271 lines
11 KiB
Python
271 lines
11 KiB
Python
from django.db.backends.utils import names_digest, split_identifier
|
|
from django.db.models.expressions import Col, ExpressionList, F, Func, OrderBy
|
|
from django.db.models.functions import Collate
|
|
from django.db.models.query_utils import Q
|
|
from django.db.models.sql import Query
|
|
from django.utils.functional import partition
|
|
|
|
__all__ = ['Index']
|
|
|
|
|
|
class Index:
|
|
suffix = 'idx'
|
|
# The max length of the name of the index (restricted to 30 for
|
|
# cross-database compatibility with Oracle)
|
|
max_name_length = 30
|
|
|
|
def __init__(
|
|
self,
|
|
*expressions,
|
|
fields=(),
|
|
name=None,
|
|
db_tablespace=None,
|
|
opclasses=(),
|
|
condition=None,
|
|
include=None,
|
|
):
|
|
if opclasses and not name:
|
|
raise ValueError('An index must be named to use opclasses.')
|
|
if not isinstance(condition, (type(None), Q)):
|
|
raise ValueError('Index.condition must be a Q instance.')
|
|
if condition and not name:
|
|
raise ValueError('An index must be named to use condition.')
|
|
if not isinstance(fields, (list, tuple)):
|
|
raise ValueError('Index.fields must be a list or tuple.')
|
|
if not isinstance(opclasses, (list, tuple)):
|
|
raise ValueError('Index.opclasses must be a list or tuple.')
|
|
if not expressions and not fields:
|
|
raise ValueError(
|
|
'At least one field or expression is required to define an '
|
|
'index.'
|
|
)
|
|
if expressions and fields:
|
|
raise ValueError(
|
|
'Index.fields and expressions are mutually exclusive.',
|
|
)
|
|
if expressions and not name:
|
|
raise ValueError('An index must be named to use expressions.')
|
|
if expressions and opclasses:
|
|
raise ValueError(
|
|
'Index.opclasses cannot be used with expressions. Use '
|
|
'django.contrib.postgres.indexes.OpClass() instead.'
|
|
)
|
|
if opclasses and len(fields) != len(opclasses):
|
|
raise ValueError('Index.fields and Index.opclasses must have the same number of elements.')
|
|
if fields and not all(isinstance(field, str) for field in fields):
|
|
raise ValueError('Index.fields must contain only strings with field names.')
|
|
if include and not name:
|
|
raise ValueError('A covering index must be named.')
|
|
if not isinstance(include, (type(None), list, tuple)):
|
|
raise ValueError('Index.include must be a list or tuple.')
|
|
self.fields = list(fields)
|
|
# A list of 2-tuple with the field name and ordering ('' or 'DESC').
|
|
self.fields_orders = [
|
|
(field_name[1:], 'DESC') if field_name.startswith('-') else (field_name, '')
|
|
for field_name in self.fields
|
|
]
|
|
self.name = name or ''
|
|
self.db_tablespace = db_tablespace
|
|
self.opclasses = opclasses
|
|
self.condition = condition
|
|
self.include = tuple(include) if include else ()
|
|
self.expressions = tuple(
|
|
F(expression) if isinstance(expression, str) else expression
|
|
for expression in expressions
|
|
)
|
|
|
|
@property
|
|
def contains_expressions(self):
|
|
return bool(self.expressions)
|
|
|
|
def _get_condition_sql(self, model, schema_editor):
|
|
if self.condition is None:
|
|
return None
|
|
query = Query(model=model, alias_cols=False)
|
|
where = query.build_where(self.condition)
|
|
compiler = query.get_compiler(connection=schema_editor.connection)
