86 lines
2.8 KiB
Python
86 lines
2.8 KiB
Python
from __future__ import unicode_literals
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from django.db import utils
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from django.db.backends.base.features import BaseDatabaseFeatures
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from django.utils import six
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from django.utils.functional import cached_property
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from .base import Database
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try:
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import pytz
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except ImportError:
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pytz = None
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class DatabaseFeatures(BaseDatabaseFeatures):
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# SQLite cannot handle us only partially reading from a cursor's result set
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# and then writing the same rows to the database in another cursor. This
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# setting ensures we always read result sets fully into memory all in one
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# go.
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can_use_chunked_reads = False
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test_db_allows_multiple_connections = False
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supports_unspecified_pk = True
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supports_timezones = False
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supports_1000_query_parameters = False
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supports_mixed_date_datetime_comparisons = False
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has_bulk_insert = True
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can_combine_inserts_with_and_without_auto_increment_pk = False
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supports_foreign_keys = False
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supports_column_check_constraints = False
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autocommits_when_autocommit_is_off = True
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can_introspect_decimal_field = False
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can_introspect_positive_integer_field = True
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can_introspect_small_integer_field = True
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supports_transactions = True
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atomic_transactions = False
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can_rollback_ddl = True
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supports_paramstyle_pyformat = False
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supports_sequence_reset = False
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can_clone_databases = True
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supports_temporal_subtraction = True
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ignores_quoted_identifier_case = True
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@cached_property
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def uses_savepoints(self):
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return Database.sqlite_version_info >= (3, 6, 8)
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@cached_property
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def supports_index_column_ordering(self):
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return Database.sqlite_version_info >= (3, 3, 0)
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@cached_property
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def can_release_savepoints(self):
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return self.uses_savepoints
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@cached_property
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def can_share_in_memory_db(self):
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return (
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six.PY3 and
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Database.__name__ == 'sqlite3.dbapi2' and
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Database.sqlite_version_info >= (3, 7, 13)
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)
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@cached_property
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def supports_stddev(self):
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"""Confirm support for STDDEV and related stats functions
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SQLite supports STDDEV as an extension package; so
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connection.ops.check_expression_support() can't unilaterally
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rule out support for STDDEV. We need to manually check
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whether the call works.
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"""
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with self.connection.cursor() as cursor:
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cursor.execute('CREATE TABLE STDDEV_TEST (X INT)')
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try:
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cursor.execute('SELECT STDDEV(*) FROM STDDEV_TEST')
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has_support = True
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except utils.DatabaseError:
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has_support = False
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cursor.execute('DROP TABLE STDDEV_TEST')
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return has_support
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@cached_property
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def has_zoneinfo_database(self):
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return pytz is not None
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