Class: Locomotive::RelationalAlgebra::SurrogateList

Inherits:
Object
  • Object
show all
Defined in:
lib/locomotive/relational_algebra/query_information.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(hash) ⇒ SurrogateList

Returns a new instance of SurrogateList.



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 22

def initialize(hash)
  self.surrogates = hash   
end

Instance Attribute Details

#surrogates ⇒ Object

Returns the value of attribute surrogates.



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 19

def surrogates
  @surrogates
end

Instance Method Details

#+(sur) ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 31

def +(sur)
  SurrogateList.new(surrogates.merge(sur.surrogates))
end

#clone ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 156

def clone
  # only clone the attributes since we don't modify
  # the plan
  SurrogateList.new( surrogates.map { |k,v| [k.clone,v] }.to_hash )
end

#delete_if(&lambda) ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 35

def delete_if(&lambda)
  SurrogateList.new(self.clone.surrogates.delete_if(&lambda))
end

#filter_and_adapt(items) ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 162

def filter_and_adapt(items)
   item_min = items.min
   # we are modifying the structure itself
   # so we have to clone it (sideeffect)
   surr_new = self.delete_if do |it, itbl|
     !items.member?(it)
   end
  # adapt the keys
  surr_new.map { |k,p| [Item.new(k.id - (item_min.id - 1)), p] }
end

#itapp(q_0, *itbls) ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 39

def itapp(q_0, *itbls)
  if itbls.any? { |i| self.keys != i.keys }
    raise ITblsNotEqual,
          "some itbls keys are not equal"
  end
    
  if self.empty? and 
     itbls.all? { |i| i.empty? }
    return SurrogateList.new( {} )
  end
    
  c = self.first.first
    
  q1_in = self[c]
  qs_in = itbls.map { |itbl| itbl[c] }

  q1 = q1_in.plan
  qs = qs_in.map { |q| q.plan }
  cols_q1, itbls_q1 = q1_in.column_structure, q1_in.surrogates
  ord, ord_, item_, item__ = Iter.new(2), Iter.new(4),
                                 Iter.new(3), Item.new(3)

  # (1)
  q1_ = q1.attach(AttachItem.new(ord, RAtomic.new(1, RNat.type)))
  q = qs.zip(2..qs.size+1).reduce(q1_) do |p1,p2|
        p1.union(
           p2.first.attach(AttachItem.new(ord, RAtomic.new(p2.last, RNat.type))))
      end.row_num(item_, [], [Iter.new(1), ord, Pos.new(1)])
  
  #(2)
  c_new = Iter.new(5)
  q_ = q_0.project( ord => [ord_],
                    item_ => [item__],
                    c     => [c_new] ).
           theta_join(q, [Equivalence.new(ord_, ord),
                          Equivalence.new(c_new, Iter.new(1))] ).
           project( { item__ => [Iter.new(1)],
                      Pos.new(1) => [Pos.new(1)],
                      item_ => itbls_q1.keys  }.
                      merge(
                        (cols_q1 - itbls_q1.keys).items.collect do |col|
                          [col, [col]]
                        end.to_hash) )

   # (3)          
   itbl_ = q1_in.surrogates.itapp(q, *qs_in.map { |q| q.surrogates })
   # (4)
   itbl__ = self.delete_if { |k,v| k == c}.
              itapp(q_0, *itbls.map { |i| i.delete_if { |k,v| k == c} })
   # (5)
   SurrogateList.new( { c => QueryInformationNode.new(
                               q_, cols_q1, itbl_) } ) + itbl__
end

#itsel(q_0) ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 93

def itsel(q_0)
  return SurrogateList.new({}) if self.empty? 

  c = self.first.first
  cols, itbls, q = self[c].column_structure, self[c].surrogates, self[c].plan
  c_ = (self.keys + cols.items).max.inc

  # (1)
  q_ = q.equi_join(q_0.project( c => [c_]), Iter.new(1), c_).
         project( [Iter.new(1), Pos.new(1)] + cols.items )

  itbls_ = itbls.itsel(q_)
  itbls__ = self.delete_if { |k,v| k == c }.itsel(q_0)

  SurrogateList.new(
    { c => QueryInformationNode.new(q_, cols, itbls_) }.
    merge( itbls__.to_a.to_hash ) )
end

#join ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 112

def join
  itbls = surrogates.to_a

  itbls.rest.reduce(itbls.first.last) do |qi,surr|
    # the query_information node
    qin_j = surr.last
     
    cols_j  = surr.last.column_structure
    itbls_j = surr.last.surrogates
    cols_c  = qi.column_structure
    itbls_c = qi.surrogates

    # adapt cols
    cols_j_ = cols_j.clone
    cols_j_.items.each { |i| i.inc!(qi.column_structure.count) }
    # adapt itbls
    itbls_j_ = itbls_j.map { |k,q| [k.inc(qi.column_structure.count), q] }

    # calculate new plan
    q_j = qin_j.plan.project({ Iter.new(1) => [Iter.new(2)],
                               Pos.new(1)  => [Pos.new(2)] }.
                              merge(
                                cols_j.items.zip(cols_j_.items).
                                  map do |old,new|
                                    [old,[new]]
                                  end.to_hash))

    q_ = q_j.theta_join(qi.plan, [Equivalence.new(Iter.new(2), Iter.new(1)),
                                          Equivalence.new(Pos.new(2), Pos.new(1))]).
                     project([Iter.new(1), Pos.new(1)] + cols_c.items + cols_j_.items)


    QueryInformationNode.new(q_, cols_c + cols_j_, itbls_c + itbls_j_)
  end
end

#map(&block) ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 26

def map(&block)
  SurrogateList.new(
    surrogates.map(&block).to_hash)
end

#set(var, plan) ⇒ Object 



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# File 'lib/locomotive/relational_algebra/query_information.rb', line 148

def set(var, plan)
  self.map do |item, itbl|
    [item,QueryInformationNode.new(itbl.plan.set(var, plan), 
                                   itbl.column_structure,
                                   itbl.surrogates.set(var,plan))]
  end
end