|
|
sql, params = where.as_sql(compiler, schema_editor.connection)
|
|
return sql % tuple(schema_editor.quote_value(p) for p in params)
|
|
|
|
def create_sql(self, model, schema_editor, using='', **kwargs):
|
|
include = [model._meta.get_field(field_name).column for field_name in self.include]
|
|
condition = self._get_condition_sql(model, schema_editor)
|
|
if self.expressions:
|
|
index_expressions = []
|
|
for expression in self.expressions:
|
|
index_expression = IndexExpression(expression)
|
|
index_expression.set_wrapper_classes(schema_editor.connection)
|
|
index_expressions.append(index_expression)
|
|
expressions = ExpressionList(*index_expressions).resolve_expression(
|
|
Query(model, alias_cols=False),
|
|
)
|
|
fields = None
|
|
col_suffixes = None
|
|
else:
|
|
fields = [
|
|
model._meta.get_field(field_name)
|
|
for field_name, _ in self.fields_orders
|
|
]
|
|
col_suffixes = [order[1] for order in self.fields_orders]
|
|
expressions = None
|
|
return schema_editor._create_index_sql(
|
|
model, fields=fields, name=self.name, using=using,
|
|
db_tablespace=self.db_tablespace, col_suffixes=col_suffixes,
|
|
opclasses=self.opclasses, condition=condition, include=include,
|
|
expressions=expressions, **kwargs,
|
|
)
|
|
|
|
def remove_sql(self, model, schema_editor, **kwargs):
|
|
return schema_editor._delete_index_sql(model, self.name, **kwargs)
|
|
|
|
def deconstruct(self):
|
|
path = '%s.%s' % (self.__class__.__module__, self.__class__.__name__)
|
|
path = path.replace('django.db.models.indexes', 'django.db.models')
|
|
kwargs = {'name': self.name}
|
|
if self.fields:
|
|
kwargs['fields'] = self.fields
|
|
if self.db_tablespace is not None:
|
|
kwargs['db_tablespace'] = self.db_tablespace
|
|
if self.opclasses:
|
|
kwargs['opclasses'] = self.opclasses
|
|
if self.condition:
|
|
kwargs['condition'] = self.condition
|
|
if self.include:
|
|
kwargs['include'] = self.include
|
|
return (path, self.expressions, kwargs)
|
|
|
|
def clone(self):
|
|
"""Create a copy of this Index."""
|
|
_, args, kwargs = self.deconstruct()
|
|
return self.__class__(*args, **kwargs)
|
|
|
|
def set_name_with_model(self, model):
|
|
"""
|
|
Generate a unique name for the index.
|
|
|
|
The name is divided into 3 parts - table name (12 chars), field name
|
|
(8 chars) and unique hash + suffix (10 chars). Each part is made to
|
|
fit its size by truncating the excess length.
|
|
"""
|
|
_, table_name = split_identifier(model._meta.db_table)
|
|
column_names = [model._meta.get_field(field_name).column for field_name, order in self.fields_orders]
|
|
column_names_with_order = [
|
|
(('-%s' if order else '%s') % column_name)
|
|
for column_name, (field_name, order) in zip(column_names, self.fields_orders)
|
|
]
|
|
# The length of the parts of the name is based on the default max
|
|
# length of 30 characters.
|
|
hash_data = [table_name] + column_names_with_order + [self.suffix]
|
|
self.name = '%s_%s_%s' % (
|
|
table_name[:11],
|
|
column_names[0][:7],
|
|
'%s_%s' % (names_digest(*hash_data, length=6), self.suffix),
|
|
)
|
|
if len(self.name) > self.max_name_length:
|
|
raise ValueError(
|
|
'Index too long for multiple database support. Is self.suffix '
|
|
'longer than 3 characters?'
