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import psycopg2
from django.db.backends.base.schema import BaseDatabaseSchemaEditor
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_create_varchar_index = "CREATE INDEX %(name)s ON %(table)s (%(columns)s varchar_pattern_ops)%(extra)s"
sql_create_text_index = "CREATE INDEX %(name)s ON %(table)s (%(columns)s text_pattern_ops)%(extra)s"
def quote_value(self, value):
return psycopg2.extensions.adapt(value)
def _model_indexes_sql(self, model):
output = super(DatabaseSchemaEditor, self)._model_indexes_sql(model)
if not model._meta.managed or model._meta.proxy or model._meta.swapped:
return output
for field in model._meta.local_fields:
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.
if db_type.startswith('varchar'):
output.append(self._create_index_sql(
model, [field], suffix='_like', sql=self.sql_create_varchar_index))
elif db_type.startswith('text'):
output.append(self._create_index_sql(
model, [field], suffix='_like', sql=self.sql_create_text_index))
return output
def _alter_column_type_sql(self, table, old_field, new_field, new_type):
"""
Makes ALTER TYPE with SERIAL make sense.
"""
if new_type.lower() == "serial":
column = new_field.column
sequence_name = "%s_%s_seq" % (table, column)
return (
(
self.sql_alter_column_type % {
"column": self.quote_name(column),
"type": "integer",
},
[],
),
[
(
self.sql_delete_sequence % {
"sequence": sequence_name,
},
[],
),
(
self.sql_create_sequence % {
"sequence": sequence_name,
},
[],
),
(
self.sql_alter_column % {
"table": table,
"changes": self.sql_alter_column_default % {
"column": column,
"default": "nextval('%s')" % sequence_name,
}
},
[],
),
(
self.sql_set_sequence_max % {
"table": table,
"column": column,
"sequence": sequence_name,
},
[],
),
],
)
else:
return super(DatabaseSchemaEditor, self)._alter_column_type_sql(
table, old_field, new_field, new_type
)
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