53 lines
2.0 KiB
Python
53 lines
2.0 KiB
Python
from django.db import utils
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from django.db.backends.base.features import BaseDatabaseFeatures
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from django.utils.functional import cached_property
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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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max_query_params = 999
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supports_mixed_date_datetime_comparisons = 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_atomic_references_rename = False
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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_table_name_case = True
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supports_cast_with_precision = False
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uses_savepoints = True
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can_release_savepoints = True
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@cached_property
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def supports_stddev(self):
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"""
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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. Manually check 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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