|
|
)
|
|
if self.name[0] == '_' or self.name[0].isdigit():
|
|
self.name = 'D%s' % self.name[1:]
|
|
|
|
def __repr__(self):
|
|
return '<%s:%s%s%s%s%s%s%s>' % (
|
|
self.__class__.__qualname__,
|
|
'' if not self.fields else ' fields=%s' % repr(self.fields),
|
|
'' if not self.expressions else ' expressions=%s' % repr(self.expressions),
|
|
'' if not self.name else ' name=%s' % repr(self.name),
|
|
''
|
|
if self.db_tablespace is None
|
|
else ' db_tablespace=%s' % repr(self.db_tablespace),
|
|
'' if self.condition is None else ' condition=%s' % self.condition,
|
|
'' if not self.include else ' include=%s' % repr(self.include),
|
|
'' if not self.opclasses else ' opclasses=%s' % repr(self.opclasses),
|
|
)
|
|
|
|
def __eq__(self, other):
|
|
if self.__class__ == other.__class__:
|
|
return self.deconstruct() == other.deconstruct()
|
|
return NotImplemented
|
|
|
|
|
|
class IndexExpression(Func):
|
|
"""Order and wrap expressions for CREATE INDEX statements."""
|
|
template = '%(expressions)s'
|
|
wrapper_classes = (OrderBy, Collate)
|
|
|
|
def set_wrapper_classes(self, connection=None):
|
|
# Some databases (e.g. MySQL) treats COLLATE as an indexed expression.
|
|
if connection and connection.features.collate_as_index_expression:
|
|
self.wrapper_classes = tuple([
|
|
wrapper_cls
|
|
for wrapper_cls in self.wrapper_classes
|
|
if wrapper_cls is not Collate
|
|
])
|
|
|
|
@classmethod
|
|
def register_wrappers(cls, *wrapper_classes):
|
|
cls.wrapper_classes = wrapper_classes
|
|
|
|
def resolve_expression(
|
|
self,
|
|
query=None,
|
|
allow_joins=True,
|
|
reuse=None,
|
|
summarize=False,
|
|
for_save=False,
|
|
):
|
|
expressions = list(self.flatten())
|
|
# Split expressions and wrappers.
|
|
index_expressions, wrappers = partition(
|
|
lambda e: isinstance(e, self.wrapper_classes),
|
|
expressions,
|
|
)
|
|
wrapper_types = [type(wrapper) for wrapper in wrappers]
|
|
if len(wrapper_types) != len(set(wrapper_types)):
|
|
raise ValueError(
|
|
"Multiple references to %s can't be used in an indexed "
|
|
"expression." % ', '.join([
|
|
wrapper_cls.__qualname__ for wrapper_cls in self.wrapper_classes
|
|
])
|
|
)
|
|
if expressions[1:len(wrappers) + 1] != wrappers:
|
|
raise ValueError(
|
|
'%s must be topmost expressions in an indexed expression.'
|
|
% ', '.join([
|
|
wrapper_cls.__qualname__ for wrapper_cls in self.wrapper_classes
|
|
])
|
|
)
|
|
# Wrap expressions in parentheses if they are not column references.
|
|
root_expression = index_expressions[1]
|
|
resolve_root_expression = root_expression.resolve_expression(
|
|
query,
|
|
allow_joins,
|
|
reuse,
|
|
summarize,
|
|
for_save,
|
|
)
|
|
if not isinstance(resolve_root_expression, Col):
|
|
root_expression = Func(root_expression, template='(%(expressions)s)')
|
|
|
|
if wrappers:
|
|
# Order wrappers and set their expressions.
|
|
wrappers = sorted(
|
|
wrappers,
|
|
key=lambda w: self.wrapper_classes.index(type(w)),
|
|
)
|
|
wrappers = [wrapper.copy() for wrapper in wrappers]
|
|
for i, wrapper in enumerate(wrappers[:-1]):
|
|
wrapper.set_source_expressions([wrappers[i + 1]])
|
|
# Set the root expression on the deepest wrapper.
|
|
wrappers[-1].set_source_expressions([root_expression])
|
|
self.set_source_expressions([wrappers[0]])
|
|
else:
|
|
# Use the root expression, if there are no wrappers.
|
|
self.set_source_expressions([root_expression])
|
|
return super().resolve_expression(query, allow_joins, reuse, summarize, for_save)
|
|
|
|
def as_sqlite(self, compiler, connection, **extra_context):
|
|
# Casting to numeric is unnecessary.
|
|
return self.as_sql(compiler, connection, **extra_context)
|