From e934fa6a6eff4f427c9a5ab663d6e2e77486aaa0 Mon Sep 17 00:00:00 2001
From: Martin Gallwey <mgy5@3ds.com>
Date: Mon, 29 Jun 2026 18:12:27 +0100
Subject: [PATCH] Optimize result fetching via block-draining and check
 inlining

Accelerate data retrieval pathways in the Cursor class by optimizing row
iteration and reducing interpreter overhead on high-frequency method loops.

Detailed changes:
- fetchone: Inline the `_check_closed()` state verification directly into the
  method body. This removes function-call stack overhead for every individual
  row retrieved.
- fetchall: Refactor the loop to slice and drain the current in-memory result
  batch in bulk using `list.extend()` instead of sequentially invoking
  `fetchone()` row by row.
- fetchall: Directly request the next network payload batch via
  `fetch_result_set_next` once the in-memory collection is exhausted, updating
  total `rownumber` tracking as a single block operation.
- fetchall: Add a defensive guard clause against unallocated result sets to
  ensure strict DB-API compatibility.
---
 pynuodb/cursor.py | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/pynuodb/cursor.py b/pynuodb/cursor.py
index 4e515f5..f944518 100644
--- a/pynuodb/cursor.py
+++ b/pynuodb/cursor.py
@@ -184,7 +184,11 @@ def executemany(self, operation, seq_of_parameters):
     def fetchone(self):
         # type: () -> Optional[result_set.Row]
         """Return the next row of results from the previous SQL operation."""
-        self._check_closed()
+        # Inline _check_closed to avoid per-row function-call overhead.
+        if self.closed:
+            raise Error("cursor is closed")
+        if self.session.closed:
+            raise Error("connection is closed")
         if self._result_set is None:
             raise Error("Previous execute did not produce any results or no call was issued yet")
         self.rownumber += 1
@@ -218,14 +222,22 @@ def fetchall(self):
         # type: () -> List[result_set.Row]
         """Return all rows generated by the previous SQL operation."""
         self._check_closed()
+        if self._result_set is None:
+            raise Error("Previous execute did not produce any results or no call was issued yet")
 
-        fetched_rows = []
+        fetched_rows = []  # type: List[result_set.Row]
         while True:
-            row = self.fetchone()
-            if row is None:
+            # Drain the current in-memory batch in one shot instead of calling
+            # fetchone() per row.
+            idx = self._result_set.results_idx
+            batch = self._result_set.results
+            if idx < len(batch):
+                fetched_rows.extend(batch[idx:])
+                self._result_set.results_idx = len(batch)
+            if self._result_set.complete:
                 break
-            else:
-                fetched_rows.append(row)
+            self.session.fetch_result_set_next(self._result_set)
+        self.rownumber += len(fetched_rows)
         return fetched_rows
 
     def nextset(self):  # pylint: disable=no-self-use