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Refs #20483 -- Implemented cascaded flush on Oracle. 

The initial implementation added support for PostgreSQL but it is also required
on Oracle (13b7f299de).

Thanks Mariusz Felisiak for the foreign key retreival queries.
This commit is contained in:
Simon Charette 2016-05-20 17:33:10 -04:00
parent 974d14534c
commit 973cfd2ef5
1 changed files with 74 additions and 9 deletions
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83
django/db/backends/oracle/operations.py
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@ -315,17 +315,82 @@ WHEN (new.%(col_name)s IS NULL)
def savepoint_rollback_sql(self, sid):
return "ROLLBACK TO SAVEPOINT " + self.quote_name(sid)
def _foreign_key_constraints(self, table_name, recursive=False):
with self.connection.cursor() as cursor:
if recursive:
cursor.execute("""
SELECT
user_tables.table_name, rcons.constraint_name, MAX(level)
FROM
user_tables
JOIN
user_constraints cons
ON (user_tables.table_name = cons.table_name AND cons.constraint_type = ANY('P', 'U'))
LEFT JOIN
user_constraints rcons
ON (user_tables.table_name = rcons.table_name AND rcons.constraint_type = 'R')
START WITH user_tables.table_name = UPPER(%s)
CONNECT BY NOCYCLE PRIOR cons.constraint_name = rcons.r_constraint_name
GROUP BY
user_tables.table_name, rcons.constraint_name
HAVING user_tables.table_name != UPPER(%s)
ORDER BY MAX(level) DESC
""", (table_name, table_name))
else:
cursor.execute("""
SELECT
cons.table_name, cons.constraint_name, 1
FROM
user_constraints cons
WHERE
cons.constraint_type = 'R'
AND cons.table_name = UPPER(%s)
""", (table_name,))
return [
(foreign_table, constraint) for foreign_table, constraint, _ in cursor.fetchall()
]
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]
truncated_tables = {table.upper() for table in tables}
constraints = set()
# Oracle's TRUNCATE CASCADE only works with ON DELETE CASCADE
# foreign keys which Django doesn't define. Emulate the
# PostgreSQL behavior which truncates all dependent tables by
# manually retrieving all foreign key constraints and resolving
# dependencies.
for table in tables:
for foreign_table, constraint in self._foreign_key_constraints(table, recursive=allow_cascade):
if allow_cascade:
truncated_tables.add(foreign_table)
constraints.add((foreign_table, constraint))
sql = [
"%s %s %s %s %s %s %s %s;" % (
style.SQL_KEYWORD('ALTER'),
style.SQL_KEYWORD('TABLE'),
style.SQL_FIELD(self.quote_name(table)),
style.SQL_KEYWORD('DISABLE'),
style.SQL_KEYWORD('CONSTRAINT'),
style.SQL_FIELD(self.quote_name(constraint)),
style.SQL_KEYWORD('KEEP'),
style.SQL_KEYWORD('INDEX'),
) for table, constraint in constraints
] + [
"%s %s %s;" % (
style.SQL_KEYWORD('TRUNCATE'),
style.SQL_KEYWORD('TABLE'),
style.SQL_FIELD(self.quote_name(table)),
) for table in truncated_tables
] + [
"%s %s %s %s %s %s;" % (
style.SQL_KEYWORD('ALTER'),
style.SQL_KEYWORD('TABLE'),
style.SQL_FIELD(self.quote_name(table)),
style.SQL_KEYWORD('ENABLE'),
style.SQL_KEYWORD('CONSTRAINT'),
style.SQL_FIELD(self.quote_name(constraint)),
) for table, constraint in constraints
]
# 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))