Implement snapshot isolation mode support in query client

tests/aio/query/test_query_session_pool.py

@@ -69,6 +69,7 @@ async def callee(session: QuerySession):
             (None),
             (ydb.QuerySerializableReadWrite()),
             (ydb.QuerySnapshotReadOnly()),
+            (ydb.QuerySnapshotReadWrite()),
             (ydb.QueryOnlineReadOnly()),
             (ydb.QueryStaleReadOnly()),
         ],

tests/query/test_query_session_pool.py

@@ -68,6 +68,7 @@ def callee(session: QuerySession):
             (None),
             (ydb.QuerySerializableReadWrite()),
             (ydb.QuerySnapshotReadOnly()),
+            (ydb.QuerySnapshotReadWrite()),
             (ydb.QueryOnlineReadOnly()),
             (ydb.QueryStaleReadOnly()),
         ],

ydb/_grpc/grpcwrapper/ydb_query.py

@@ -79,6 +79,9 @@ def to_proto(self) -> ydb_query_pb2.TransactionSettings:
             return ydb_query_pb2.TransactionSettings(online_read_only=self.tx_mode.to_proto())
         if self.tx_mode.name == "stale_read_only":
             return ydb_query_pb2.TransactionSettings(stale_read_only=self.tx_mode.to_proto())
+        if self.tx_mode.name == "snapshot_read_write":
+            return ydb_query_pb2.TransactionSettings(snapshot_read_write=self.tx_mode.to_proto())
+        raise ValueError(f"Unknown transaction mode: {self.tx_mode.name}")
 
 
 @dataclass

ydb/_grpc/grpcwrapper/ydb_query_public_types.py

@@ -93,3 +93,21 @@ def name(self):
 
     def to_proto(self) -> ydb_query_pb2.StaleModeSettings:
         return ydb_query_pb2.StaleModeSettings()
+
+
+class QuerySnapshotReadWrite(BaseQueryTxMode):
+    """Snapshot isolation mode with read-write support.
+    All read operations within a transaction access the database snapshot.
+    The snapshot is taken when the transaction begins.
+    Write operations are also allowed in this mode.
+    """
+
+    def __init__(self):
+        self._name = "snapshot_read_write"
+
+    @property
+    def name(self) -> str:
+        return self._name
+
+    def to_proto(self) -> ydb_query_pb2.SnapshotRWModeSettings:
+        return ydb_query_pb2.SnapshotRWModeSettings()