xfunc.c

关系型数据库 Postgresql 6.5.2

	tupl = SearchSysCacheTuple(PROOID,
							   ObjectIdGetDatum(funcid),
							   0, 0, 0);
	if (!HeapTupleIsValid(tupl))
		elog(ERROR, "Cache lookup failed for procedure %u", funcid);
	proc = (Form_pg_proc) GETSTRUCT(tupl);

	/*
	 * * if it's a Postquel function, its cost is stored in the *
	 * associated plan.
	 */
	if (proc->prolang == SQLlanguageId)
	{
		LispValue	tmpplan;
		List		planlist;

		if (IsA(node, Oper) ||get_func_planlist((Func) node) == LispNil)
		{
			Oid		   *argOidVect;		/* vector of argtypes */
			char	   *pq_src; /* text of PQ function */
			int			nargs;	/* num args to PQ function */
			QueryTreeList *queryTree_list;		/* dummy variable */

			/*
			 * * plan the function, storing it in the Func node for later *
			 * use by the executor.
			 */
			pq_src = (char *) textout(&(proc->prosrc));
			nargs = proc->pronargs;
			if (nargs > 0)
				argOidVect = proc->proargtypes;
			planlist = (List) pg_parse_and_plan(pq_src, argOidVect, nargs,
										   &parseTree_list, None, FALSE);
			if (IsA(node, Func))
				set_func_planlist((Func) node, planlist);

		}
		else
		{						/* plan has been cached inside the Func
								 * node already */
			planlist = get_func_planlist((Func) node);
		}

		/*
		 * * Return the sum of the costs of the plans (the PQ function *
		 * may have many queries in its body).
		 */
		foreach(tmpplan, planlist)
			cost += get_cost((Plan) lfirst(tmpplan));
		return cost;
	}
	else
	{							/* it's a C function */

		/*
		 * *  find the cost of evaluating the function's arguments *  and
		 * the width of the operands
		 */
		for (tmpclause = args; tmpclause != LispNil;
			 tmpclause = lnext(tmpclause))
		{

			if ((operand = lfirst(tmpclause)) != LispNil)
			{
				cost += xfunc_local_expense(operand);
				width += xfunc_width(operand);
			}
		}

		/*
		 * * when stats become available, add in cost of accessing
		 * secondary * and tertiary storage here.
		 */
		return (cost +
				(Cost) proc->propercall_cpu +
		(Cost) proc->properbyte_cpu * (Cost) proc->probyte_pct / 100.00 *
				(Cost) width

		/*
		 * Pct_of_obj_in_mem DISK_COST * proc->probyte_pct/100.00 * width
		 * Pct_of_obj_on_disk + ARCH_COST * proc->probyte_pct/100.00 *
		 * width Pct_of_obj_on_arch
		 */
			);
	}
}

/*
 ** xfunc_width
 **    recursively find the width of a expression
 */

int
xfunc_width(LispValue clause)
{
	Relation	rd;				/* Relation Descriptor */
	HeapTuple	tupl;			/* structure to hold a cached tuple */
	Form_pg_type type;			/* structure to hold a type tuple */
	int			retval = 0;

	if (IsA(clause, Const))
	{
		/* base case: width is the width of this constant */
		retval = get_constlen((Const) clause);
		goto exit;
	}
	else if (IsA(clause, ArrayRef))
	{
		/* base case: width is width of the refelem within the array */
		retval = get_refelemlength((ArrayRef) clause);
		goto exit;
	}
	else if (IsA(clause, Var))
	{
		/* base case: width is width of this attribute */
		tupl = SearchSysCacheTuple(TYPOID,
							 ObjectIdGetDatum(get_vartype((Var) clause)),
								   0, 0, 0);
		if (!HeapTupleIsValid(tupl))
			elog(ERROR, "Cache lookup failed for type %u",
				 get_vartype((Var) clause));
		type = (Form_pg_type) GETSTRUCT(tupl);
		if (get_varattno((Var) clause) == 0)
		{
			/* clause is a tuple.  Get its width */
			rd = heap_open(type->typrelid);
			retval = xfunc_tuple_width(rd);
			heap_close(rd);
		}
		else
		{
			/* attribute is a base type */
			retval = type->typlen;
		}
		goto exit;
	}
	else if (IsA(clause, Param))
	{
		if (typeidTypeRelids(get_paramtype((Param) clause)))
		{
			/* Param node returns a tuple.	Find its width */
			rd = heap_open(typeidTypeRelids(get_paramtype((Param) clause)));
			retval = xfunc_tuple_width(rd);
			heap_close(rd);
		}
		else if (get_param_tlist((Param) clause) != LispNil)
		{
			/* Param node projects a complex type */
			Assert(length(get_param_tlist((Param) clause)) == 1);		/* sanity */
			retval = xfunc_width((LispValue)
					  get_expr(lfirst(get_param_tlist((Param) clause))));
		}
		else
		{
			/* Param node returns a base type */
			retval = typeLen(typeidType(get_paramtype((Param) clause)));
		}
		goto exit;
	}
	else if (IsA(clause, Iter))
	{

