"""plan execution of rql queries on a single source
:organization: Logilab
:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"
from copy import copy
from rql.stmts import Union, Select
from rql.nodes import Constant
from cubicweb import QueryError, typed_eid
from cubicweb.schema import VIRTUAL_RTYPES
from cubicweb.rqlrewrite import add_types_restriction
class SSPlanner(object):
"""SingleSourcePlanner: build execution plan for rql queries
optimized for single source repositories
"""
def __init__(self, schema, rqlhelper):
self.schema = schema
self.rqlhelper = rqlhelper
def build_plan(self, plan):
"""build an execution plan from a RQL query
do nothing here, dispatch according to the statement type
"""
build_plan = getattr(self, 'build_%s_plan' % plan.rqlst.TYPE)
for step in build_plan(plan, plan.rqlst):
plan.add_step(step)
def build_select_plan(self, plan, rqlst):
"""build execution plan for a SELECT RQL query. Suppose only one source
is available and so avoid work need for query decomposition among sources
the rqlst should not be tagged at this point.
"""
plan.preprocess(rqlst)
return (OneFetchStep(plan, rqlst, plan.session.repo.sources),)
def build_insert_plan(self, plan, rqlst):
"""get an execution plan from an INSERT RQL query"""
# each variable in main variables is a new entity to insert
to_build = {}
session = plan.session
etype_class = session.vreg['etypes'].etype_class
for etype, var in rqlst.main_variables:
# need to do this since entity class is shared w. web client code !
to_build[var.name] = etype_class(etype)(session)
plan.add_entity_def(to_build[var.name])
# add constant values to entity def, mark variables to be selected
to_select = plan.relation_definitions(rqlst, to_build)
# add necessary steps to add relations and update attributes
step = InsertStep(plan) # insert each entity and its relations
step.children += self._compute_relation_steps(plan, rqlst.solutions,
rqlst.where, to_select)
return (step,)
def _compute_relation_steps(self, plan, solutions, restriction, to_select):
"""handle the selection of relations for an insert query"""
for edef, rdefs in to_select.items():
# create a select rql st to fetch needed data
select = Select()
eschema = edef.e_schema
for i in range(len(rdefs)):
rtype, term, reverse = rdefs[i]
select.append_selected(term.copy(select))
if reverse:
rdefs[i] = rtype, RelationsStep.REVERSE_RELATION
else:
rschema = eschema.subjrels[rtype]
if rschema.final or rschema.inlined:
rdefs[i] = rtype, RelationsStep.FINAL
else:
rdefs[i] = rtype, RelationsStep.RELATION
if restriction is not None:
select.set_where(restriction.copy(select))
step = RelationsStep(plan, edef, rdefs)
step.children += self._select_plan(plan, select, solutions)
yield step
def build_delete_plan(self, plan, rqlst):
"""get an execution plan from a DELETE RQL query"""
# build a select query to fetch entities to delete
steps = []
for etype, var in rqlst.main_variables:
step = DeleteEntitiesStep(plan)
step.children += self._sel_variable_step(plan, rqlst.solutions,
rqlst.where, etype, var)
steps.append(step)
for relation in rqlst.main_relations:
step = DeleteRelationsStep(plan, relation.r_type)
step.children += self._sel_relation_steps(plan, rqlst.solutions,
rqlst.where, relation)
steps.append(step)
return steps
def _sel_variable_step(self, plan, solutions, restriction, etype, varref):
"""handle the selection of variables for a delete query"""
select = Select()
varref = varref.copy(select)
select.defined_vars = {varref.name: varref.variable}
select.append_selected(varref)
if restriction is not None:
select.set_where(restriction.copy(select))
if etype != 'Any':
select.add_type_restriction(varref.variable, etype)
return self._select_plan(plan, select, solutions)
def _sel_relation_steps(self, plan, solutions, restriction, relation):
"""handle the selection of relations for a delete query"""
select = Select()
lhs, rhs = relation.get_variable_parts()
select.append_selected(lhs.copy(select))
select.append_selected(rhs.copy(select))
select.set_where(relation.copy(select))
if restriction is not None:
select.add_restriction(restriction.copy(select))
return self._select_plan(plan, select, solutions)
def build_set_plan(self, plan, rqlst):
"""get an execution plan from an SET RQL query"""
select = Select()
# extract variables to add to the selection
selected_index = {}
index = 0
relations, attrrelations = [], []
getrschema = self.schema.rschema
