diff options
Diffstat (limited to 'webapp/django/db/backends/postgresql/operations.py')
| -rw-r--r-- | webapp/django/db/backends/postgresql/operations.py | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/webapp/django/db/backends/postgresql/operations.py b/webapp/django/db/backends/postgresql/operations.py new file mode 100644 index 0000000000..01cc1fc8b7 --- /dev/null +++ b/webapp/django/db/backends/postgresql/operations.py @@ -0,0 +1,144 @@ +import re + +from django.db.backends import BaseDatabaseOperations + +server_version_re = re.compile(r'PostgreSQL (\d{1,2})\.(\d{1,2})\.?(\d{1,2})?') + +# 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 + cursor = connection.cursor() + cursor.execute("SELECT version()") + version_string = cursor.fetchone()[0] + m = server_version_re.match(version_string) + if not m: + raise Exception('Unable to determine PostgreSQL version from version() function string: %r' % version_string) + self._postgres_version = [int(val) for val in m.groups() if val] + 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 + 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] >= 8 and self.postgres_version[1] >= 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 + |