		/*
		 * * An Iter returns a setof things, so return the width of a
		 * single * thing. * Note:	THIS MAY NOT WORK RIGHT WHEN AGGS GET
		 * FIXED, * SINCE AGG FUNCTIONS CHEW ON THE WHOLE SETOF THINGS!!!! *
		 * This whole Iter business is bogus, anyway.
		 */
		retval = xfunc_width(get_iterexpr((Iter) clause));
		goto exit;
	}
	else if (fast_is_clause(clause))
	{

		/*
		 * * get function associated with this Oper, and treat this as * a
		 * Func
		 */
		tupl = SearchSysCacheTuple(OPROID,
					   ObjectIdGetDatum(get_opno((Oper) get_op(clause))),
								   0, 0, 0);
		if (!HeapTupleIsValid(tupl))
			elog(ERROR, "Cache lookup failed for procedure %u",
				 get_opno((Oper) get_op(clause)));
		return (xfunc_func_width
		((RegProcedure) (((Form_pg_operator) (GETSTRUCT(tupl)))->oprcode),
		 (LispValue) get_opargs(clause)));
	}
	else if (fast_is_funcclause(clause))
	{
		Func		func = (Func) get_function(clause);

		if (get_func_tlist(func) != LispNil)
		{

			/*
			 * this function has a projection on it.  Get the length of
			 * the projected attribute
			 */
			Assert(length(get_func_tlist(func)) == 1);	/* sanity */
			retval = xfunc_width((LispValue)
								 get_expr(lfirst(get_func_tlist(func))));
			goto exit;
		}
		else
		{
			return (xfunc_func_width((RegProcedure) get_funcid(func),
									 (LispValue) get_funcargs(clause)));
		}
	}
	else
	{
		elog(ERROR, "Clause node of undetermined type");
		return -1;
	}

exit:
	if (retval == -1)
		retval = VARLEN_DEFAULT;
	return retval;
}

/*
 ** xfunc_card_unreferenced:
 **   find all relations not referenced in clause, and multiply their
 ** cardinalities.	Ignore relation of cardinality 0.
 ** User may pass in referenced list, if they know it (useful
 ** for joins).
 */
static Count
xfunc_card_unreferenced(Query *queryInfo,
						LispValue clause, Relids referenced)
{
	Relids		unreferenced,
				allrelids = LispNil;
	LispValue	temp;

	/* find all relids of base relations referenced in query */
	foreach(temp, queryInfo->base_rel_list)
	{
		Assert(lnext(get_relids((RelOptInfo) lfirst(temp))) == LispNil);
		allrelids = lappend(allrelids,
						  lfirst(get_relids((RelOptInfo) lfirst(temp))));
	}