for relation in rqlst.main_relations:
if relation.r_type in VIRTUAL_RTYPES:
raise QueryError('can not assign to %r relation'
% relation.r_type)
lhs, rhs = relation.get_variable_parts()
if not lhs.as_string('utf-8') in selected_index:
select.append_selected(lhs.copy(select))
selected_index[lhs.as_string('utf-8')] = index
index += 1
if not rhs.as_string('utf-8') in selected_index:
select.append_selected(rhs.copy(select))
selected_index[rhs.as_string('utf-8')] = index
index += 1
rschema = getrschema(relation.r_type)
if rschema.final or rschema.inlined:
attrrelations.append(relation)
else:
relations.append(relation)
# add step necessary to fetch all selected variables values
if rqlst.where is not None:
select.set_where(rqlst.where.copy(select))
# set distinct to avoid potential duplicate key error
select.distinct = True
step = UpdateStep(plan, attrrelations, relations, selected_index)
step.children += self._select_plan(plan, select, rqlst.solutions)
return (step,)
# internal methods ########################################################
def _select_plan(self, plan, select, solutions):
union = Union()
union.append(select)
select.clean_solutions(solutions)
add_types_restriction(self.schema, select)
self.rqlhelper.annotate(union)
return self.build_select_plan(plan, union)
# execution steps and helper functions ########################################
def varmap_test_repr(varmap, tablesinorder):
if varmap is None:
return varmap
maprepr = {}
for var, sql in varmap.iteritems():
table, col = sql.split('.')
maprepr[var] = '%s.%s' % (tablesinorder[table], col)
return maprepr
def offset_result(offset, result):
offset -= len(result)
if offset < 0:
result = result[offset:]
offset = None
elif offset == 0:
offset = None
result = ()
return offset, result
class LimitOffsetMixIn(object):
limit = offset = None
def set_limit_offset(self, limit, offset):
self.limit = limit
self.offset = offset or None
class Step(object):
"""base abstract class for execution step"""
def __init__(self, plan):
self.plan = plan
self.children = []
def execute_child(self):
assert len(self.children) == 1
return self.children[0].execute()
def execute_children(self):
for step in self.children:
step.execute()
def execute(self):
"""execute this step and store partial (eg this step) results"""
raise NotImplementedError()
def mytest_repr(self):
"""return a representation of this step suitable for test"""
return (self.__class__.__name__,)
def test_repr(self):
"""return a representation of this step suitable for test"""
return self.mytest_repr() + (
[step.test_repr() for step in self.children],)
class OneFetchStep(LimitOffsetMixIn, Step):
"""step consisting in fetching data from sources and directly returning
results
"""
def __init__(self, plan, union, sources, inputmap=None):
Step.__init__(self, plan)
self.union = union
self.sources = sources
self.inputmap = inputmap
self.set_limit_offset(union.children[-1].limit, union.children[-1].offset)
def set_limit_offset(self, limit, offset):
LimitOffsetMixIn.set_limit_offset(self, limit, offset)
for select in self.union.children:
select.limit = limit
select.offset = offset
def execute(self):
"""call .syntax_tree_search with the given syntax tree on each
source for each solution
"""
self.execute_children()
session = self.plan.session
args = self.plan.args
inputmap = self.inputmap
union = self.union
# do we have to use a inputmap from a previous step ? If so disable
# cachekey
if inputmap or self.plan.cache_key is None:
cachekey = None
# union may have been splited into subqueries, rebuild a cache key
elif isinstance(self.plan.cache_key, tuple):
cachekey = list(self.plan.cache_key)
cachekey[0] = union.as_string()
cachekey = tuple(cachekey)
else:
cachekey = union.as_string()
result = []
# limit / offset processing
limit = self.limit
offset = self.offset
if offset is not None:
if len(self.sources) > 1:
# we'll have to deal with limit/offset by ourself
if union.children[-1].limit:
union.children[-1].limit = limit + offset
union.children[-1].offset = None
else:
offset, limit = None, None
for source in self.sources:
if offset is None and limit is not None:
# modifying the sample rqlst is enough since sql generation
# will pick it here as well
union.children[-1].limit = limit - len(result)
result_ = source.syntax_tree_search(session, union, args, cachekey,
inputmap)
if offset is not None:
offset, result_ = offset_result(offset, result_)
result += result_
