import re from django.db.backends import BaseDatabaseOperations # This DatabaseOperations class lives in here instead of base.py because it's # used by both the 'postgresql' and 'postgresql_psycopg2' backends. class DatabaseOperations(BaseDatabaseOperations): def __init__(self): self._postgres_version = None def _get_postgres_version(self): if self._postgres_version is None: from django.db import connection from django.db.backends.postgresql.version import get_version cursor = connection.cursor() self._postgres_version = get_version(cursor) return self._postgres_version postgres_version = property(_get_postgres_version) def date_extract_sql(self, lookup_type, field_name): # http://www.postgresql.org/docs/8.0/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT if lookup_type == 'week_day': # For consistency across backends, we return Sunday=1, Saturday=7. return "EXTRACT('dow' FROM %s) + 1" % field_name else: return "EXTRACT('%s' FROM %s)" % (lookup_type, field_name) def date_trunc_sql(self, lookup_type, field_name): # http://www.postgresql.org/docs/8.0/static/functions-datetime.html#FUNCTIONS-DATETIME-TRUNC return "DATE_TRUNC('%s', %s)" % (lookup_type, field_name) def deferrable_sql(self): return " DEFERRABLE INITIALLY DEFERRED" def lookup_cast(self, lookup_type): lookup = '%s' # Cast text lookups to text to allow things like filter(x__contains=4) if lookup_type in ('iexact', 'contains', 'icontains', 'startswith', 'istartswith', 'endswith', 'iendswith'): lookup = "%s::text" # Use UPPER(x) for case-insensitive lookups; it's faster. if lookup_type in ('iexact', 'icontains', 'istartswith', 'iendswith'): lookup = 'UPPER(%s)' % lookup return lookup def field_cast_sql(self, db_type): if db_type == 'inet': return 'HOST(%s)' return '%s' def last_insert_id(self, cursor, table_name, pk_name): cursor.execute("SELECT CURRVAL('\"%s_%s_seq\"')" % (table_name, pk_name)) return cursor.fetchone()[0] def no_limit_value(self): return None def quote_name(self, name): if name.startswith('"') and name.endswith('"'): return name # Quoting once is enough. return '"%s"' % name def sql_flush(self, style, tables, sequences): if tables: if self.postgres_version[0:2] >= (8,1): # Postgres 8.1+ can do 'TRUNCATE x, y, z...;'. In fact, it *has to* # in order to be able to truncate tables referenced by a foreign # key in any other table. The result is a single SQL TRUNCATE # statement. sql = ['%s %s;' % \ (style.SQL_KEYWORD('TRUNCATE'), style.SQL_FIELD(', '.join([self.quote_name(table) for table in tables])) )] else: # Older versions of Postgres can't do TRUNCATE in a single call, so # they must use a simple delete. sql = ['%s %s %s;' % \ (style.SQL_KEYWORD('DELETE'), style.SQL_KEYWORD('FROM'), style.SQL_FIELD(self.quote_name(table)) ) for table in tables] # 'ALTER SEQUENCE sequence_name RESTART WITH 1;'... style SQL statements # to reset sequence indices for sequence_info in sequences: table_name = sequence_info['table'] column_name = sequence_info['column'] if column_name and len(column_name) > 0: sequence_name = '%s_%s_seq' % (table_name, column_name) else: sequence_name = '%s_id_seq' % table_name sql.append("%s setval('%s', 1, false);" % \ (style.SQL_KEYWORD('SELECT'), style.SQL_FIELD(self.quote_name(sequence_name))) ) return sql else: return [] def sequence_reset_sql(self, style, model_list): from django.db import models output = [] qn = self.quote_name for model in model_list: # Use `coalesce` to set the sequence for each model to the max pk value if there are records, # or 1 if there are none. Set the `is_called` property (the third argument to `setval`) to true # if there are records (as the max pk value is already in use), otherwise set it to false. for f in model._meta.local_fields: if isinstance(f, models.AutoField): output.append("%s setval('%s', coalesce(max(%s), 1), max(%s) %s null) %s %s;" % \ (style.SQL_KEYWORD('SELECT'), style.SQL_FIELD(qn('%s_%s_seq' % (model._meta.db_table, f.column))), style.SQL_FIELD(qn(f.column)), style.SQL_FIELD(qn(f.column)), style.SQL_KEYWORD('IS NOT'), style.SQL_KEYWORD('FROM'), style.SQL_TABLE(qn(model._meta.db_table)))) break # Only one AutoField is allowed per model, so don't bother continuing. for f in model._meta.many_to_many: output.append("%s setval('%s', coalesce(max(%s), 1), max(%s) %s null) %s %s;" % \ (style.SQL_KEYWORD('SELECT'), style.SQL_FIELD(qn('%s_id_seq' % f.m2m_db_table())), style.SQL_FIELD(qn('id')), style.SQL_FIELD(qn('id')), style.SQL_KEYWORD('IS NOT'), style.SQL_KEYWORD('FROM'), style.SQL_TABLE(qn(f.m2m_db_table())))) return output def savepoint_create_sql(self, sid): return "SAVEPOINT %s" % sid def savepoint_commit_sql(self, sid): return "RELEASE SAVEPOINT %s" % sid def savepoint_rollback_sql(self, sid): return "ROLLBACK TO SAVEPOINT %s" % sid def prep_for_iexact_query(self, x): return x def check_aggregate_support(self, aggregate): """Check that the backend fully supports the provided aggregate. The population and sample statistics (STDDEV_POP, STDDEV_SAMP, VAR_POP, VAR_SAMP) were first implemented in Postgres 8.2. The implementation of population statistics (STDDEV_POP and VAR_POP) under Postgres 8.2 - 8.2.4 is known to be faulty. Raise NotImplementedError if this is the database in use. """ if aggregate.sql_function in ('STDDEV_POP', 'STDDEV_SAMP', 'VAR_POP', 'VAR_SAMP'): if self.postgres_version[0:2] < (8,2): raise NotImplementedError('PostgreSQL does not support %s prior to version 8.2. Please upgrade your version of PostgreSQL.' % aggregate.sql_function) if aggregate.sql_function in ('STDDEV_POP', 'VAR_POP'): if self.postgres_version[0:2] == (8,2): if self.postgres_version[2] is None or self.postgres_version[2] <= 4: raise NotImplementedError('PostgreSQL 8.2 to 8.2.4 is known to have a faulty implementation of %s. Please upgrade your version of PostgreSQL.' % aggregate.sql_function)