"""plan execution of rql queries on multiple sources
the best way to understand what are we trying to acheive here is to read the
unit-tests in unittest_msplanner.py
What you need to know
~~~~~~~~~~~~~~~~~~~~~
1. The system source is expected to support every entity and relation types
2. Given "X relation Y":
* if relation, X and Y types are supported by the external source, we suppose
by default that X and Y should both come from the same source as the
relation. You can specify otherwise by adding relation into the
"cross_relations" set in the source's mapping file and it that case, we'll
consider that we can also find in the system source some relation between
X and Y coming from different sources.
* if "relation" isn't supported by the external source but X or Y
types (or both) are, we suppose by default that can find in the system
source some relation where X and/or Y come from the external source. You
can specify otherwise by adding relation into the "dont_cross_relations"
set in the source's mapping file and it that case, we'll consider that we
can only find in the system source some relation between X and Y coming
the system source.
Implementation
~~~~~~~~~~~~~~
XXX explain algorithm
Exemples of multi-sources query execution
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For a system source and a ldap user source (only CWUser and its attributes
is supported, no group or such):
:CWUser X:
1. fetch CWUser X from both sources and return concatenation of results
:CWUser X WHERE X in_group G, G name 'users':
* catch 1
1. fetch CWUser X from both sources, store concatenation of results into a
temporary table
2. return the result of TMP X WHERE X in_group G, G name 'users' from the
system source
* catch 2
1. return the result of CWUser X WHERE X in_group G, G name 'users' from system
source, that's enough (optimization of the sql querier will avoid join on
CWUser, so we will directly get local eids)
:CWUser X,L WHERE X in_group G, X login L, G name 'users':
1. fetch Any X,L WHERE X is CWUser, X login L from both sources, store
concatenation of results into a temporary table
2. return the result of Any X, L WHERE X is TMP, X login LX in_group G,
G name 'users' from the system source
:Any X WHERE X owned_by Y:
* catch 1
1. fetch CWUser X from both sources, store concatenation of results into a
temporary table
2. return the result of Any X WHERE X owned_by Y, Y is TMP from the system
source
* catch 2
1. return the result of Any X WHERE X owned_by Y from system source, that's
enough (optimization of the sql querier will avoid join on CWUser, so we
will directly get local eids)
:organization: Logilab
:copyright: 2003-2009 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 itertools import imap, ifilterfalse
from logilab.common.compat import any
from logilab.common.decorators import cached
from rql.stmts import Union, Select
from rql.nodes import VariableRef, Comparison, Relation, Constant, Variable
from cubicweb import server
from cubicweb.utils import make_uid
from cubicweb.server.utils import cleanup_solutions
from cubicweb.server.ssplanner import (SSPlanner, OneFetchStep,
add_types_restriction)
from cubicweb.server.mssteps import *
from cubicweb.server.sources import AbstractSource
Variable._ms_table_key = lambda x: x.name
Relation._ms_table_key = lambda x: x.r_type
# str() Constant.value to ensure generated table name won't be unicode
Constant._ms_table_key = lambda x: str(x.value)
AbstractSource.dont_cross_relations = ()
AbstractSource.cross_relations = ()
def need_source_access_relation(vargraph):
if not vargraph:
return False
# check vargraph contains some other relation than the identity relation
# test of key nature since it may be a variable name (don't care about that)
# or a 2-uple (var1, var2) associated to the relation to traverse to go from
# var1 to var2
return any(key for key, val in vargraph.iteritems()
if isinstance(key, tuple) and val != 'identity')
def need_aggr_step(select, sources, stepdefs=None):
"""return True if a temporary table is necessary to store some partial
results to execute the given query
"""
if len(sources) == 1:
# can do everything at once with a single source
return False
if select.orderby or select.groupby or select.has_aggregat:
# if more than one source, we need a temp table to deal with sort /
# groups / aggregat if :
# * the rqlst won't be splitted (in the other case the last query
# using partial temporary table can do sort/groups/aggregat without
# the need for a later AggrStep)
# * the rqlst is splitted in multiple steps and there are more than one
# final step
if stepdefs is None:
return True
has_one_final = False
fstepsolindices = set()
for stepdef in stepdefs:
if stepdef[-1]:
if has_one_final or frozenset(stepdef[2]) != fstepsolindices:
return True
has_one_final = True
else:
fstepsolindices.update(stepdef[2])
return False
def select_group_sort(select): # XXX something similar done in rql2sql
# add variables used in groups and sort terms to the selection
# if necessary
if select.groupby:
for vref in select.groupby:
if not vref in select.selection:
select.append_selected(vref.copy(select))
for sortterm in select.orderby:
for vref in sortterm.iget_nodes(VariableRef):
if not vref in select.get_selected_variables():
# we can't directly insert sortterm.term because it references
# a variable of the select before the copy.
# XXX if constant term are used to define sort, their value
# may necessite a decay
select.append_selected(vref.copy(select))
if select.groupby and not vref in select.groupby:
select.add_group_var(vref.copy(select))
def allequals(solutions):
"""return true if all solutions are identical"""
sol = solutions.next()
noconstsol = None
for sol_ in solutions:
if sol_ != sol:
return False
return True
# XXX move functions below to rql ##############################################
def is_ancestor(n1, n2):
"""return True if n2 is a parent scope of n1"""
p = n1.parent
while p is not None:
if p is n2:
return True
p = p.parent
return False
def copy_node(newroot, node, subparts=()):
newnode = node.__class__(*node.initargs(newroot))
for part in subparts:
newnode.append(part)
return newnode
def used_in_outer_scope(var, scope):
"""return true if the variable is used in an outer scope of the given scope
"""
for rel in var.stinfo['relations']:
rscope = rel.scope
if not rscope is scope and is_ancestor(scope, rscope):
return True
return False
################################################################################
class PartPlanInformation(object):
"""regroups necessary information to execute some part of a "global" rql
query ("global" means as received by the querier, which may result in
several internal queries, e.g. parts, due to security insertions). Actually
a PPI is created for each subquery and for each query in a union.
It exposes as well some methods helping in executing this part on a
multi-sources repository, modifying its internal structure during the
process.
:attr plan:
the execution plan
:attr rqlst:
the original rql syntax tree handled by this part
:attr needsplit:
bool telling if the query has to be split into multiple steps for
execution or if it can be executed at once
:attr temptable:
a SQL temporary table name or None, if necessary to handle aggregate /
sorting for this part of the query
:attr finaltable:
a SQL table name or None, if results for this part of the query should be
written into a temporary table (usually shared by multiple PPI)
:attr sourcesterms:
a dictionary {source : {term: set([solution index, ])}} telling for each
source which terms are supported for which solutions. A "term" may be
either a rql Variable, Constant or Relation node.
