add an option deferred_fetch to Cursor.execute()

Author: dungdm93

tests/unit/test_client.py

@@ -1018,6 +1018,57 @@ def json(self):
         assert isinstance(result, TrinoResult)
 
 
+def test_trino_query_deferred_fetch(sample_get_response_data):
+    """
+    Validates that the `TrinoQuery.execute` function deferred_fetch and non-block execution
+    """
+
+    class MockResponse(mock.Mock):
+        # Fake response class
+        @property
+        def headers(self):
+            return {
+                'X-Trino-Fake-1': 'one',
+                'X-Trino-Fake-2': 'two',
+            }
+
+        def json(self):
+            return sample_get_response_data
+
+    rows = sample_get_response_data['data']
+    sample_get_response_data['data'] = []
+    sql = 'SELECT 1'
+    request = TrinoRequest(
+        host="coordinator",
+        port=8080,
+        client_session=ClientSession(
+            user="test",
+            source="test",
+            catalog="test",
+            schema="test",
+            properties={},
+        ),
+        http_scheme="http",
+    )
+    query = TrinoQuery(
+        request=request,
+        query=sql
+    )
+
+    with \
+            mock.patch.object(request, 'post', return_value=MockResponse()), \
+            mock.patch.object(query, 'fetch', return_value=rows) as mock_fetch:
+        result = query.execute()
+        mock_fetch.assert_called_once()
+        assert result.rows == rows
+
+    with \
+            mock.patch.object(request, 'post', return_value=MockResponse()), \
+            mock.patch.object(query, 'fetch', return_value=rows) as mock_fetch:
+        result = query.execute(deferred_fetch=True)
+        mock_fetch.assert_not_called()
+
+
 def test_delay_exponential_without_jitter():
     max_delay = 1200.0
     get_delay = _DelayExponential(base=5, jitter=False, max_delay=max_delay)

trino/client.py

@@ -777,13 +777,18 @@ def result(self):
     def info_uri(self):
         return self._info_uri
 
-    def execute(self, additional_http_headers=None) -> TrinoResult:
-        """Initiate a Trino query by sending the SQL statement
-
-        This is the first HTTP request sent to the coordinator.
-        It sets the query_id and returns a Result object used to
-        track the rows returned by the query. To fetch all rows,
-        call fetch() until finished is true.
+    def execute(
+        self,
+        additional_http_headers: Optional[Dict[str, Any]] = None,
+        deferred_fetch: bool = False,
+    ) -> TrinoResult:
+        """Initiate a Trino query by sending the SQL statement to the coordinator.
+        To fetch all rows, call fetch() until finished is true.
+
+        Parameters:
+            additional_http_headers: extra headers send to the Trino server.
+            deferred_fetch: By default, the execution is blocked until at least one row is received
+                or query is finished or cancelled. To continue without waiting the result, set deferred_fetch=True.
         """
         if self.cancelled:
             raise exceptions.TrinoUserError("Query has been cancelled", self.query_id)
@@ -804,9 +809,11 @@ def execute(self, additional_http_headers=None) -> TrinoResult:
         rows = self._row_mapper.map(status.rows) if self._row_mapper else status.rows
         self._result = TrinoResult(self, rows)
 
-        # Execute should block until at least one row is received or query is finished or cancelled
-        while not self.finished and not self.cancelled and len(self._result.rows) == 0:
-            self._result.rows += self.fetch()
+        if not deferred_fetch:
+            # Execute should block until at least one row is received or query is finished or cancelled
+            while not self.finished and not self.cancelled and len(self._result.rows) == 0:
+                self._result.rows += self.fetch()
+
         return self._result
 
     def _update_state(self, status):

trino/dbapi.py

@@ -558,7 +558,10 @@ def _deallocate_prepared_statement(self, statement_name: str) -> None:
     def _generate_unique_statement_name(self):
         return 'st_' + uuid.uuid4().hex.replace('-', '')
 
-    def execute(self, operation, params=None):
+    def execute(self, operation, params=None, **kwargs: Any):
+        additional_http_headers = kwargs.get("additional_http_headers", None)
+        deferred_fetch = kwargs.get("deferred_fetch", False)
+
         if params:
             assert isinstance(params, (list, tuple)), (
                 'params must be a list or tuple containing the query '
@@ -575,7 +578,10 @@ def execute(self, operation, params=None):
                     self._query = self._execute_prepared_statement(
                         statement_name, params
                     )
-                    self._iterator = iter(self._query.execute())
+                    self._iterator = iter(self._query.execute(
+                        additional_http_headers=additional_http_headers,
+                        deferred_fetch=deferred_fetch,
+                    ))
                 finally:
                     # Send deallocate statement
                     # At this point the query can be deallocated since it has already
@@ -584,12 +590,18 @@ def execute(self, operation, params=None):
                     self._deallocate_prepared_statement(statement_name)
             else:
                 self._query = self._execute_immediate_statement(operation, params)
-                self._iterator = iter(self._query.execute())
+                self._iterator = iter(self._query.execute(
+                    additional_http_headers=additional_http_headers,
+                    deferred_fetch=deferred_fetch,
+                ))
 
         else:
             self._query = trino.client.TrinoQuery(self._request, query=operation,
                                                   legacy_primitive_types=self._legacy_primitive_types)
-            self._iterator = iter(self._query.execute())
+            self._iterator = iter(self._query.execute(
+                additional_http_headers=additional_http_headers,
+                deferred_fetch=deferred_fetch,
+            ))
         return self
 
     def executemany(self, operation, seq_of_params):

trino/sqlalchemy/dialect.py

@@ -396,7 +396,7 @@ def _get_default_schema_name(self, connection: Connection) -> Optional[str]:
     def do_execute(
         self, cursor: Cursor, statement: str, parameters: Tuple[Any, ...], context: DefaultExecutionContext = None
     ):
-        cursor.execute(statement, parameters)
+        cursor.execute(statement, parameters, **context.execution_options)
 
     def do_rollback(self, dbapi_connection: trino_dbapi.Connection):
         if dbapi_connection.transaction is not None: