From 13b7f299de79e3eb101c3f015386eba39a8f3928 Mon Sep 17 00:00:00 2001 From: Aymeric Augustin Date: Sun, 9 Jun 2013 21:04:36 +0200 Subject: [PATCH] Added a stealth option to flush to allow cascades. This allows using flush on a subset of the tables without having to manually cascade to all tables with foreign keys to the tables being truncated, when they're known to be empty. On databases where truncate is implemented with DELETE FROM, this doesn't make a difference. The cascade is allowed, not mandatory. --- django/core/management/commands/flush.py | 7 +++++-- django/core/management/sql.py | 4 ++-- django/db/backends/__init__.py | 8 ++++++-- django/db/backends/mysql/base.py | 7 +++++-- django/db/backends/oracle/base.py | 12 ++++++------ .../postgresql_psycopg2/operations.py | 19 ++++++++++++++----- django/db/backends/sqlite3/base.py | 12 ++++++------ 7 files changed, 44 insertions(+), 25 deletions(-) diff --git a/django/core/management/commands/flush.py b/django/core/management/commands/flush.py index c56fc1e1b0f..7054187e45b 100644 --- a/django/core/management/commands/flush.py +++ b/django/core/management/commands/flush.py @@ -32,8 +32,9 @@ class Command(NoArgsCommand): connection = connections[db] verbosity = int(options.get('verbosity')) interactive = options.get('interactive') - # 'reset_sequences' is a stealth option + # 'reset_sequences' and 'allow_cascade' are stealth options reset_sequences = options.get('reset_sequences', True) + allow_cascade = options.get('allow_cascade', False) self.style = no_style() @@ -45,7 +46,9 @@ class Command(NoArgsCommand): except ImportError: pass - sql_list = sql_flush(self.style, connection, only_django=True, reset_sequences=reset_sequences) + sql_list = sql_flush(self.style, connection, only_django=True, + reset_sequences=reset_sequences, + allow_cascade=allow_cascade) if interactive: confirm = input("""You have requested a flush of the database. diff --git a/django/core/management/sql.py b/django/core/management/sql.py index 42ccafa2c56..b58d89f60ab 100644 --- a/django/core/management/sql.py +++ b/django/core/management/sql.py @@ -102,7 +102,7 @@ def sql_delete(app, style, connection): return output[::-1] # Reverse it, to deal with table dependencies. -def sql_flush(style, connection, only_django=False, reset_sequences=True): +def sql_flush(style, connection, only_django=False, reset_sequences=True, allow_cascade=False): """ Returns a list of the SQL statements used to flush the database. @@ -114,7 +114,7 @@ def sql_flush(style, connection, only_django=False, reset_sequences=True): else: tables = connection.introspection.table_names() seqs = connection.introspection.sequence_list() if reset_sequences else () - statements = connection.ops.sql_flush(style, tables, seqs) + statements = connection.ops.sql_flush(style, tables, seqs, allow_cascade) return statements diff --git a/django/db/backends/__init__.py b/django/db/backends/__init__.py index 160c63d9d93..fa3cc5ac02c 100644 --- a/django/db/backends/__init__.py +++ b/django/db/backends/__init__.py @@ -390,7 +390,7 @@ class BaseDatabaseWrapper(object): def disable_constraint_checking(self): """ Backends can implement as needed to temporarily disable foreign key - constraint checking. Should return True if the constraints were + constraint checking. Should return True if the constraints were disabled and will need to be reenabled. """ return False @@ -947,7 +947,7 @@ class BaseDatabaseOperations(object): """ return '' - def sql_flush(self, style, tables, sequences): + def sql_flush(self, style, tables, sequences, allow_cascade=False): """ Returns a list of SQL statements required to remove all data from the given database tables (without actually removing the tables @@ -958,6 +958,10 @@ class BaseDatabaseOperations(object): The `style` argument is a Style object as returned by either color_style() or no_style() in django.core.management.color. + + The `allow_cascade` argument determines whether truncation may cascade + to tables with foreign keys pointing the tables being truncated. + PostgreSQL requires a cascade even if these tables are empty. """ raise NotImplementedError() diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py index dbddad73127..ea687715e4e 100644 --- a/django/db/backends/mysql/base.py +++ b/django/db/backends/mysql/base.py @@ -298,14 +298,17 @@ class DatabaseOperations(BaseDatabaseOperations): def random_function_sql(self): return 'RAND()' - def sql_flush(self, style, tables, sequences): + def sql_flush(self, style, tables, sequences, allow_cascade=False): # NB: The generated SQL below is specific to MySQL # 'TRUNCATE x;', 'TRUNCATE y;', 'TRUNCATE z;'... style SQL statements # to clear all tables of all data if tables: sql = ['SET FOREIGN_KEY_CHECKS = 0;'] for table in tables: - sql.append('%s %s;' % (style.SQL_KEYWORD('TRUNCATE'), style.SQL_FIELD(self.quote_name(table)))) + sql.append('%s %s;' % ( + style.SQL_KEYWORD('TRUNCATE'), + style.SQL_FIELD(self.quote_name(table)), + )) sql.append('SET FOREIGN_KEY_CHECKS = 1;') sql.extend(self.sequence_reset_by_name_sql(style, sequences)) return sql diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py index 0afc5f23e8d..3f39a15aa7c 100644 --- a/django/db/backends/oracle/base.py +++ b/django/db/backends/oracle/base.py @@ -339,17 +339,17 @@ WHEN (new.%(col_name)s IS NULL) def savepoint_rollback_sql(self, sid): return convert_unicode("ROLLBACK TO SAVEPOINT " + self.quote_name(sid)) - def sql_flush(self, style, tables, sequences): + def sql_flush(self, style, tables, sequences, allow_cascade=False): # Return a list of 'TRUNCATE x;', 'TRUNCATE y;', # 'TRUNCATE z;'... style SQL statements if tables: # Oracle does support TRUNCATE, but it seems to get us into # FK referential trouble, whereas DELETE FROM table works. - sql = ['%s %s %s;' % \ - (style.SQL_KEYWORD('DELETE'), - style.SQL_KEYWORD('FROM'), - style.SQL_FIELD(self.quote_name(table))) - for table in tables] + sql = ['%s %s %s;' % ( + style.SQL_KEYWORD('DELETE'), + style.SQL_KEYWORD('FROM'), + style.SQL_FIELD(self.quote_name(table)) + ) for table in tables] # Since we've just deleted all the rows, running our sequence # ALTER code will reset the sequence to 0. sql.extend(self.sequence_reset_by_name_sql(style, sequences)) diff --git a/django/db/backends/postgresql_psycopg2/operations.py b/django/db/backends/postgresql_psycopg2/operations.py index f06eec5a1d2..f96757da8b3 100644 --- a/django/db/backends/postgresql_psycopg2/operations.py +++ b/django/db/backends/postgresql_psycopg2/operations.py @@ -101,15 +101,24 @@ class DatabaseOperations(BaseDatabaseOperations): def set_time_zone_sql(self): return "SET TIME ZONE %s" - def sql_flush(self, style, tables, sequences): + def sql_flush(self, style, tables, sequences, allow_cascade=False): if tables: # Perform a single SQL 'TRUNCATE x, y, z...;' statement. It allows # us to truncate tables referenced by a foreign key in any other # table. - sql = ['%s %s;' % \ - (style.SQL_KEYWORD('TRUNCATE'), - style.SQL_FIELD(', '.join([self.quote_name(table) for table in tables])) - )] + tables_sql = ', '.join( + style.SQL_FIELD(self.quote_name(table)) for table in tables) + if allow_cascade: + sql = ['%s %s %s;' % ( + style.SQL_KEYWORD('TRUNCATE'), + tables_sql, + style.SQL_KEYWORD('CASCADE'), + )] + else: + sql = ['%s %s;' % ( + style.SQL_KEYWORD('TRUNCATE'), + tables_sql, + )] sql.extend(self.sequence_reset_by_name_sql(style, sequences)) return sql else: diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py index ead325a33b1..a2d925ac3f8 100644 --- a/django/db/backends/sqlite3/base.py +++ b/django/db/backends/sqlite3/base.py @@ -209,15 +209,15 @@ class DatabaseOperations(BaseDatabaseOperations): def no_limit_value(self): return -1 - def sql_flush(self, style, tables, sequences): + def sql_flush(self, style, tables, sequences, allow_cascade=False): # NB: The generated SQL below is specific to SQLite # Note: The DELETE FROM... SQL generated below works for SQLite databases # because constraints don't exist - sql = ['%s %s %s;' % \ - (style.SQL_KEYWORD('DELETE'), - style.SQL_KEYWORD('FROM'), - style.SQL_FIELD(self.quote_name(table)) - ) for table in tables] + sql = ['%s %s %s;' % ( + style.SQL_KEYWORD('DELETE'), + style.SQL_KEYWORD('FROM'), + style.SQL_FIELD(self.quote_name(table)) + ) for table in tables] # Note: No requirement for reset of auto-incremented indices (cf. other # sql_flush() implementations). Just return SQL at this point return sql