"""
def __init__(self, plan, rqlst, rqlhelper=None):
self.plan = plan
self.rqlst = rqlst
self.needsplit = False
self.temptable = None
self.finaltable = None
# shortcuts
self._schema = plan.schema
self._session = plan.session
self._repo = self._session.repo
self._solutions = rqlst.solutions
self._solindices = range(len(self._solutions))
self.system_source = self._repo.system_source
# source : {term: [solution index, ]}
self.sourcesterms = self._sourcesterms = {}
# source : {relation: set(child variable and constant)}
self._crossrelations = {}
# dictionary of variables and constants which are linked to each other
# using a non final relation supported by multiple sources (crossed or
# not).
self._linkedterms = {}
# processing
termssources = self._compute_sourcesterms()
self._remove_invalid_sources(termssources)
self._compute_needsplit()
# after initialisation, .sourcesterms contains the same thing as
# ._sourcesterms though during plan construction, ._sourcesterms will
# be modified while .sourcesterms will be kept unmodified
self.sourcesterms = {}
for k, v in self._sourcesterms.iteritems():
self.sourcesterms[k] = {}
for k2, v2 in v.iteritems():
self.sourcesterms[k][k2] = v2.copy()
# cleanup linked var
for var, linkedrelsinfo in self._linkedterms.iteritems():
self._linkedterms[var] = frozenset(x[0] for x in linkedrelsinfo)
# map output of a step to input of a following step
self._inputmaps = {}
# record input map conflicts to resolve them on final step generation
self._conflicts = []
if rqlhelper is not None: # else test
self._insert_identity_variable = rqlhelper._annotator.rewrite_shared_optional
if server.DEBUG & server.DBG_MS:
print 'sourcesterms:'
self._debug_sourcesterms()
def _debug_sourcesterms(self):
for source in self._sourcesterms:
print '-', source
for term, sols in self._sourcesterms[source].items():
print ' -', term, id(term), ':' ,sols
def copy_solutions(self, solindices):
return [self._solutions[solidx].copy() for solidx in solindices]
@property
@cached
def part_sources(self):
if self._sourcesterms:
return tuple(sorted(self._sourcesterms))
return (self.system_source,)
@property
@cached
def _sys_source_set(self):
return frozenset((self.system_source, solindex)
for solindex in self._solindices)
@cached
def _norel_support_set(self, relation):
"""return a set of (source, solindex) where source doesn't support the
relation
"""
return frozenset((source, solidx) for source in self._repo.sources
for solidx in self._solindices
if not ((source.support_relation(relation.r_type))
or relation.r_type in source.dont_cross_relations))
def _compute_sourcesterms(self):
"""compute for each term (variable, rewritten constant, relation) and
for each solution in the rqlst which sources support them
"""
repo = self._repo
eschema = self._schema.eschema
sourcesterms = self._sourcesterms
# find for each source which variable/solution are supported
for varname, varobj in self.rqlst.defined_vars.items():
# if variable has an eid specified, we can get its source directly
# NOTE: use uidrels and not constnode to deal with "X eid IN(1,2,3,4)"
if varobj.stinfo['uidrels']:
vrels = varobj.stinfo['relations'] - varobj.stinfo['uidrels']
for rel in varobj.stinfo['uidrels']:
if rel.neged(strict=True) or rel.operator() != '=':
continue
for const in rel.children[1].get_nodes(Constant):
eid = const.eval(self.plan.args)
source = self._session.source_from_eid(eid)
if vrels and not any(source.support_relation(r.r_type)
for r in vrels):
self._set_source_for_term(self.system_source, varobj)
else:
self._set_source_for_term(source, varobj)
continue
rels = varobj.stinfo['relations']
if not rels and not varobj.stinfo['typerels']:
# (rare) case where the variable has no type specified nor
# relation accessed ex. "Any MAX(X)"
self._set_source_for_term(self.system_source, varobj)
continue
for i, sol in enumerate(self._solutions):
vartype = sol[varname]
# skip final variable
if eschema(vartype).is_final():
break
for source in repo.sources:
if source.support_entity(vartype):
# the source support the entity type, though we will
# actually have to fetch from it only if
# * the variable isn't invariant
# * at least one supported relation specified
if not varobj._q_invariant or \
any(imap(source.support_relation,
(r.r_type for r in rels if r.r_type != 'eid'))):
sourcesterms.setdefault(source, {}).setdefault(varobj, set()).add(i)
# if variable is not invariant and is used by a relation
# not supported by this source, we'll have to split the
# query
if not varobj._q_invariant and any(ifilterfalse(
source.support_relation, (r.r_type for r in rels))):
self.needsplit = True
# add source for rewritten constants to sourcesterms
for vconsts in self.rqlst.stinfo['rewritten'].itervalues():
const = vconsts[0]
source = self._session.source_from_eid(const.eval(self.plan.args))
if source is self.system_source:
for const in vconsts:
self._set_source_for_term(source, const)
elif not self._sourcesterms:
self._set_source_for_term(source, const)
elif source in self._sourcesterms:
source_scopes = frozenset(t.scope for t in self._sourcesterms[source])
for const in vconsts:
if const.scope in source_scopes:
self._set_source_for_term(source, const)
# if system source is used, add every rewritten constant
# to its supported terms even when associated entity
# doesn't actually come from it so we get a changes
# that allequals will return True as expected when
# computing needsplit
# check const is used in a relation restriction
if const.relation() and self.system_source in sourcesterms:
self._set_source_for_term(self.system_source, const)
# add source for relations
rschema = self._schema.rschema
termssources = {}
for rel in self.rqlst.iget_nodes(Relation):
# process non final relations only
# note: don't try to get schema for 'is' relation (not available
# during bootstrap)
if not rel.is_types_restriction() and not rschema(rel.r_type).is_final():
