pathnode.c

关系型数据库 Postgresql 6.5.2

				  RelOptInfo *rel,
				  RelOptInfo *index,
				  List *restriction_clauses,
				  bool is_join_scan)
{
	IndexPath  *pathnode = makeNode(IndexPath);

	pathnode->path.pathtype = T_IndexScan;
	pathnode->path.parent = rel;
	pathnode->path.pathorder = makeNode(PathOrder);
	pathnode->path.pathorder->ordtype = SORTOP_ORDER;
	pathnode->path.pathorder->ord.sortop = index->ordering;

	pathnode->indexid = index->relids;
	pathnode->indexkeys = index->indexkeys;
	pathnode->indexqual = NIL;

	/*
	 * copy restrictinfo list into path for expensive function processing
	 * JMH, 7/7/92
	 */
	pathnode->path.loc_restrictinfo = set_difference((List *) copyObject((Node *) rel->restrictinfo),
										   (List *) restriction_clauses);

	/*
	 * The index must have an ordering for the path to have (ordering)
	 * keys, and vice versa.
	 */
	if (pathnode->path.pathorder->ord.sortop)
	{
		pathnode->path.pathkeys = collect_index_pathkeys(index->indexkeys,
														 rel->targetlist);

		/*
		 * Check that the keys haven't 'disappeared', since they may no
		 * longer be in the target list (i.e., index keys that are not
		 * relevant to the scan are not applied to the scan path node, so
		 * if no index keys were found, we can't order the path).
		 */
		if (pathnode->path.pathkeys == NULL)
			pathnode->path.pathorder->ord.sortop = NULL;
	}
	else
		pathnode->path.pathkeys = NULL;

	if (is_join_scan || restriction_clauses == NULL)
	{

		/*
		 * Indices used for joins or sorting result nodes don't restrict
		 * the result at all, they simply order it, so compute the scan
		 * cost accordingly -- use a selectivity of 1.0.
		 */
/* is the statement above really true?	what about IndexScan as the
   inner of a join? */
		pathnode->path.path_cost = cost_index(lfirsti(index->relids),
											  index->pages,
											  1.0,
											  rel->pages,
											  rel->tuples,
											  index->pages,
											  index->tuples,
											  false);
#ifdef NOT_USED
		/* add in expensive functions cost!  -- JMH, 7/7/92 */
		if (XfuncMode != XFUNC_OFF)
		{
			pathnode->path_cost = (pathnode->path_cost +
								 xfunc_get_path_cost((Path *) pathnode));
		}
#endif
	}
	else
	{

		/*
		 * Compute scan cost for the case when 'index' is used with a
		 * restriction clause.
		 */
		List	   *attnos;
		List	   *values;
		List	   *flags;
		float		npages;
		float		selec;
		Cost		clausesel;

		get_relattvals(restriction_clauses,
					   &attnos,
					   &values,
					   &flags);
		index_selectivity(lfirsti(index->relids),
						  index->classlist,
						  get_opnos(restriction_clauses),
						  getrelid(lfirsti(rel->relids),
								   root->rtable),
						  attnos,
						  values,
						  flags,
						  length(restriction_clauses),
						  &npages,
						  &selec);
		/* each clause gets an equal selectivity */
		clausesel = pow(selec, 1.0 / (double) length(restriction_clauses));

		pathnode->indexqual = restriction_clauses;
		pathnode->path.path_cost = cost_index(lfirsti(index->relids),
											  (int) npages,
											  selec,
											  rel->pages,
											  rel->tuples,
											  index->pages,
											  index->tuples,
											  false);

#ifdef NOT_USED
		/* add in expensive functions cost!  -- JMH, 7/7/92 */
		if (XfuncMode != XFUNC_OFF)
			pathnode->path_cost += xfunc_get_path_cost((Path *) pathnode);
#endif

		/*
		 * Set selectivities of clauses used with index to the selectivity
		 * of this index, subdividing the selectivity equally over each of
		 * the clauses.
		 */