if limit is not None:
if len(result) >= limit:
return result[:limit]
#print 'ONEFETCH RESULT %s' % (result)
return result
def mytest_repr(self):
"""return a representation of this step suitable for test"""
try:
inputmap = varmap_test_repr(self.inputmap, self.plan.tablesinorder)
except AttributeError:
inputmap = self.inputmap
return (self.__class__.__name__,
sorted((r.as_string(kwargs=self.plan.args), r.solutions)
for r in self.union.children),
self.limit, self.offset,
sorted(self.sources), inputmap)
# UPDATE/INSERT/DELETE steps ##################################################
class RelationsStep(Step):
"""step consisting in adding attributes/relations to entity defs from a
previous FetchStep
relations values comes from the latest result, with one columns for
each relation defined in self.rdefs
for one entity definition, we'll construct N entity, where N is the
number of the latest result
"""
FINAL = 0
RELATION = 1
REVERSE_RELATION = 2
def __init__(self, plan, edef, rdefs):
Step.__init__(self, plan)
# partial entity definition to expand
self.edef = edef
# definition of relations to complete
self.rdefs = rdefs
def execute(self):
"""execute this step"""
base_edef = self.edef
edefs = []
result = self.execute_child()
for row in result:
# get a new entity definition for this row
edef = copy(base_edef)
# complete this entity def using row values
for i in range(len(self.rdefs)):
rtype, rorder = self.rdefs[i]
if rorder == RelationsStep.FINAL:
edef[rtype] = row[i]
elif rorder == RelationsStep.RELATION:
self.plan.add_relation_def( (edef, rtype, row[i]) )
edef.querier_pending_relations[(rtype, 'subject')] = row[i]
else:
self.plan.add_relation_def( (row[i], rtype, edef) )
edef.querier_pending_relations[(rtype, 'object')] = row[i]
edefs.append(edef)
self.plan.substitute_entity_def(base_edef, edefs)
return result
class InsertStep(Step):
"""step consisting in inserting new entities / relations"""
def execute(self):
"""execute this step"""
for step in self.children:
assert isinstance(step, RelationsStep)
step.plan = self.plan
step.execute()
# insert entities first
result = self.plan.insert_entity_defs()
# then relation
self.plan.insert_relation_defs()
# return eids of inserted entities
return result
class DeleteEntitiesStep(Step):
"""step consisting in deleting entities"""
def execute(self):
"""execute this step"""
todelete = frozenset(typed_eid(eid) for eid, in self.execute_child())
session = self.plan.session
delete = session.repo.glob_delete_entity
# register pending eids first to avoid multiple deletion
pending = session.transaction_data.setdefault('pendingeids', set())
actual = todelete - pending
pending |= actual
for eid in actual:
delete(session, eid)
class DeleteRelationsStep(Step):
"""step consisting in deleting relations"""
def __init__(self, plan, rtype):
Step.__init__(self, plan)
self.rtype = rtype
def execute(self):
"""execute this step"""
session = self.plan.session
delete = session.repo.glob_delete_relation
for subj, obj in self.execute_child():
delete(session, subj, self.rtype, obj)
class UpdateStep(Step):
"""step consisting in updating entities / adding relations from relations
definitions and from results fetched in previous step
"""
def __init__(self, plan, attribute_relations, relations, selected_index):
Step.__init__(self, plan)
self.attribute_relations = attribute_relations
self.relations = relations
self.selected_index = selected_index
def execute(self):
"""execute this step"""
plan = self.plan
session = self.plan.session
repo = session.repo
edefs = {}
# insert relations
attributes = set([relation.r_type for relation in self.attribute_relations])
result = self.execute_child()
for row in result:
for relation in self.attribute_relations:
lhs, rhs = relation.get_variable_parts()
eid = typed_eid(row[self.selected_index[str(lhs)]])
try:
edef = edefs[eid]
except KeyError:
edefs[eid] = edef = session.entity_from_eid(eid)
if isinstance(rhs, Constant):
# add constant values to entity def
value = rhs.eval(plan.args)
edef[relation.r_type] = value
else:
edef[relation.r_type] = row[self.selected_index[str(rhs)]]
for relation in self.relations:
subj = row[self.selected_index[str(relation.children[0])]]
obj = row[self.selected_index[str(relation.children[1])]]
repo.glob_add_relation(session, subj, relation.r_type, obj)
# update entities
for eid, edef in edefs.iteritems():
repo.glob_update_entity(session, edef, attributes)
return result