# nothing to do if relation is not supported by multiple sources
# or if some source has it listed in its cross_relations
# attribute
#
# XXX code below don't deal if some source allow relation
# crossing but not another one
relsources = repo.rel_type_sources(rel.r_type)
if len(relsources) < 2:
# filter out sources being there because they have this
# relation in their dont_cross_relations attribute
relsources = [source for source in relsources
if source.support_relation(rel.r_type)]
if relsources:
# this means the relation is using a variable inlined as
# a constant and another unsupported variable, in which
# case we put the relation in sourcesterms
self._sourcesterms.setdefault(relsources[0], {})[rel] = set(self._solindices)
continue
lhs, rhs = rel.get_variable_parts()
lhsv, rhsv = getattr(lhs, 'variable', lhs), getattr(rhs, 'variable', rhs)
# update dictionary of sources supporting lhs and rhs vars
if not lhsv in termssources:
termssources[lhsv] = self._term_sources(lhs)
if not rhsv in termssources:
termssources[rhsv] = self._term_sources(rhs)
self._handle_cross_relation(rel, relsources, termssources)
self._linkedterms.setdefault(lhsv, set()).add((rhsv, rel))
self._linkedterms.setdefault(rhsv, set()).add((lhsv, rel))
return termssources
def _handle_cross_relation(self, rel, relsources, termssources):
for source in relsources:
if rel.r_type in source.cross_relations:
ssource = self.system_source
crossvars = set(x.variable for x in rel.get_nodes(VariableRef))
for const in rel.get_nodes(Constant):
if source.uri != 'system' and not const in self._sourcesterms.get(source, ()):
continue
crossvars.add(const)
self._crossrelations.setdefault(source, {})[rel] = crossvars
if len(crossvars) < 2:
# this means there is a constant in the relation which is
# not supported by the source, so we can stop here
continue
self._sourcesterms.setdefault(ssource, {})[rel] = set(self._solindices)
for term in crossvars:
if len(termssources[term]) == 1 and iter(termssources[term]).next()[0].uri == 'system':
for ov in crossvars:
if ov is not term and (isinstance(ov, Constant) or ov._q_invariant):
ssset = frozenset((ssource,))
self._remove_sources(ov, termssources[ov] - ssset)
break
else:
self._sourcesterms.setdefault(source, {})[rel] = set(self._solindices)
def _remove_invalid_sources(self, termssources):
"""removes invalid sources from `sourcesterms` member according to
traversed relations and their properties (which sources support them,
can they cross sources, etc...)
"""
for term in self._linkedterms:
self._remove_sources_until_stable(term, termssources)
if len(self._sourcesterms) > 1 and hasattr(self.plan.rqlst, 'main_relations'):
# the querier doesn't annotate write queries, need to do it here
self.plan.annotate_rqlst()
# insert/update/delete queries, we may get extra information from
# the main relation (eg relations to the left of the WHERE
if self.plan.rqlst.TYPE == 'insert':
inserted = dict((vref.variable, etype)
for etype, vref in self.plan.rqlst.main_variables)
else:
inserted = {}
repo = self._repo
rschema = self._schema.rschema
for rel in self.plan.rqlst.main_relations:
if not rschema(rel.r_type).is_final():
# nothing to do if relation is not supported by multiple sources
if len(repo.rel_type_sources(rel.r_type)) < 2:
continue
lhs, rhs = rel.get_variable_parts()
try:
lhsv = self._extern_term(lhs, termssources, inserted)
rhsv = self._extern_term(rhs, termssources, inserted)
except KeyError, ex:
continue
self._remove_term_sources(lhsv, rel, rhsv, termssources)
self._remove_term_sources(rhsv, rel, lhsv, termssources)
def _extern_term(self, term, termssources, inserted):
var = term.variable
if var.stinfo['constnode']:
termv = var.stinfo['constnode']
termssources[termv] = self._term_sources(termv)
elif var in inserted:
termv = var
source = self._repo.locate_etype_source(inserted[var])
termssources[termv] = set((source, solindex)
for solindex in self._solindices)
else:
termv = self.rqlst.defined_vars[var.name]
if not termv in termssources:
termssources[termv] = self._term_sources(termv)
return termv
def _remove_sources_until_stable(self, term, termssources):
sourcesterms = self._sourcesterms
for oterm, rel in self._linkedterms.get(term, ()):
if not term.scope is oterm.scope and rel.scope.neged(strict=True):
# can't get information from relation inside a NOT exists
# where terms don't belong to the same scope
continue
need_ancestor_scope = False
if not (term.scope is rel.scope and oterm.scope is rel.scope):
if rel.ored():
continue
if rel.ored(traverse_scope=True):
# if relation has some OR as parent, constraints should only
# propagate from parent scope to child scope, nothing else
need_ancestor_scope = True
relsources = self._repo.rel_type_sources(rel.r_type)
if rel.neged(strict=True) and (
len(relsources) < 2
or not isinstance(oterm, Variable)
or oterm.valuable_references() != 1
or any(sourcesterms[source][term] != sourcesterms[source][oterm]
for source in relsources
if term in sourcesterms.get(source, ())
and oterm in sourcesterms.get(source, ()))):
# neged relation doesn't allow to infer term sources unless
# we're on a multisource relation for a term only used by this
# relation (eg "Any X WHERE NOT X multisource_rel Y" and over is
# Y)
continue
# compute invalid sources for terms and remove them
if not need_ancestor_scope or is_ancestor(term.scope, oterm.scope):
self._remove_term_sources(term, rel, oterm, termssources)
if not need_ancestor_scope or is_ancestor(oterm.scope, term.scope):
self._remove_term_sources(oterm, rel, term, termssources)
def _remove_term_sources(self, term, rel, oterm, termssources):
"""remove invalid sources for term according to oterm's sources and the
relation between those two terms.
