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@ -1,6 +1,8 @@
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import datetime
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import decimal
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import uuid
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from functools import lru_cache
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from itertools import chain
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from django.conf import settings
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from django.core.exceptions import FieldError
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@ -11,6 +13,7 @@ from django.db.models.expressions import Col
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from django.utils import timezone
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from django.utils.dateparse import parse_date, parse_datetime, parse_time
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from django.utils.duration import duration_microseconds
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from django.utils.functional import cached_property
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class DatabaseOperations(BaseDatabaseOperations):
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@ -158,28 +161,36 @@ class DatabaseOperations(BaseDatabaseOperations):
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def no_limit_value(self):
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return -1
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def __references_graph(self, table_name):
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query = """
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WITH tables AS (
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SELECT %s name
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UNION
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SELECT sqlite_master.name
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FROM sqlite_master
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JOIN tables ON (sql REGEXP %s || tables.name || %s)
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) SELECT name FROM tables;
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"""
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params = (
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table_name,
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r'(?i)\s+references\s+("|\')?',
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r'("|\')?\s*\(',
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)
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with self.connection.cursor() as cursor:
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results = cursor.execute(query, params)
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return [row[0] for row in results.fetchall()]
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@cached_property
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def _references_graph(self):
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# 512 is large enough to fit the ~330 tables (as of this writing) in
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# Django's test suite.
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return lru_cache(maxsize=512)(self.__references_graph)
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def sql_flush(self, style, tables, sequences, allow_cascade=False):
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if tables and allow_cascade:
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# Simulate TRUNCATE CASCADE by recursively collecting the tables
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# referencing the tables to be flushed.
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query = """
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WITH tables AS (
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%s
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UNION
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SELECT sqlite_master.name
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FROM sqlite_master
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JOIN tables ON (
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sql REGEXP %%s || tables.name || %%s
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)
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) SELECT name FROM tables;
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""" % ' UNION '.join("SELECT '%s' name" % table for table in tables)
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params = (
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r'(?i)\s+references\s+("|\')?',
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r'("|\')?\s*\(',
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)
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with self.connection.cursor() as cursor:
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results = cursor.execute(query, params)
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tables = [row[0] for row in results.fetchall()]
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tables = set(chain.from_iterable(self._references_graph(table) for table in tables))
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sql = ['%s %s %s;' % (
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style.SQL_KEYWORD('DELETE'),
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style.SQL_KEYWORD('FROM'),
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