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PERF: Optimize fetch API performance #558

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PERF: Optimize fetch API performance with cached encodings, skip diag…
jahnvi480 May 7, 2026
5b91325
Applying python linting changes
jahnvi480 May 7, 2026
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Applying python linting changes
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@jahnvi480
jahnvi480 committed May 7, 2026
commit 5b91325f24c2a88aa00b21cf9e97055dc5aff976
14 changes: 5 additions & 9 deletions mssql_python/cursor.py
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Original file line number Diff line number Diff line change
Expand Up @@ -160,9 +160,9 @@ def __init__(self, connection: "Connection", timeout: int = 0) -> None:
self._has_result_set = False # Track if we have an active result set
# Cache decoding encoding strings — these don't change between fetches,
# so we avoid 2 method calls + 2 dict.get() per fetch call.
self._cached_char_encoding = self._get_decoding_settings(
ddbc_sql_const.SQL_CHAR.value
).get("encoding", "utf-8")
self._cached_char_encoding = self._get_decoding_settings(ddbc_sql_const.SQL_CHAR.value).get(
"encoding", "utf-8"
)
self._cached_wchar_encoding = self._get_decoding_settings(
ddbc_sql_const.SQL_WCHAR.value
).get("encoding", "utf-16le")
Expand Down Expand Up @@ -2569,9 +2569,7 @@ def fetchmany(self, size: Optional[int] = None) -> List[Row]:
uuid_idx = self._uuid_str_indices
# Fast path: build Row objects in C++ — avoids Python loop overhead
if not converter_map and not uuid_idx:
return ddbc_bindings.construct_rows(
rows_data, Row, column_map, self
)
return ddbc_bindings.construct_rows(rows_data, Row, column_map, self)
return [
Row(
row_data,
Expand Down Expand Up @@ -2635,9 +2633,7 @@ def fetchall(self) -> List[Row]:
uuid_idx = self._uuid_str_indices
# Fast path: build Row objects in C++ — avoids Python loop overhead
if not converter_map and not uuid_idx:
return ddbc_bindings.construct_rows(
rows_data, Row, column_map, self
)
return ddbc_bindings.construct_rows(rows_data, Row, column_map, self)
return [
Row(
row_data,
Expand Down
2 changes: 1 addition & 1 deletion mssql_python/row.py
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Expand Up @@ -29,7 +29,7 @@ class Row:

# __slots__ eliminates per-instance __dict__ (~232 bytes/row savings),
# and makes attribute access ~30% faster (array index vs dict lookup).
__slots__ = ('_values', '_column_map', '_cursor')
__slots__ = ("_values", "_column_map", "_cursor")

@staticmethod
def _fast_create(values, column_map, cursor):
Expand Down
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