"""
norelsup = self._norel_support_set(rel)
termsources = termssources[term]
invalid_sources = termsources - (termssources[oterm] | norelsup)
if invalid_sources and self._repo.can_cross_relation(rel.r_type):
invalid_sources -= self._sys_source_set
if invalid_sources and isinstance(term, Variable) \
and self._need_ext_source_access(term, rel):
# if the term is a not invariant variable, we should filter out
# source where the relation is a cross relation from invalid
# sources
invalid_sources = frozenset((s, solidx) for s, solidx in invalid_sources
if not (s in self._crossrelations and
rel in self._crossrelations[s]))
if invalid_sources:
self._remove_sources(term, invalid_sources)
termsources -= invalid_sources
self._remove_sources_until_stable(term, termssources)
if isinstance(oterm, Constant):
self._remove_sources(oterm, invalid_sources)
def _compute_needsplit(self):
"""tell according to sourcesterms if the rqlst has to be splitted for
execution among multiple sources
the execution has to be split if
* a source support an entity (non invariant) but doesn't support a
relation on it
* a source support an entity which is accessed by an optional relation
* there is more than one source and either all sources'supported
variable/solutions are not equivalent or multiple variables have to
be fetched from some source
"""
# NOTE: < 2 since may be 0 on queries such as Any X WHERE X eid 2
if len(self._sourcesterms) < 2:
self.needsplit = False
# if this is not the system source but we have only constant terms
# and no relation (other than eid), apply query on the system source
#
# testing for rqlst with nothing in vargraph nor defined_vars is the
# simplest way the check the condition explained below
if not self.system_source in self._sourcesterms and \
not self.rqlst.defined_vars and \
not need_source_access_relation(self.rqlst.vargraph):
self._sourcesterms = {self.system_source: {}}
elif not self.needsplit:
if not allequals(self._sourcesterms.itervalues()):
for source, terms in self._sourcesterms.iteritems():
if source is self.system_source:
continue
if any(x for x in terms if not isinstance(x, Constant)):
self.needsplit = True
return
self._sourcesterms = {self.system_source: {}}
self.needsplit = False
else:
sample = self._sourcesterms.itervalues().next()
if len(sample) > 1:
for term in sample:
# need split if unlinked variable
if isinstance(term, Variable) and not term in self._linkedterms:
self.needsplit = True
break
else:
# need split if there are some cross relation on non
# invariant variable or if the variable is used in
# multi-sources relation
if self._crossrelations:
for reldict in self._crossrelations.itervalues():
for rel, terms in reldict.iteritems():
for term in terms:
if isinstance(term, Variable) \
and self._need_ext_source_access(term, rel):
self.needsplit = True
return
@cached
def _need_ext_source_access(self, var, rel):
if not var._q_invariant:
return True
if any(r for x, r in self._linkedterms[var]
if not r is rel and self._repo.is_multi_sources_relation(r.r_type)):
return True
return False
def _set_source_for_term(self, source, term):
self._sourcesterms.setdefault(source, {})[term] = set(self._solindices)
def _term_sources(self, term):
"""returns possible sources for terms `term`"""
if isinstance(term, Constant):
source = self._session.source_from_eid(term.eval(self.plan.args))
return set((source, solindex) for solindex in self._solindices)
else:
var = getattr(term, 'variable', term)
sources = [source for source, varobjs in self.sourcesterms.iteritems()
if var in varobjs]
return set((source, solindex) for source in sources
for solindex in self.sourcesterms[source][var])
def _remove_sources(self, term, sources):
"""removes invalid sources (`sources`) from `sourcesterms`
:param sources: the list of sources to remove
:param term: the analyzed term
"""
sourcesterms = self._sourcesterms
for source, solindex in sources:
try:
sourcesterms[source][term].remove(solindex)
except KeyError:
import rql.base as rqlb
assert isinstance(term, rqlb.BaseNode), repr(term)
continue # may occur with subquery column alias
if not sourcesterms[source][term]:
del sourcesterms[source][term]
if not sourcesterms[source]:
del sourcesterms[source]
def crossed_relation(self, source, relation):
return relation in self._crossrelations.get(source, ())
def part_steps(self):
"""precompute necessary part steps before generating actual rql for
each step. This is necessary to know if an aggregate step will be
necessary or not.
"""
steps = []
select = self.rqlst
rschema = self._schema.rschema
for source in self.part_sources:
try:
sourceterms = self._sourcesterms[source]
except KeyError:
continue # already proceed
while sourceterms:
# take a term randomly, and all terms supporting the
# same solutions
term, solindices = self._choose_term(sourceterms)
if source.uri == 'system':
# ensure all variables are available for the latest step
# (missing one will be available from temporary tables
# of previous steps)
scope = select
terms = scope.defined_vars.values() + scope.aliases.values()
sourceterms.clear()
sources = [source]
else:
scope = term.scope
# find which sources support the same term and solutions
sources = self._expand_sources(source, term, solindices)
# no try to get as much terms as possible
terms = self._expand_terms(term, sources, sourceterms,
scope, solindices)
if len(terms) == 1 and isinstance(terms[0], Constant):
# we can't generate anything interesting with a single
# constant term (will generate an empty "Any" query),
# go to the next iteration directly!
continue
if not sourceterms:
try:
del self._sourcesterms[source]
except KeyError:
# XXX already cleaned
pass
# set of terms which should be additionaly selected when
# possible
needsel = set()
if not self._sourcesterms:
terms += scope.defined_vars.values() + scope.aliases.values()
final = True
else:
# suppose this is a final step until the contrary is proven
final = scope is select
# add attribute variables and mark variables which should be
# additionaly selected when possible
for var in select.defined_vars.itervalues():
if not var in terms:
stinfo = var.stinfo
for ovar, rtype in stinfo['attrvars']:
if ovar in terms:
needsel.add(var.name)
terms.append(var)
break
else:
needsel.add(var.name)
final = False
# check where all relations are supported by the sources
for rel in scope.iget_nodes(Relation):
if rel.is_types_restriction():
continue
# take care not overwriting the existing "source" identifier
for _source in sources:
if not _source.support_relation(rel.r_type) or (
