOLATION LEVEL READ UNCOMMITTED , READ ONLY"),
Converts("BEGIN TRANSACTION ISOLATION LEVEL READ UNCOMMITTED , READ ONLY"),
Unimplemented("BEGIN READ WRITE , READ ONLY"),
Unimplemented("BEGIN WORK READ WRITE , READ ONLY"),
Unimplemented("BEGIN TRANSACTION READ WRITE , READ ONLY"),
Expand Down
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