		/* XXX Can this divide the selectivities in a better way? */
		set_clause_selectivities(restriction_clauses, clausesel);
	}
	return pathnode;
}

/*
 * create_nestloop_path
 *	  Creates a pathnode corresponding to a nestloop join between two
 *	  relations.
 *
 * 'joinrel' is the join relation.
 * 'outer_rel' is the outer join relation
 * 'outer_path' is the outer join path.
 * 'inner_path' is the inner join path.
 * 'pathkeys' are the keys of the path
 *
 * Returns the resulting path node.
 *
 */
NestPath   *
create_nestloop_path(RelOptInfo *joinrel,
					 RelOptInfo *outer_rel,
					 Path *outer_path,
					 Path *inner_path,
					 List *pathkeys)
{
	NestPath   *pathnode = makeNode(NestPath);

	pathnode->path.pathtype = T_NestLoop;
	pathnode->path.parent = joinrel;
	pathnode->outerjoinpath = outer_path;
	pathnode->innerjoinpath = inner_path;
	pathnode->pathinfo = joinrel->restrictinfo;
	pathnode->path.pathkeys = pathkeys;
	pathnode->path.joinid = NIL;
	pathnode->path.outerjoincost = (Cost) 0.0;
	pathnode->path.loc_restrictinfo = NIL;
	pathnode->path.pathorder = makeNode(PathOrder);

	if (pathkeys)
	{
		pathnode->path.pathorder->ordtype = outer_path->pathorder->ordtype;
		if (outer_path->pathorder->ordtype == SORTOP_ORDER)
			pathnode->path.pathorder->ord.sortop = outer_path->pathorder->ord.sortop;
		else
			pathnode->path.pathorder->ord.merge = outer_path->pathorder->ord.merge;
	}
	else
	{
		pathnode->path.pathorder->ordtype = SORTOP_ORDER;
		pathnode->path.pathorder->ord.sortop = NULL;
	}

	pathnode->path.path_cost = cost_nestloop(outer_path->path_cost,
											 inner_path->path_cost,
											 outer_rel->size,
											 inner_path->parent->size,
											 page_size(outer_rel->size,
													   outer_rel->width),
											 IsA(inner_path, IndexPath));
	/* add in expensive function costs -- JMH 7/7/92 */
#ifdef NOT_USED
	if (XfuncMode != XFUNC_OFF)
		pathnode->path_cost += xfunc_get_path_cost((Path *) pathnode);
#endif
	return pathnode;
}

/*
 * create_mergejoin_path
 *	  Creates a pathnode corresponding to a mergejoin join between
 *	  two relations
 *
 * 'joinrel' is the join relation
 * 'outersize' is the number of tuples in the outer relation
 * 'innersize' is the number of tuples in the inner relation
 * 'outerwidth' is the number of bytes per tuple in the outer relation
 * 'innerwidth' is the number of bytes per tuple in the inner relation
 * 'outer_path' is the outer path
 * 'inner_path' is the inner path
 * 'pathkeys' are the new keys of the join relation
 * 'order' is the sort order required for the merge
 * 'mergeclauses' are the applicable join/restriction clauses
 * 'outersortkeys' are the sort varkeys for the outer relation
 * 'innersortkeys' are the sort varkeys for the inner relation
 *
 */
MergePath  *
create_mergejoin_path(RelOptInfo *joinrel,
					  int outersize,
					  int innersize,
					  int outerwidth,
					  int innerwidth,
					  Path *outer_path,
					  Path *inner_path,
					  List *pathkeys,
					  MergeOrder *order,
					  List *mergeclauses,
					  List *outersortkeys,
					  List *innersortkeys)
{
	MergePath  *pathnode = makeNode(MergePath);