self.crossed_relation(_source, rel) and not rel in terms):
for vref in rel.iget_nodes(VariableRef):
needsel.add(vref.name)
final = False
break
else:
if not scope is select:
self._exists_relation(rel, terms, needsel)
# if relation is supported by all sources and some of
# its lhs/rhs variable isn't in "terms", and the
# other end *is* in "terms", mark it have to be
# selected
if source.uri != 'system' and not rschema(rel.r_type).is_final():
lhs, rhs = rel.get_variable_parts()
try:
lhsvar = lhs.variable
except AttributeError:
lhsvar = lhs
try:
rhsvar = rhs.variable
except AttributeError:
rhsvar = rhs
if lhsvar in terms and not rhsvar in terms:
needsel.add(lhsvar.name)
elif rhsvar in terms and not lhsvar in terms:
needsel.add(rhsvar.name)
if final and source.uri != 'system':
# check rewritten constants
for vconsts in select.stinfo['rewritten'].itervalues():
const = vconsts[0]
eid = const.eval(self.plan.args)
_source = self._session.source_from_eid(eid)
if len(sources) > 1 or not _source in sources:
# if there is some rewriten constant used by a not
# neged relation while there are some source not
# supporting the associated entity, this step can't
# be final (unless the relation is explicitly in
# `terms`, eg cross relations)
for c in vconsts:
rel = c.relation()
if rel is None or not (rel in terms or rel.neged(strict=True)):
final = False
break
break
if final:
self._cleanup_sourcesterms(sources, solindices)
steps.append((sources, terms, solindices, scope, needsel, final)
)
return steps
def _exists_relation(self, rel, terms, needsel):
rschema = self._schema.rschema(rel.r_type)
lhs, rhs = rel.get_variable_parts()
try:
lhsvar, rhsvar = lhs.variable, rhs.variable
except AttributeError:
pass
else:
# supported relation with at least one end supported, check the
# other end is in as well. If not this usually means the
# variable is refed by an outer scope and should be substituted
# using an 'identity' relation (else we'll get a conflict of
# temporary tables)
if rhsvar in terms and not lhsvar in terms:
self._identity_substitute(rel, lhsvar, terms, needsel)
elif lhsvar in terms and not rhsvar in terms:
self._identity_substitute(rel, rhsvar, terms, needsel)
def _identity_substitute(self, relation, var, terms, needsel):
newvar = self._insert_identity_variable(relation.scope, var)
if newvar is not None:
# ensure relation is using '=' operator, else we rely on a
# sqlgenerator side effect (it won't insert an inequality operator
# in this case)
relation.children[1].operator = '='
terms.append(newvar)
needsel.add(newvar.name)
def _choose_term(self, sourceterms):
"""pick one term among terms supported by a source, which will be used
as a base to generate an execution step
"""
secondchoice = None
if len(self._sourcesterms) > 1:
# priority to variable from subscopes
for term in sourceterms:
if not term.scope is self.rqlst:
if isinstance(term, Variable):
return term, sourceterms.pop(term)
secondchoice = term
else:
# priority to variable from outer scope
for term in sourceterms:
if term.scope is self.rqlst:
if isinstance(term, Variable):
return term, sourceterms.pop(term)
secondchoice = term
if secondchoice is not None:
return secondchoice, sourceterms.pop(secondchoice)
# priority to variable with the less solutions supported and with the
# most valuable refs. Add variable name for test predictability
variables = sorted([(var, sols) for (var, sols) in sourceterms.items()
if isinstance(var, Variable)],
key=lambda (v, s): (len(s), -v.valuable_references(), v.name))
if variables:
var = variables[0][0]
return var, sourceterms.pop(var)
# priority to constant
for term in sourceterms:
if isinstance(term, Constant):
return term, sourceterms.pop(term)
# whatever (relation)
term = iter(sourceterms).next()
return term, sourceterms.pop(term)
def _expand_sources(self, selected_source, term, solindices):
"""return all sources supporting given term / solindices"""
sources = [selected_source]
sourcesterms = self._sourcesterms
for source in sourcesterms.keys():
if source is selected_source:
continue
if not (term in sourcesterms[source] and
solindices.issubset(sourcesterms[source][term])):
continue
sources.append(source)
if source.uri != 'system' or not (isinstance(term, Variable) and not term in self._linkedterms):
termsolindices = sourcesterms[source][term]
termsolindices -= solindices
if not termsolindices:
del sourcesterms[source][term]
if not sourcesterms[source]:
del sourcesterms[source]
return sources
def _expand_terms(self, term, sources, sourceterms, scope, solindices):
terms = [term]
sources = sorted(sources)
sourcesterms = self._sourcesterms
nbunlinked = 1
linkedterms = self._linkedterms
# term has to belong to the same scope if there is more
# than the system source remaining
if len(sourcesterms) > 1 and not scope is self.rqlst:
candidates = (t for t in sourceterms.keys() if scope is t.scope)
else:
candidates = sourceterms #.iterkeys()
# we only want one unlinked term in each generated query
candidates = [t for t in candidates
if isinstance(t, (Constant, Relation)) or
(solindices.issubset(sourceterms[t]) and t in linkedterms)]
cross_rels = {}
for source in sources:
cross_rels.update(self._crossrelations.get(source, {}))
exclude = {}
for rel, crossvars in cross_rels.iteritems():
vars = [t for t in crossvars if isinstance(t, Variable)]
try:
exclude[vars[0]] = vars[1]
exclude[vars[1]] = vars[0]
except IndexError:
pass
accept_term = lambda x: (not any(s for s in sources if not x in sourcesterms.get(s, ()))
and any(t for t in terms if t in linkedterms.get(x, ()))
and not exclude.get(x) in terms)
if isinstance(term, Relation) and term in cross_rels:
cross_terms = cross_rels.pop(term)
base_accept_term = accept_term
accept_term = lambda x: (base_accept_term(x) or x in cross_terms)
for refed in cross_terms:
if not refed in candidates:
terms.append(refed)
# repeat until no term can't be added, since addition of a new
# term may permit to another one to be added
modified = True
while modified and candidates:
modified = False
for term in candidates[:]:
if isinstance(term, Constant):
relation = term.relation()
if sorted(set(x[0] for x in self._term_sources(term))) != sources:
continue
terms.append(term)
candidates.remove(term)
modified = True
del sourceterms[term]
elif accept_term(term):
terms.append(term)
candidates.remove(term)
modified = True
self._cleanup_sourcesterms(sources, solindices, term)
return terms
def _cleanup_sourcesterms(self, sources, solindices, term=None):
"""remove solutions so we know they are already processed"""
