Warn only once about unknown zoneinfo

diff --git a/psycopg3/psycopg3/connection.py b/psycopg3/psycopg3/connection.py
index 7ba7595dae78ca4d67bd82030f2ecf6082f7df2d..c4bd0a9c2afd3894c9bc7d9af72afa59b64d9055 100644 (file)
--- a/psycopg3/psycopg3/connection.py
+++ b/psycopg3/psycopg3/connection.py
@@ -9,7 +9,7 @@ import logging
 import warnings
 import threading
 from types import TracebackType
-from typing import Any, AsyncIterator, Callable, Generic, Iterator, List
+from typing import Any, AsyncIterator, Dict, Callable, Generic, Iterator, List
 from typing import NamedTuple, Optional, Type, TypeVar, Union
 from typing import overload, TYPE_CHECKING
 from weakref import ref, ReferenceType
@@ -59,7 +59,7 @@ else:
     connect = generators.connect
     execute = generators.execute
 
-_UTC = ZoneInfo("UTC")
+_timezones: Dict[Union[None, bytes], ZoneInfo] = {}
 
 
 class Notify(NamedTuple):
@@ -225,17 +225,20 @@ class BaseConnection(AdaptContext, Generic[Row]):
     def timezone(self) -> ZoneInfo:
         """The Python timezone info of the connection's timezone."""
         tzname = self.pgconn.parameter_status(b"TimeZone")
-        if tzname:
+        try:
+            return _timezones[tzname]
+        except KeyError:
+            sname = tzname.decode("utf8") if tzname else "UTC"
             try:
-                return ZoneInfo(tzname.decode("utf8"))
+                zi = ZoneInfo(sname)
             except KeyError:
                 logger.warning(
-                    "unknown PostgreSQL timezone: %r will use UTC",
-                    tzname.decode("utf8"),
+                    "unknown PostgreSQL timezone: %r will use UTC", sname
                 )
-                return _UTC
-        else:
-            return _UTC
+                zi = ZoneInfo("UTC")
+
+            _timezones[tzname] = zi
+            return zi
 
     @property
     def info(self) -> ConnectionInfo:

diff --git a/psycopg3/psycopg3/types/date.py b/psycopg3/psycopg3/types/date.py
index 892a14227a799a426b1fa0904755f80981d4f806..844a8bef909e375276d828dde2c2fab9836d39fd 100644 (file)
--- a/psycopg3/psycopg3/types/date.py
+++ b/psycopg3/psycopg3/types/date.py
@@ -41,8 +41,6 @@ _pg_datetime_epoch = datetime(2000, 1, 1)
 _pg_datetimetz_epoch = datetime(2000, 1, 1, tzinfo=timezone.utc)
 _py_date_min_days = date.min.toordinal()
 
-_UTC = ZoneInfo("UTC")
-
 
 class DateDumper(Dumper):
 
@@ -522,7 +520,9 @@ class TimestampTzLoader(TimestampLoader):
 
     def __init__(self, oid: int, context: Optional[AdaptContext] = None):
         super().__init__(oid, context)
-        self._timezone = self.connection.timezone if self.connection else _UTC
+        self._timezone = (
+            self.connection.timezone if self.connection else ZoneInfo("UTC")
+        )
 
     def _format_from_context(self) -> str:
         ds = self._get_datestyle()
@@ -607,7 +607,9 @@ class TimestampTzBinaryLoader(Loader):
 
     def __init__(self, oid: int, context: Optional[AdaptContext] = None):
         super().__init__(oid, context)
-        self._timezone = self.connection.timezone if self.connection else _UTC
+        self._timezone = (
+            self.connection.timezone if self.connection else ZoneInfo("UTC")
+        )
 
     def load(self, data: Buffer) -> datetime:
         micros = _unpack_int8(data)[0]