	pathnode->jpath.path.pathtype = T_MergeJoin;
	pathnode->jpath.path.parent = joinrel;
	pathnode->jpath.outerjoinpath = outer_path;
	pathnode->jpath.innerjoinpath = inner_path;
	pathnode->jpath.pathinfo = joinrel->restrictinfo;
	pathnode->jpath.path.pathkeys = pathkeys;
	pathnode->jpath.path.pathorder = makeNode(PathOrder);
	pathnode->jpath.path.pathorder->ordtype = MERGE_ORDER;
	pathnode->jpath.path.pathorder->ord.merge = order;
	pathnode->path_mergeclauses = mergeclauses;
	pathnode->jpath.path.loc_restrictinfo = NIL;
	pathnode->outersortkeys = outersortkeys;
	pathnode->innersortkeys = innersortkeys;
	pathnode->jpath.path.path_cost = cost_mergejoin(outer_path->path_cost,
													inner_path->path_cost,
													outersortkeys,
													innersortkeys,
													outersize,
													innersize,
													outerwidth,
													innerwidth);
	/* add in expensive function costs -- JMH 7/7/92 */
#ifdef NOT_USED
	if (XfuncMode != XFUNC_OFF)
		pathnode->path_cost += xfunc_get_path_cost((Path *) pathnode);
#endif
	return pathnode;
}

/*
 * create_hashjoin_path--						XXX HASH
 *	  Creates a pathnode corresponding to a hash join between two relations.
 *
 * 'joinrel' is the join relation
 * 'outersize' is the number of tuples in the outer relation
 * 'innersize' is the number of tuples in the inner relation
 * 'outerwidth' is the number of bytes per tuple in the outer relation
 * 'innerwidth' is the number of bytes per tuple in the inner relation
 * 'outer_path' is the outer path
 * 'inner_path' is the inner path
 * 'pathkeys' are the new keys of the join relation
 * 'operator' is the hashjoin operator
 * 'hashclauses' are the applicable join/restriction clauses
 * 'outerkeys' are the sort varkeys for the outer relation
 * 'innerkeys' are the sort varkeys for the inner relation
 *
 */
HashPath   *
create_hashjoin_path(RelOptInfo *joinrel,
					 int outersize,
					 int innersize,
					 int outerwidth,
					 int innerwidth,
					 Path *outer_path,
					 Path *inner_path,
					 List *pathkeys,
					 Oid operator,
					 List *hashclauses,
					 List *outerkeys,
					 List *innerkeys)
{
	HashPath   *pathnode = makeNode(HashPath);

	pathnode->jpath.path.pathtype = T_HashJoin;
	pathnode->jpath.path.parent = joinrel;
	pathnode->jpath.outerjoinpath = outer_path;
	pathnode->jpath.innerjoinpath = inner_path;
	pathnode->jpath.pathinfo = joinrel->restrictinfo;
	pathnode->jpath.path.loc_restrictinfo = NIL;
	pathnode->jpath.path.pathkeys = pathkeys;
	pathnode->jpath.path.pathorder = makeNode(PathOrder);
	pathnode->jpath.path.pathorder->ordtype = SORTOP_ORDER;
	pathnode->jpath.path.pathorder->ord.sortop = NULL;
	pathnode->jpath.path.outerjoincost = (Cost) 0.0;
	pathnode->jpath.path.joinid = (Relids) NULL;
	/* pathnode->hashjoinoperator = operator;  */
	pathnode->path_hashclauses = hashclauses;
	pathnode->outerhashkeys = outerkeys;
	pathnode->innerhashkeys = innerkeys;
	pathnode->jpath.path.path_cost = cost_hashjoin(outer_path->path_cost,
												   inner_path->path_cost,
												   outerkeys,
												   innerkeys,
												   outersize, innersize,
												 outerwidth, innerwidth);
	/* add in expensive function costs -- JMH 7/7/92 */
#ifdef NOT_USED
	if (XfuncMode != XFUNC_OFF)
		pathnode->path_cost += xfunc_get_path_cost((Path *) pathnode);
#endif
	return pathnode;
}