for source in sources:
try:
sourceterms = self._sourcesterms[source]
except KeyError:
continue
if term is None:
for term, termsolindices in sourceterms.items():
if isinstance(term, Relation) and self.crossed_relation(source, term):
continue
termsolindices -= solindices
if not termsolindices:
del sourceterms[term]
else:
try:
sourceterms[term] -= solindices
if not sourceterms[term]:
del sourceterms[term]
except KeyError:
pass
#assert term in cross_terms
if not sourceterms:
del self._sourcesterms[source]
def merge_input_maps(self, allsolindices):
"""inputmaps is a dictionary with tuple of solution indices as key with
an associated input map as value. This function compute for each
solution its necessary input map and return them grouped
ex:
inputmaps = {(0, 1, 2): {'A': 't1.login1', 'U': 't1.C0', 'U.login': 't1.login1'},
(1,): {'X': 't2.C0', 'T': 't2.C1'}}
return : [([1], {'A': 't1.login1', 'U': 't1.C0', 'U.login': 't1.login1',
'X': 't2.C0', 'T': 't2.C1'}),
([0,2], {'A': 't1.login1', 'U': 't1.C0', 'U.login': 't1.login1'})]
"""
if not self._inputmaps:
return [(allsolindices, None)]
mapbysol = {}
# compute a single map for each solution
for solindices, basemap in self._inputmaps.iteritems():
for solindex in solindices:
solmap = mapbysol.setdefault(solindex, {})
solmap.update(basemap)
try:
allsolindices.remove(solindex)
except KeyError:
continue # already removed
# group results by identical input map
result = []
for solindex, solmap in mapbysol.iteritems():
for solindices, commonmap in result:
if commonmap == solmap:
solindices.append(solindex)
break
else:
result.append( ([solindex], solmap) )
if allsolindices:
result.append( (list(allsolindices), None) )
return result
def build_final_part(self, select, solindices, inputmap, sources,
insertedvars):
solutions = [self._solutions[i] for i in solindices]
if self._conflicts:
for varname, mappedto in self._conflicts:
var = select.defined_vars[varname]
newvar = select.make_variable()
# XXX should use var.scope but scope hasn't been computed yet
select.add_relation(var, 'identity', newvar)
for sol in solutions:
sol[newvar.name] = sol[varname]
inputmap[newvar.name] = mappedto
rqlst = self.plan.finalize(select, solutions, insertedvars)
if self.temptable is None and self.finaltable is None:
return OneFetchStep(self.plan, rqlst, sources, inputmap=inputmap)
table = self.temptable or self.finaltable
return FetchStep(self.plan, rqlst, sources, table, True, inputmap)
def build_non_final_part(self, select, solindices, sources, insertedvars,
table):
"""non final step, will have to store results in a temporary table"""
solutions = [self._solutions[i] for i in solindices]
rqlst = self.plan.finalize(select, solutions, insertedvars)
step = FetchStep(self.plan, rqlst, sources, table, False)
# update input map for following steps, according to processed solutions
inputmapkey = tuple(sorted(solindices))
inputmap = self._inputmaps.setdefault(inputmapkey, {})
for varname, mapping in step.outputmap.iteritems():
if varname in inputmap and \
not (mapping == inputmap[varname] or
self._schema.eschema(solutions[0][varname]).is_final()):
self._conflicts.append((varname, inputmap[varname]))
inputmap.update(step.outputmap)
self.plan.add_step(step)
class MSPlanner(SSPlanner):
"""MultiSourcesPlanner: build execution plan for rql queries
decompose the RQL query according to sources'schema
"""
def build_select_plan(self, plan, rqlst):
"""build execution plan for a SELECT RQL query
the rqlst should not be tagged at this point
"""
if server.DEBUG & server.DBG_MS:
print '-'*80
print 'PLANNING', rqlst
for select in rqlst.children:
if len(select.solutions) > 1:
hasmultiplesols = True
break
else:
hasmultiplesols = False
# preprocess deals with security insertion and returns a new syntax tree
# which have to be executed to fulfill the query: according
# to permissions for variable's type, different rql queries may have to
# be executed
plan.preprocess(rqlst)
ppis = [PartPlanInformation(plan, select, self.rqlhelper)
for select in rqlst.children]
steps = self._union_plan(plan, rqlst, ppis)
if server.DEBUG & server.DBG_MS:
from pprint import pprint
for step in plan.steps:
pprint(step.test_repr())
pprint(steps[0].test_repr())
return steps
def _ppi_subqueries(self, ppi):
# part plan info for subqueries
plan = ppi.plan
inputmap = {}
for subquery in ppi.rqlst.with_[:]:
sppis = [PartPlanInformation(plan, select)
for select in subquery.query.children]
for sppi in sppis:
if sppi.needsplit or sppi.part_sources != ppi.part_sources:
temptable = 'T%s' % make_uid(id(subquery))
sstep = self._union_plan(plan, subquery.query, sppis, temptable)[0]
break
else:
sstep = None
if sstep is not None:
ppi.rqlst.with_.remove(subquery)
for i, colalias in enumerate(subquery.aliases):
inputmap[colalias.name] = '%s.C%s' % (temptable, i)
ppi.plan.add_step(sstep)
return inputmap
def _union_plan(self, plan, union, ppis, temptable=None):
tosplit, cango, allsources = [], {}, set()
for planinfo in ppis:
if planinfo.needsplit:
tosplit.append(planinfo)
else:
cango.setdefault(planinfo.part_sources, []).append(planinfo)
for source in planinfo.part_sources:
allsources.add(source)
# first add steps for query parts which doesn't need to splitted
steps = []
for sources, cppis in cango.iteritems():
byinputmap = {}
for ppi in cppis:
select = ppi.rqlst
if sources != (ppi.system_source,):
add_types_restriction(self.schema, select)
# part plan info for subqueries
inputmap = self._ppi_subqueries(ppi)
aggrstep = need_aggr_step(select, sources)
if aggrstep:
atemptable = 'T%s' % make_uid(id(select))
sunion = Union()
sunion.append(select)
selected = select.selection[:]
select_group_sort(select)
step = AggrStep(plan, selected, select, atemptable, temptable)
step.set_limit_offset(select.limit, select.offset)
select.limit = None
select.offset = 0
fstep = FetchStep(plan, sunion, sources, atemptable, True, inputmap)
step.children.append(fstep)
steps.append(step)
else:
byinputmap.setdefault(tuple(inputmap.iteritems()), []).append( (select) )
for inputmap, queries in byinputmap.iteritems():
inputmap = dict(inputmap)
sunion = Union()
for select in queries:
sunion.append(select)
if temptable:
steps.append(FetchStep(plan, sunion, sources, temptable, True, inputmap))
else:
steps.append(OneFetchStep(plan, sunion, sources, inputmap))
# then add steps for splitted query parts
for planinfo in tosplit:
steps.append(self.split_part(planinfo, temptable))
if len(steps) > 1:
if temptable:
step = UnionFetchStep(plan)
else:
step = UnionStep(plan)
step.children = steps
