From e13cc9954392521ec4c9d0d01a96e3f3a1ecaa40 Mon Sep 17 00:00:00 2001
From: Peter Adams <18162810+Maxteabag@users.noreply.github.com>
Date: Wed, 5 Aug 2026 19:32:07 +0200
Subject: [PATCH] fix(oracle): cap fetch buffers to result limit

---
 .../connections/providers/oracle/adapter.py   |  7 +++---
 .../oracle/test_statement_execution.py        | 24 +++++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/sqlit/domains/connections/providers/oracle/adapter.py b/sqlit/domains/connections/providers/oracle/adapter.py
index d295a1ec..92e00232 100644
--- a/sqlit/domains/connections/providers/oracle/adapter.py
+++ b/sqlit/domains/connections/providers/oracle/adapter.py
@@ -384,9 +384,10 @@ def execute_query(self, conn: Any, query: str, max_rows: int | None = None) -> t
         cursor = conn.cursor()
         try:
             # Larger fetch batches cut per-round-trip overhead on high-latency
-            # links (oracledb defaults: arraysize=100, prefetchrows=2).
-            cursor.arraysize = 1000
-            cursor.prefetchrows = 1001
+            # links without fetching beyond the requested result cap.
+            row_budget = max_rows + 1 if max_rows is not None else 1001
+            cursor.arraysize = min(1000, max(1, row_budget))
+            cursor.prefetchrows = min(1001, max(1, row_budget))
             cursor.execute(_prepare_statement(query))
             if cursor.description:
                 columns = [col[0] for col in cursor.description]
diff --git a/tests/connections/providers/oracle/test_statement_execution.py b/tests/connections/providers/oracle/test_statement_execution.py
index 73eda739..1b8a886e 100644
--- a/tests/connections/providers/oracle/test_statement_execution.py
+++ b/tests/connections/providers/oracle/test_statement_execution.py
@@ -43,6 +43,30 @@ def test_execute_query_removes_sql_statement_terminator(
     mock_conn.cursor.return_value.execute.assert_called_once_with(expected)
 
 
+@pytest.mark.parametrize(
+    ("max_rows", "expected_arraysize", "expected_prefetchrows"),
+    [
+        (None, 1000, 1001),
+        (1, 2, 2),
+        (999, 1000, 1000),
+        (1000, 1000, 1001),
+    ],
+)
+def test_execute_query_caps_fetch_buffers_to_requested_rows(
+    adapter: OracleAdapter,
+    mock_conn: MagicMock,
+    max_rows: int | None,
+    expected_arraysize: int,
+    expected_prefetchrows: int,
+) -> None:
+    """Small result limits must not prefetch hundreds of discarded rows."""
+    adapter.execute_query(mock_conn, "SELECT 1 FROM DUAL", max_rows=max_rows)
+
+    cursor = mock_conn.cursor.return_value
+    assert cursor.arraysize == expected_arraysize
+    assert cursor.prefetchrows == expected_prefetchrows
+
+
 def test_execute_non_query_removes_sql_statement_terminator(
     adapter: OracleAdapter,
     mock_conn: MagicMock,