Fixed #30899 -- Lazily compiled import time regular expressions.

django/db/backends/mysql/base.py

@@ -3,14 +3,13 @@ MySQL database backend for Django.
 
 Requires mysqlclient: https://pypi.org/project/mysqlclient/
 """
-import re
-
 from django.core.exceptions import ImproperlyConfigured
 from django.db import utils
 from django.db.backends import utils as backend_utils
 from django.db.backends.base.base import BaseDatabaseWrapper
 from django.utils.asyncio import async_unsafe
 from django.utils.functional import cached_property
+from django.utils.regex_helper import _lazy_re_compile
 
 try:
     import MySQLdb as Database
@@ -47,7 +46,7 @@ django_conversions = {
 
 # This should match the numerical portion of the version numbers (we can treat
 # versions like 5.0.24 and 5.0.24a as the same).
-server_version_re = re.compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
+server_version_re = _lazy_re_compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
 
 
 class CursorWrapper:

django/db/backends/oracle/operations.py

@@ -1,5 +1,4 @@
 import datetime
-import re
 import uuid
 from functools import lru_cache
 
@@ -12,6 +11,7 @@ from django.db.utils import DatabaseError
 from django.utils import timezone
 from django.utils.encoding import force_bytes, force_str
 from django.utils.functional import cached_property
+from django.utils.regex_helper import _lazy_re_compile
 
 from .base import Database
 from .utils import BulkInsertMapper, InsertVar, Oracle_datetime
@@ -102,7 +102,7 @@ END;
     # if the time zone name is passed in parameter. Use interpolation instead.
     # https://groups.google.com/forum/#!msg/django-developers/zwQju7hbG78/9l934yelwfsJ
     # This regexp matches all time zone names from the zoneinfo database.
-    _tzname_re = re.compile(r'^[\w/:+-]+$')
+    _tzname_re = _lazy_re_compile(r'^[\w/:+-]+$')
 
     def _prepare_tzname_delta(self, tzname):
         if '+' in tzname:

django/db/backends/sqlite3/base.py

@@ -23,6 +23,7 @@ from django.utils import timezone
 from django.utils.asyncio import async_unsafe
 from django.utils.dateparse import parse_datetime, parse_time
 from django.utils.duration import duration_microseconds
+from django.utils.regex_helper import _lazy_re_compile
 
 from .client import DatabaseClient                          # isort:skip
 from .creation import DatabaseCreation                      # isort:skip
@@ -380,7 +381,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         return self.creation.is_in_memory_db(self.settings_dict['NAME'])
 
 
-FORMAT_QMARK_REGEX = re.compile(r'(?<!%)%s')
+FORMAT_QMARK_REGEX = _lazy_re_compile(r'(?<!%)%s')
 
 
 class SQLiteCursorWrapper(Database.Cursor):

django/db/backends/sqlite3/introspection.py

@@ -7,10 +7,11 @@ from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo as BaseFieldInfo, TableInfo,
 )
 from django.db.models.indexes import Index
+from django.utils.regex_helper import _lazy_re_compile
 
 FieldInfo = namedtuple('FieldInfo', BaseFieldInfo._fields + ('pk',))
 
-field_size_re = re.compile(r'^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$')
+field_size_re = _lazy_re_compile(r'^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$')
 
 
 def get_field_size(name):

django/db/models/sql/constants.py

@@ -2,7 +2,7 @@
 Constants specific to the SQL storage portion of the ORM.
 """
 
-import re
+from django.utils.regex_helper import _lazy_re_compile
 
 # Size of each "chunk" for get_iterator calls.
 # Larger values are slightly faster at the expense of more storage space.
@@ -16,7 +16,7 @@ SINGLE = 'single'
 CURSOR = 'cursor'
 NO_RESULTS = 'no results'
 
-ORDER_PATTERN = re.compile(r'\?|[-+]?[.\w]+$')
+ORDER_PATTERN = _lazy_re_compile(r'\?|[-+]?[.\w]+$')
 ORDER_DIR = {
     'ASC': ('ASC', 'DESC'),
     'DESC': ('DESC', 'ASC'),