import psycopg2 from django.db.backends.base.schema import BaseDatabaseSchemaEditor from django.db.backends.ddl_references import IndexColumns from django.db.backends.utils import strip_quotes class DatabaseSchemaEditor(BaseDatabaseSchemaEditor): sql_create_sequence = "CREATE SEQUENCE %(sequence)s" sql_delete_sequence = "DROP SEQUENCE IF EXISTS %(sequence)s CASCADE" sql_set_sequence_max = "SELECT setval('%(sequence)s', MAX(%(column)s)) FROM %(table)s" sql_set_sequence_owner = 'ALTER SEQUENCE %(sequence)s OWNED BY %(table)s.%(column)s' sql_create_index = "CREATE INDEX %(name)s ON %(table)s%(using)s (%(columns)s)%(extra)s%(condition)s" sql_create_index_concurrently = ( "CREATE INDEX CONCURRENTLY %(name)s ON %(table)s%(using)s (%(columns)s)%(extra)s%(condition)s" ) sql_delete_index = "DROP INDEX IF EXISTS %(name)s" sql_delete_index_concurrently = "DROP INDEX CONCURRENTLY IF EXISTS %(name)s" # Setting the constraint to IMMEDIATE to allow changing data in the same # transaction. sql_create_column_inline_fk = ( 'CONSTRAINT %(name)s REFERENCES %(to_table)s(%(to_column)s)%(deferrable)s' '; SET CONSTRAINTS %(namespace)s%(name)s IMMEDIATE' ) # Setting the constraint to IMMEDIATE runs any deferred checks to allow # dropping it in the same transaction. sql_delete_fk = "SET CONSTRAINTS %(name)s IMMEDIATE; ALTER TABLE %(table)s DROP CONSTRAINT %(name)s" sql_delete_procedure = 'DROP FUNCTION %(procedure)s(%(param_types)s)' def quote_value(self, value): if isinstance(value, str): value = value.replace('%', '%%') # getquoted() returns a quoted bytestring of the adapted value. return psycopg2.extensions.adapt(value).getquoted().decode() def _field_indexes_sql(self, model, field): output = super()._field_indexes_sql(model, field) like_index_statement = self._create_like_index_sql(model, field) if like_index_statement is not None: output.append(like_index_statement) return output def _field_data_type(self, field): if field.is_relation: return field.rel_db_type(self.connection) return self.connection.data_types.get( field.get_internal_type(), field.db_type(self.connection), ) def _field_base_data_types(self, field): # Yield base data types for array fields. if field.base_field.get_internal_type() == 'ArrayField': yield from self._field_base_data_types(field.base_field) else: yield self._field_data_type(field.base_field) def _create_like_index_sql(self, model, field): """ Return the statement to create an index with varchar operator pattern when the column type is 'varchar' or 'text', otherwise return None. """ db_type = field.db_type(connection=self.connection) if db_type is not None and (field.db_index or field.unique): # Fields with database column types of `varchar` and `text` need # a second index that specifies their operator class, which is # needed when performing correct LIKE queries outside the # C locale. See #12234. # # The same doesn't apply to array fields such as varchar[size] # and text[size], so skip them. if '[' in db_type: return None if db_type.startswith('varchar'): return self._create_index_sql(model, [field], suffix='_like', opclasses=['varchar_pattern_ops']) elif db_type.startswith('text'): return self._create_index_sql(model, [field], suffix='_like', opclasses=['text_pattern_ops']) return None def _alter_column_type_sql(self, model, old_field, new_field, new_type): self.sql_alter_column_type = 'ALTER COLUMN %(column)s TYPE %(type)s' # Cast when data type changed. using_sql = ' USING %(column)s::%(type)s' new_internal_type = new_field.get_internal_type() old_internal_type = old_field.get_internal_type() if new_internal_type == 'ArrayField' and new_internal_type == old_internal_type: # Compare base data types for array fields. if list(self._field_base_data_types(old_field)) != list(self._field_base_data_types(new_field)): self.sql_alter_column_type += using_sql elif