	/* find all relids referenced in query but not in clause */
	if (!referenced)
		referenced = xfunc_find_references(clause);
	unreferenced = set_difference(allrelids, referenced);

	return xfunc_card_product(unreferenced);
}

/*
 ** xfunc_card_product
 **   multiple together cardinalities of a list relations.
 */
Count
xfunc_card_product(Query *queryInfo, Relids relids)
{
	LispValue	cinfonode;
	LispValue	temp;
	RelOptInfo	currel;
	Cost		tuples;
	Count		retval = 0;

	foreach(temp, relids)
	{
		currel = get_rel(lfirst(temp));
		tuples = get_tuples(currel);

		if (tuples)
		{						/* not of cardinality 0 */
			/* factor in the selectivity of all zero-cost clauses */
			foreach(cinfonode, get_restrictinfo(currel))
			{
				if (!xfunc_expense(queryInfo, get_clause((RestrictInfo) lfirst(cinfonode))))
					tuples *= compute_clause_selec(queryInfo,
							get_clause((RestrictInfo) lfirst(cinfonode)),
												   LispNil);
			}

			if (retval == 0)
				retval = tuples;
			else
				retval *= tuples;
		}
	}
	if (retval == 0)
		retval = 1;				/* saves caller from dividing by zero */
	return retval;
}


/*
 ** xfunc_find_references:
 **   Traverse a clause and find all relids referenced in the clause.
 */
List
xfunc_find_references(LispValue clause)
{
	List		retval = (List) LispNil;
	LispValue	tmpclause;

	/* Base cases */
	if (IsA(clause, Var))
		return lispCons(lfirst(get_varid((Var) clause)), LispNil);
	else if (IsA(clause, Const) ||IsA(clause, Param))
		return (List) LispNil;

	/* recursion */
	else if (IsA(clause, Iter))

		/*
		 * Too low. Should multiply by the expected number of iterations.
		 * maybe
		 */
		return xfunc_find_references(get_iterexpr((Iter) clause));
	else if (IsA(clause, ArrayRef))
		return xfunc_find_references(get_refexpr((ArrayRef) clause));
	else if (fast_is_clause(clause))
	{
		/* string together result of all operands of Oper */
		for (tmpclause = (LispValue) get_opargs(clause); tmpclause != LispNil;
			 tmpclause = lnext(tmpclause))
			retval = nconc(retval, xfunc_find_references(lfirst(tmpclause)));
		return retval;
	}
	else if (fast_is_funcclause(clause))
	{
		/* string together result of all args of Func */
		for (tmpclause = (LispValue) get_funcargs(clause);
			 tmpclause != LispNil;
			 tmpclause = lnext(tmpclause))
			retval = nconc(retval, xfunc_find_references(lfirst(tmpclause)));
		return retval;
	}
	else if (fast_not_clause(clause))
		return xfunc_find_references(lsecond(clause));
	else if (fast_or_clause(clause) || fast_and_clause(clause))
	{
		/* string together result of all operands of OR */
		for (tmpclause = lnext(clause); tmpclause != LispNil;
			 tmpclause = lnext(tmpclause))
			retval = nconc(retval, xfunc_find_references(lfirst(tmpclause)));
		return retval;
	}
	else
	{
		elog(ERROR, "Clause node of undetermined type");
		return (List) LispNil;
	}
}

/*
 ** xfunc_primary_join:
 **   Find the primary join clause: for Hash and Merge Joins, this is the
 ** min rank Hash or Merge clause, while for Nested Loop it's the
 ** min rank pathclause
 */
LispValue
xfunc_primary_join(JoinPath pathnode)
{
	LispValue	joinclauselist = get_pathrestrictinfo(pathnode);
	RestrictInfo mincinfo;
	LispValue	tmplist;
	LispValue	minclause = LispNil;
	Cost		minrank,
				tmprank;

	if (IsA(pathnode, MergePath))
	{
		for (tmplist = get_path_mergeclauses((MergePath) pathnode),
			 minclause = lfirst(tmplist),
			 minrank = xfunc_rank(minclause);
			 tmplist != LispNil;
			 tmplist = lnext(tmplist))
			if ((tmprank = xfunc_rank(lfirst(tmplist)))
				< minrank)
			{
				minrank = tmprank;
				minclause = lfirst(tmplist);
			}
		return minclause;
	}
	else if (IsA(pathnode, HashPath))
	{
		for (tmplist = get_path_hashclauses((HashPath) pathnode),
			 minclause = lfirst(tmplist),
			 minrank = xfunc_rank(minclause);
			 tmplist != LispNil;
			 tmplist = lnext(tmplist))
			if ((tmprank = xfunc_rank(lfirst(tmplist)))
				< minrank)
			{
				minrank = tmprank;
				minclause = lfirst(tmplist);
			}
		return minclause;
	}