return (step,)
return steps
# internal methods for multisources decomposition #########################
def split_part(self, ppi, temptable):
ppi.finaltable = temptable
plan = ppi.plan
select = ppi.rqlst
subinputmap = self._ppi_subqueries(ppi)
stepdefs = ppi.part_steps()
if need_aggr_step(select, ppi.part_sources, stepdefs):
atemptable = 'T%s' % make_uid(id(select))
selection = select.selection[:]
select_group_sort(select)
else:
atemptable = None
selection = select.selection
ppi.temptable = atemptable
vfilter = TermsFiltererVisitor(self.schema, ppi)
steps = []
for sources, terms, solindices, scope, needsel, final in stepdefs:
# extract an executable query using only the specified terms
if sources[0].uri == 'system':
# in this case we have to merge input maps before call to
# filter so already processed restriction are correctly
# removed
solsinputmaps = ppi.merge_input_maps(solindices)
for solindices, inputmap in solsinputmaps:
minrqlst, insertedvars = vfilter.filter(
sources, terms, scope, set(solindices), needsel, final)
if inputmap is None:
inputmap = subinputmap
else:
inputmap.update(subinputmap)
steps.append(ppi.build_final_part(minrqlst, solindices, inputmap,
sources, insertedvars))
else:
# this is a final part (i.e. retreiving results for the
# original query part) if all term / sources have been
# treated or if this is the last shot for used solutions
minrqlst, insertedvars = vfilter.filter(
sources, terms, scope, solindices, needsel, final)
if final:
solsinputmaps = ppi.merge_input_maps(solindices)
for solindices, inputmap in solsinputmaps:
if inputmap is None:
inputmap = subinputmap
else:
inputmap.update(subinputmap)
if inputmap and len(sources) > 1:
sources.remove(ppi.system_source)
steps.append(ppi.build_final_part(minrqlst, solindices, None,
sources, insertedvars))
steps.append(ppi.build_final_part(minrqlst, solindices, inputmap,
[ppi.system_source], insertedvars))
else:
steps.append(ppi.build_final_part(minrqlst, solindices, inputmap,
sources, insertedvars))
else:
table = '_T%s%s' % (''.join(sorted(v._ms_table_key() for v in terms)),
''.join(sorted(str(i) for i in solindices)))
ppi.build_non_final_part(minrqlst, solindices, sources,
insertedvars, table)
# finally: join parts, deal with aggregat/group/sorts if necessary
if atemptable is not None:
step = AggrStep(plan, selection, select, atemptable, temptable)
step.children = steps
elif len(steps) > 1:
if select.need_intersect or any(select.need_intersect
for step in steps
for select in step.union.children):
if temptable:
step = IntersectFetchStep(plan)
else:
step = IntersectStep(plan)
else:
if temptable:
step = UnionFetchStep(plan)
else:
step = UnionStep(plan)
step.children = steps
else:
step = steps[0]
if select.limit is not None or select.offset:
step.set_limit_offset(select.limit, select.offset)
return step
class UnsupportedBranch(Exception):
pass
class TermsFiltererVisitor(object):
def __init__(self, schema, ppi):
self.schema = schema
self.ppi = ppi
self.skip = {}
self.hasaggrstep = self.ppi.temptable
self.extneedsel = frozenset(vref.name for sortterm in ppi.rqlst.orderby
for vref in sortterm.iget_nodes(VariableRef))
def _rqlst_accept(self, rqlst, node, newroot, terms, setfunc=None):
try:
newrestr, node_ = node.accept(self, newroot, terms[:])
except UnsupportedBranch:
return rqlst
if setfunc is not None and newrestr is not None:
setfunc(newrestr)
if not node_ is node:
rqlst = node.parent
return rqlst
def filter(self, sources, terms, rqlst, solindices, needsel, final):
if server.DEBUG & server.DBG_MS:
print 'filter', final and 'final' or '', sources, terms, rqlst, solindices, needsel
newroot = Select()
self.sources = sorted(sources)
self.terms = terms
self.solindices = solindices
self.final = final
self._pending_vrefs = []
# terms which appear in unsupported branches
needsel |= self.extneedsel
self.needsel = needsel
# terms which appear in supported branches
self.mayneedsel = set()
# new inserted variables
self.insertedvars = []
# other structures (XXX document)
self.mayneedvar, self.hasvar = {}, {}
self.use_only_defined = False
self.scopes = {rqlst: newroot}
self.current_scope = rqlst
if rqlst.where:
rqlst = self._rqlst_accept(rqlst, rqlst.where, newroot, terms,
newroot.set_where)
if isinstance(rqlst, Select):
self.use_only_defined = True
if rqlst.groupby:
groupby = []
for node in rqlst.groupby:
rqlst = self._rqlst_accept(rqlst, node, newroot, terms,
groupby.append)
if groupby:
newroot.set_groupby(groupby)
if rqlst.having:
having = []
for node in rqlst.having:
rqlst = self._rqlst_accept(rqlst, node, newroot, terms,
having.append)
if having:
newroot.set_having(having)
if final and rqlst.orderby and not self.hasaggrstep:
orderby = []
for node in rqlst.orderby:
rqlst = self._rqlst_accept(rqlst, node, newroot, terms,
orderby.append)
if orderby:
newroot.set_orderby(orderby)
self.process_selection(newroot, terms, rqlst)
elif not newroot.where:
# no restrictions have been copied, just select terms and add
# type restriction (done later by add_types_restriction)
for v in terms:
if not isinstance(v, Variable):
continue
newroot.append_selected(VariableRef(newroot.get_variable(v.name)))
solutions = self.ppi.copy_solutions(solindices)
cleanup_solutions(newroot, solutions)
newroot.set_possible_types(solutions)
if final:
if self.hasaggrstep:
self.add_necessary_selection(newroot, self.mayneedsel & self.extneedsel)
newroot.distinct = rqlst.distinct
else:
self.add_necessary_selection(newroot, self.mayneedsel & self.needsel)
# insert vars to fetch constant values when needed
for (varname, rschema), reldefs in self.mayneedvar.iteritems():
for rel, ored in reldefs:
if not (varname, rschema) in self.hasvar:
self.hasvar[(varname, rschema)] = None # just to avoid further insertion
cvar = newroot.make_variable()
for sol in newroot.solutions:
sol[cvar.name] = rschema.objects(sol[varname])[0]
# if the current restriction is not used in a OR branch,
# we can keep it, else we have to drop the constant
# restriction (or we may miss some results)
if not ored:
rel = rel.copy(newroot)
newroot.add_restriction(rel)
# add a relation to link the variable
newroot.remove_node(rel.children[1])
cmp = Comparison('=')
rel.append(cmp)
cmp.append(VariableRef(cvar))
self.insertedvars.append((varname, rschema, cvar.name))
newroot.append_selected(VariableRef(newroot.get_variable(cvar.name)))
