diff --git a/app/controllers/concerns/data_table.rb b/app/controllers/concerns/data_table.rb
index d8bac14..abdfb4d 100644
--- a/app/controllers/concerns/data_table.rb
+++ b/app/controllers/concerns/data_table.rb
@@ -1,52 +1,52 @@
+class DataTable
 
-module DataTable
-  extend ActiveSupport::Concern
+  def initialize user, params
+    @user = user
+    @params = sanitize_params(params)
+    @transactions = TransactionsQuery.new(@user)
+    @table = @transactions.arel_table
+  end
 
-  def apply_filter(user, params)
-    params = sanitize_params(params)
-    selection = user.transactions
+  def json
+    response_json(@params[:draw], data)
+  end
 
-    # filter time
-    lower = params[:columns][:time][:lower]
-    upper = params[:columns][:time][:upper]
-    if lower and upper
-      selection = selection.where(created_at: lower..upper)
-    elsif lower
-      selection = selection.where('created_at > :lower', lower: lower)
-    elsif upper
-      selection = selection.where('created_at < :upper', upper: upper)
-    end
+  def data
+    ActiveRecord::Base.connection.execute(self.query.to_sql)
+  end
 
-    # filter amount TODO this filters on absolute value
-    lower = params[:columns][:amount][:lower]
-    upper = params[:columns][:amount][:upper]
-    if lower and upper
-      selection = selection.where(amount: lower..upper)
-    elsif lower
-      selection = selection.where('amount > :lower', lower: lower)
-    elsif upper
-      selection = selection.where('amount < :upper', upper: upper)
-    end
+  def query
+    pred = predicates
+    q = @transactions.query
+    q = q.where(pred) if pred
+    q
+  end
 
-    # filter peer # TODO peer.name
-    peer = params[:columns][:peer][:value]
-    if peer
-      selection = selection.where("(debtor_id = :id AND creditor_id LIKE :peer) OR (creditor_id = :id AND debtor_id LIKE :peer)", id: user.id, peer: "%#{peer}%")
-    end
+  def predicates
+    [ *range_predicates(:amount),
+      *range_predicates(:time),
+      eq_predicate(:peer),
+      eq_predicate(:issuer),
+      like_predicate(:message)
+    ].compact.inject { |l, r| l.and(r) }
+  end
 
-    # filter issuer # TODO issuer.name
-    issuer = params[:columns][:issuer][:value]
-    if issuer
-      selection = selection.where("issuer_id LIKE :re", re: "%#{issuer}%")
-    end
+  def range_predicates name
+    col = @params[:columns][name]
+    [
+      (@table[:name].gteq(col[:lower]) if col[:lower]),
+      (@table[:name].lteq(col[:upper]) if col[:upper])
+    ]
+  end
 
-    # filter message
-    message = params[:columns][:message][:value]
-    if message
-      selection = selection.where("message LIKE :re", re: "%#{message}%")
-    end
+  def eq_predicate name
+    value = @params[:columns][:name][:value]
+    @table[:name].eq(value) if value
+  end
 
-    selection_to_json(user, params[:draw], selection)
+  def like_predicate name
+    value = @params[:columns][:name][:value]
+    @table[:name].matches("%#{value}%") if value
   end
 
   private
@@ -78,18 +78,19 @@ module DataTable
     return clean
   end
 
-  def selection_to_json(user, draw, selection)
+  def response_json(draw, selection)
     {
       draw: draw,
-      recordsTotal: user.transactions.count,
+      recordsTotal: @user.transactions.count,
       recordsFiltered: selection.count,
-      data: selection.offset(params[:start]).take(params[:length]).map { |transaction| {
-        time: transaction.created_at,
-        amount: transaction.signed_amount_for(user),
-        peer: transaction.peer_of(user).try(:name),
-        issuer: transaction.issuer.name,
-        message: transaction.message,
-      }}
+      #data: selection.offset(params[:start]).take(params[:length]).map { |transaction| {
+        #time: transaction.created_at,
+        #amount: transaction.signed_amount_for(user),
+        #peer: transaction.peer_of(user).try(:name),
+        #issuer: transaction.issuer.name,
+        #message: transaction.message,
+      #}}
+      data: selection
     }
   end
 end
diff --git a/app/controllers/concerns/transactions_query.rb b/app/controllers/concerns/transactions_query.rb
new file mode 100644
index 0000000..8bfd543
--- /dev/null
+++ b/app/controllers/concerns/transactions_query.rb
@@ -0,0 +1,74 @@
+class TransactionsQuery
+  attr_reader :arel_table
+
+  def initialize user
+    @user = user
+    @transactions = Arel::Table.new(:transactions)
+    @perspectived = Arel::Table.new(:perspectived_transactions)
+    @peers = Arel::Table.new(:users).alias('peers')
+    @arel_table = Arel::Table.new(@user.name.concat('_transactions'))
+  end
+
+  def query
+    Arel::SelectManager.new(ActiveRecord::Base)
+      .from(arel)
+      .project(Arel.star)
+  end
+
+  def arel
+    Arel::Nodes::TableAlias.new(
+      issued_by(User).union(:all, issued_by(Client)),
+      arel_table.name
+    )
+  end
+
+  def issued_by klass
+    issuers = klass.arel_table.alias('issuer')
+    Arel::SelectManager.new(ActiveRecord::Base)
+      .from(transactions)
+      .join(@peers).on(@peers[:id].eq(@perspectived[:peer_id]))
+      .join(issuers).on(issuers[:id].eq(@perspectived[:issuer_id]))
+      .where(@perspectived[:issuer_type].eq(klass.name))
+      .project(
+        @perspectived[:amount],
+        @perspectived[:time],
+        @perspectived[:message],
+        @peers[:name].as('peer'),
+        issuers[:name].as('issuer')
+      )
+  end
+
+  def transactions
+    Arel::Nodes::TableAlias.new(
+      incoming.union(:all, outgoing),
+      @perspectived.name
+    )
+  end
+
+  def outgoing
+    @transactions
+      .where(@transactions[:debtor_id].eq(@user.id))
+      .project(
+        (@transactions[:amount]*Arel::Nodes::SqlLiteral.new("-1")).as('amount'),
+        @transactions[:creditor_id].as('peer_id'),
+        @transactions[:created_at].as('time'),
+        @transactions[:issuer_id],
+        @transactions[:issuer_type],
+        @transactions[:message]
+      )
+  end
+
+  def incoming
+    @user.incoming_transactions.arel
+    @transactions
+      .where(@transactions[:debtor_id].eq(@user.id))
+      .project(
+        @transactions[:amount],
+        @transactions[:debtor_id].as('peer_id'),
+        @transactions[:created_at].as('time'),
+        @transactions[:issuer_id],
+        @transactions[:issuer_type],
+        @transactions[:message]
+      )
+  end
+end
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 6dcaeb3..d1e5a0a 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -1,13 +1,14 @@
 class UsersController < ApplicationController
   load_and_authorize_resource
 
-  include DataTable
-
   def show
     @user = User.find(params[:id])
     respond_to do |format|
       format.html
-      format.json { render json: apply_filter(@user, params) }
+      format.json do
+        datatable = DataTable.new(@user, params)
+        render json: datatable.json
+      end
     end
   end