	/* if we drop through, it's nested loop join */
	if (joinclauselist == LispNil)
		return LispNil;

	for (tmplist = joinclauselist, mincinfo = (RestrictInfo) lfirst(joinclauselist),
		 minrank = xfunc_rank(get_clause((RestrictInfo) lfirst(tmplist)));
		 tmplist != LispNil;
		 tmplist = lnext(tmplist))
		if ((tmprank = xfunc_rank(get_clause((RestrictInfo) lfirst(tmplist))))
			< minrank)
		{
			minrank = tmprank;
			mincinfo = (RestrictInfo) lfirst(tmplist);
		}
	return (LispValue) get_clause(mincinfo);
}

/*
 ** xfunc_get_path_cost
 **   get the expensive function costs of the path
 */
Cost
xfunc_get_path_cost(Query *queryInfo, Path pathnode)
{
	Cost		cost = 0;
	LispValue	tmplist;
	Cost		selec = 1.0;

	/*
	 * * first add in the expensive local function costs. * We ensure that
	 * the clauses are sorted by rank, so that we * know (via
	 * selectivities) the number of tuples that will be checked * by each
	 * function.  If we're not doing any optimization of expensive *
	 * functions, we don't sort.
	 */
	if (XfuncMode != XFUNC_OFF)
		set_locrestrictinfo(pathnode, lisp_qsort(get_loc_restrictinfo(pathnode),
												 xfunc_cinfo_compare));
	for (tmplist = get_loc_restrictinfo(pathnode), selec = 1.0;
		 tmplist != LispNil;
		 tmplist = lnext(tmplist))
	{
		cost += (Cost) (xfunc_local_expense(get_clause((RestrictInfo) lfirst(tmplist)))
					  * (Cost) get_tuples(get_parent(pathnode)) * selec);
		selec *= compute_clause_selec(queryInfo,
							  get_clause((RestrictInfo) lfirst(tmplist)),
									  LispNil);
	}

	/*
	 * * Now add in any node-specific expensive function costs. * Again,
	 * we must ensure that the clauses are sorted by rank.
	 */
	if (IsA(pathnode, JoinPath))
	{
		if (XfuncMode != XFUNC_OFF)
			set_pathrestrictinfo((JoinPath) pathnode, lisp_qsort
							  (get_pathrestrictinfo((JoinPath) pathnode),
							   xfunc_cinfo_compare));
		for (tmplist = get_pathrestrictinfo((JoinPath) pathnode), selec = 1.0;
			 tmplist != LispNil;
			 tmplist = lnext(tmplist))
		{
			cost += (Cost) (xfunc_local_expense(get_clause((RestrictInfo) lfirst(tmplist)))
					  * (Cost) get_tuples(get_parent(pathnode)) * selec);
			selec *= compute_clause_selec(queryInfo,
							  get_clause((RestrictInfo) lfirst(tmplist)),
										  LispNil);
		}
	}
	if (IsA(pathnode, HashPath))
	{
		if (XfuncMode != XFUNC_OFF)
			set_path_hashclauses
				((HashPath) pathnode,
				 lisp_qsort(get_path_hashclauses((HashPath) pathnode),
							xfunc_clause_compare));
		for (tmplist = get_path_hashclauses((HashPath) pathnode), selec = 1.0;
			 tmplist != LispNil;
			 tmplist = lnext(tmplist))
		{
			cost += (Cost) (xfunc_local_expense(lfirst(tmplist))
					  * (Cost) get_tuples(get_parent(pathnode)) * selec);
			selec *= compute_clause_selec(queryInfo,
										  lfirst(tmplist), LispNil);
		}
	}
	if (IsA(pathnode, MergePath))
	{
		if (XfuncMode != XFUNC_OFF)
			set_path_mergeclauses
				((MergePath) pathnode,
				 lisp_qsort(get_path_mergeclauses((MergePath) pathnode),
							xfunc_clause_compare));
		for (tmplist = get_path_mergeclauses((MergePath) pathnode), selec = 1.0;