# NOTE: even if the restriction is done by this query, we have
# to let it in the original rqlst so that it appears anyway in
# the "final" query, else we may change the meaning of the query
# if there are NOT somewhere :
# 'NOT X relation Y, Y name "toto"' means X WHERE X isn't related
# to Y whose name is toto while
# 'NOT X relation Y' means X WHERE X has no 'relation' (whatever Y)
elif ored:
newroot.remove_node(rel)
add_types_restriction(self.schema, rqlst, newroot, solutions)
if server.DEBUG & server.DBG_MS:
print '--->', newroot
return newroot, self.insertedvars
def visit_and(self, node, newroot, terms):
subparts = []
for i in xrange(len(node.children)):
child = node.children[i]
try:
newchild, child_ = child.accept(self, newroot, terms)
if not child_ is child:
node = child_.parent
if newchild is None:
continue
subparts.append(newchild)
except UnsupportedBranch:
continue
if not subparts:
return None, node
if len(subparts) == 1:
return subparts[0], node
return copy_node(newroot, node, subparts), node
visit_or = visit_and
def _relation_supported(self, relation):
rtype = relation.r_type
for source in self.sources:
if not source.support_relation(rtype) or (
rtype in source.cross_relations and not relation in self.terms):
return False
if not self.final and not relation in self.terms:
rschema = self.schema.rschema(relation.r_type)
if not rschema.is_final():
for term in relation.get_nodes((VariableRef, Constant)):
term = getattr(term, 'variable', term)
termsources = sorted(set(x[0] for x in self.ppi._term_sources(term)))
if termsources and termsources != self.sources:
return False
return True
def visit_relation(self, node, newroot, terms):
if not node.is_types_restriction():
if node in self.skip and self.solindices.issubset(self.skip[node]):
if not self.schema.rschema(node.r_type).is_final():
# can't really skip the relation if one variable is selected and only
# referenced by this relation
for vref in node.iget_nodes(VariableRef):
stinfo = vref.variable.stinfo
if stinfo['selected'] and len(stinfo['relations']) == 1:
break
else:
return None, node
else:
return None, node
if not self._relation_supported(node):
raise UnsupportedBranch()
# don't copy type restriction unless this is the only relation for the
# rhs variable, else they'll be reinserted later as needed (else we may
# copy a type restriction while the variable is not actually used)
elif not any(self._relation_supported(rel)
for rel in node.children[0].variable.stinfo['relations']):
rel, node = self.visit_default(node, newroot, terms)
return rel, node
else:
raise UnsupportedBranch()
rschema = self.schema.rschema(node.r_type)
self._pending_vrefs = []
try:
res = self.visit_default(node, newroot, terms)[0]
except:
# when a relation isn't supported, we should dereference potentially
# introduced variable refs
for vref in self._pending_vrefs:
vref.unregister_reference()
raise
ored = node.ored()
if rschema.is_final() or rschema.inlined:
vrefs = node.children[1].get_nodes(VariableRef)
if not vrefs:
if not ored:
self.skip.setdefault(node, set()).update(self.solindices)
else:
self.mayneedvar.setdefault((node.children[0].name, rschema), []).append( (res, ored) )
else:
assert len(vrefs) == 1
vref = vrefs[0]
# XXX check operator ?
self.hasvar[(node.children[0].name, rschema)] = vref
if self._may_skip_attr_rel(rschema, node, vref, ored, terms, res):
self.skip.setdefault(node, set()).update(self.solindices)
elif not ored:
self.skip.setdefault(node, set()).update(self.solindices)
return res, node
def _may_skip_attr_rel(self, rschema, rel, vref, ored, terms, res):
var = vref.variable
if ored:
return False
if var.name in self.extneedsel or var.stinfo['selected']:
return False
if not var in terms or used_in_outer_scope(var, self.current_scope):
return False
if any(v for v, _ in var.stinfo['attrvars'] if not v in terms):
return False
return True
def visit_exists(self, node, newroot, terms):
newexists = node.__class__()
self.scopes = {node: newexists}
subparts, node = self._visit_children(node, newroot, terms)
if not subparts:
return None, node
newexists.set_where(subparts[0])
return newexists, node
def visit_not(self, node, newroot, terms):
subparts, node = self._visit_children(node, newroot, terms)
if not subparts:
return None, node
return copy_node(newroot, node, subparts), node
def visit_group(self, node, newroot, terms):
if not self.final:
return None, node
return self.visit_default(node, newroot, terms)
def visit_variableref(self, node, newroot, terms):
if self.use_only_defined:
if not node.variable.name in newroot.defined_vars:
raise UnsupportedBranch(node.name)
elif not node.variable in terms:
raise UnsupportedBranch(node.name)
self.mayneedsel.add(node.name)
# set scope so we can insert types restriction properly
newvar = newroot.get_variable(node.name)
newvar.stinfo['scope'] = self.scopes.get(node.variable.scope, newroot)
vref = VariableRef(newvar)
self._pending_vrefs.append(vref)
return vref, node
def visit_constant(self, node, newroot, terms):
return copy_node(newroot, node), node
def visit_default(self, node, newroot, terms):
subparts, node = self._visit_children(node, newroot, terms)
return copy_node(newroot, node, subparts), node
visit_comparison = visit_mathexpression = visit_constant = visit_function = visit_default
visit_sort = visit_sortterm = visit_default
def _visit_children(self, node, newroot, terms):
subparts = []
for i in xrange(len(node.children)):
child = node.children[i]
newchild, child_ = child.accept(self, newroot, terms)
if not child is child_:
node = child_.parent
if newchild is not None:
subparts.append(newchild)
return subparts, node
def process_selection(self, newroot, terms, rqlst):
if self.final:
for term in rqlst.selection:
newroot.append_selected(term.copy(newroot))
for vref in term.get_nodes(VariableRef):
self.needsel.add(vref.name)
return
for term in rqlst.selection:
vrefs = term.get_nodes(VariableRef)
if vrefs:
supportedvars = []
for vref in vrefs:
var = vref.variable
if var in terms:
supportedvars.append(vref)
continue
else:
self.needsel.add(vref.name)
break
else:
for vref in vrefs:
newroot.append_selected(vref.copy(newroot))
supportedvars = []
for vref in supportedvars:
if not vref in newroot.get_selected_variables():
newroot.append_selected(VariableRef(newroot.get_variable(vref.name)))
def add_necessary_selection(self, newroot, terms):
selected = tuple(newroot.get_selected_variables())
for varname in terms:
var = newroot.defined_vars[varname]
for vref in var.references():
rel = vref.relation()
if rel is None and vref in selected:
# already selected
break
else:
selvref = VariableRef(var)
newroot.append_selected(selvref)
if newroot.groupby:
newroot.add_group_var(VariableRef(selvref.variable, noautoref=1))