self._field_data_type(old_field) != self._field_data_type(new_field): self.sql_alter_column_type += using_sql # Make ALTER TYPE with SERIAL make sense. table = strip_quotes(model._meta.db_table) serial_fields_map = {'bigserial': 'bigint', 'serial': 'integer', 'smallserial': 'smallint'} if new_type.lower() in serial_fields_map: column = strip_quotes(new_field.column) sequence_name = "%s_%s_seq" % (table, column) return ( ( self.sql_alter_column_type % { "column": self.quote_name(column), "type": serial_fields_map[new_type.lower()], }, [], ), [ ( self.sql_delete_sequence % { "sequence": self.quote_name(sequence_name), }, [], ), ( self.sql_create_sequence % { "sequence": self.quote_name(sequence_name), }, [], ), ( self.sql_alter_column % { "table": self.quote_name(table), "changes": self.sql_alter_column_default % { "column": self.quote_name(column), "default": "nextval('%s')" % self.quote_name(sequence_name), } }, [], ), ( self.sql_set_sequence_max % { "table": self.quote_name(table), "column": self.quote_name(column), "sequence": self.quote_name(sequence_name), }, [], ), ( self.sql_set_sequence_owner % { 'table': self.quote_name(table), 'column': self.quote_name(column), 'sequence': self.quote_name(sequence_name), }, [], ), ], ) else: return super()._alter_column_type_sql(model, old_field, new_field, new_type) def _alter_field(self, model, old_field, new_field, old_type, new_type, old_db_params, new_db_params, strict=False): # Drop indexes on varchar/text/citext columns that are changing to a # different type. if (old_field.db_index or old_field.unique) and ( (old_type.startswith('varchar') and not new_type.startswith('varchar')) or (old_type.startswith('text') and not new_type.startswith('text')) or (old_type.startswith('citext') and not new_type.startswith('citext')) ): index_name = self._create_index_name(model._meta.db_table, [old_field.column], suffix='_like') self.execute(self._delete_index_sql(model, index_name)) super()._alter_field( model, old_field, new_field, old_type, new_type, old_db_params, new_db_params, strict, ) # Added an index? Create any PostgreSQL-specific indexes. if ((not (old_field.db_index or old_field.unique) and new_field.db_index) or (not old_field.unique and new_field.unique)): like_index_statement = self._create_like_index_sql(model, new_field) if like_index_statement is not None: self.execute(like_index_statement) # Removed an index? Drop any PostgreSQL-specific indexes. if old_field.unique and not (new_field.db_index or new_field.unique): index_to_remove = self._create_index_name(model._meta.db_table, [old_field.column], suffix='_like') self.execute(self._delete_index_sql(model, index_to_remove)) def _index_columns(self, table, columns, col_suffixes, opclasses): if opclasses: return IndexColumns(table, columns, self.quote_name, col_suffixes=col_suffixes, opclasses=opclasses) return super()._index_columns(table, columns, col_suffixes, opclasses) def add_index(self, model, index, concurrently=False): self.execute(index.create_sql(model, self, concurrently=concurrently), params=None) def remove_index(self, model, index, concurrently=False): self.execute(index.remove_sql(model, self, concurrently=concurrently)) def _delete_index_sql(self, model, name, sql=None, concurrently=False): sql = self.sql_delete_index_concurrently if concurrently else self.sql_delete_index return super()._delete_index_sql(model, name, sql) def _create_index_sql( self, model, fields, *, name=None, suffix='', using='', db_tablespace=None, col_suffixes=(), sql=None, opclasses=(), condition=None, concurrently=False, ): sql = self.sql_create_index if not concurrently else self.sql_create_index_concurrently return super()._create_index_sql( model, fields, name=name, suffix=suffix, using=using, db_tablespace=db_tablespace, col_suffixes=col_suffixes, sql=sql, opclasses=opclasses, condition=condition, )