.. -*- coding: utf-8 -*-

Déroulement de l'éxecution d'une requête en multi-source avec insertion de sécurité
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* 3 sources (system, ldap (Euser) et rql (Card)
* permission en lecture Card is elle appartient à l'utilisateur

Soit la requête de départ: ::

  Any X,T WHERE X owned_by U, U login "syt", X title T

1. récupération arbre de syntaxe et solution (+cache) ::

     -> {X: Card, U: Euser}, {X: Blog, U: Euser}, {X: Bookmark, U: Euser}

2. insertion sécurité ::

     -> Any X,T WHERE X owned_by U, U login "syt", X title T, EXISTS(X owned_by UEID) / {X: Card, U: Euser}
        Any X,T WHERE X owned_by U, U login "syt", X title T / {X: Blog, U: Euser}, {X: Bookmark, U: Euser}
   
3. construction plan
   0. preprocessing (annotation des arbres de syntaxe)
   
   1. Any U WHERE U login "syt" / {U: Euser}
      [system+ldap] => table1/varmap1{U:U2}
      
   2. Any X,T WHERE X owned_by U2, X title T / {X: Blog, U: Euser}, {X: Bookmark, U: Euser}
      [varmap1|system] => TABLE2
      
   3 Deux alernatives:
   
     1. Any X,T WHERE X is Card, X title T {X: Card} ::

          [system+rql] => table3/varmap3{X:X3, T:T3}
	   
        Any X3,T3 WHERE X3 owned_by U2, X3 title T3, EXISTS(X owned_by UEID) / {X3: Card, U2: Euser} ::

          [(varmap1, varmap3)|system] => TABLE2
       
     2 Any X WHERE X is Card X owned_by U2, EXISTS(X owned_by UEID) / {X: Card, U2: Euser} ::

          [varmap1|system] => EIDS
	   
       Any X,T WHERE X title T, X eid IN(EIDS) {X: Card} ::
	 
          [system+rql] => TABLE2
   
   4. renvoie contenu TABLE2.
      Note : si aggrégat / tri / distinct TABLE2 est nécessairement une table temporaire et besoin d'une
      étape AggrStep supplémentaire
      
4. éxécution du plan

5. [construction description]

6. renvoie ResultSet

Notes sur UNION
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* en multi-sources, les résultats des unions peuvent être mélangés