/*     
 *      FILE
 *     	relnode
 *     
 *      DESCRIPTION
 *     	Relation manipulation routines
 *     
 *      EXPORTS
 *     		get_rel
 *     		rel-member
 *
 *	$Header: /private/postgres/src/planner/util/RCS/relnode.c,v 1.14 1992/03/31 23:15:08 mer Exp $
 */

#include "planner/internal.h"
#include "planner/relnode.h"
#include "nodes/relation.h"
#include "planner/plancat.h"

/* ----------------
 *	Rel creator declaration
 * ----------------
 */
extern Rel RMakeRel();

/*    
 *    	get_rel
 *    
 *    	Returns relation entry corresponding to 'relid', creating a new one if
 *    	necessary.  
 *    
 */

/*  .. add-clause-to-rels, add-join-clause-info-to-rels, add-vars-to-rels
 *  .. find-all-join-paths, find-clause-joins, find-clauseless-joins
 *  .. initialize-targetlist
 */

Rel
get_rel(relid)
     LispValue relid ;
{
    Rel rel;

    if (listp(relid)) {
	rel = rel_member(relid, _join_relation_list_);
      }
    else {
	List relids = lispCons(relid, LispNil);
	rel = rel_member(relids, _base_relation_list_);
	if (null(rel)) {
	    rel = RMakeRel();
	    set_relids(rel,relids);
	    set_indexed(rel,false);
	    set_pages(rel, 0);
	    set_tuples(rel,0);
	    set_width(rel,0);
	    set_targetlist(rel,LispNil);
	    set_pathlist(rel,LispNil);
	    set_unorderedpath(rel,(PathPtr)NULL);
	    set_cheapestpath(rel,(PathPtr)NULL);
	    set_classlist(rel,(List)NULL);
	    set_ordering(rel,LispNil);
	    set_clauseinfo(rel,LispNil);
	    set_joininfo(rel,LispNil);
	    set_innerjoin(rel,LispNil);
	    set_superrels(rel,LispNil);

	    _base_relation_list_ = lispCons((LispValue)rel,
					    _base_relation_list_);

	    if(listp(relid)) {
		/*    If the relation is a materialized relation, assume 
		      constants for sizes. */
		set_pages(rel,_TEMP_RELATION_PAGES_);
		set_tuples(rel,_TEMP_RELATION_TUPLES_);

	    } else {
		/*    Otherwise, retrieve relation characteristics from the */
		/*    system catalogs. */

	      int reltuples = 0;
	      LispValue relinfo = relation_info((ObjectId)CInteger(relid));

	      reltuples = CInteger(CADDR(relinfo));
	      set_indexed(rel, !zerop(nth(0,relinfo)));
	      set_pages(rel,(Count)CInteger(CADR(relinfo)));
	      set_tuples(rel,(Count)reltuples);
	    } 
	}
      }
    return(rel);
}

/*    
 *    	rel-member
 *    
 *    	Determines whether a relation of id 'relid' is contained within a list
 *    	'rels'.  
 *    
 *    	Returns the corresponding entry in 'rels' if it is there.
 *    
 */

/*  .. find-all-join-paths, get_rel
 */

Rel
rel_member(relid, rels)
     List relid;
     List rels;
{
    LispValue temp = LispNil;
    LispValue temprelid = LispNil;
    
    if(consp(relid) && consp(rels)) {
	foreach(temp,rels) {
	    temprelid = (LispValue)get_relids((Rel)CAR(temp));
	    if(same(temprelid, relid))   
	      return((Rel)(CAR(temp)));
	  }
      } 
    return(NULL);
}