ruleutils.c

关系型数据库 Postgresql 6.5.2

	fno = SPI_fnumber(rulettc, "is_instead");
	is_instead = (bool) SPI_getbinval(ruletup, rulettc, fno, &isnull);

	fno = SPI_fnumber(rulettc, "ev_qual");
	ev_qual = SPI_getvalue(ruletup, rulettc, fno);

	fno = SPI_fnumber(rulettc, "ev_action");
	ev_action = SPI_getvalue(ruletup, rulettc, fno);
	if (ev_action != NULL)
		actions = (List *) stringToNode(ev_action);


	/* ----------
	 * Build the rules definition text
	 * ----------
	 */
	strcpy(buf, "CREATE RULE \"");

	/* The rule name */
	strcat(buf, rulename);
	strcat(buf, "\" AS ON ");

	/* The event the rule is fired for */
	switch (ev_type)
	{
		case '1':
			strcat(buf, "SELECT TO \"");
			break;

		case '2':
			strcat(buf, "UPDATE TO \"");
			break;

		case '3':
			strcat(buf, "INSERT TO \"");
			break;

		case '4':
			strcat(buf, "DELETE TO \"");
			break;

		default:
			elog(ERROR, "get_ruledef: rule %s has unsupported event type %d",
				 rulename, ev_type);
			break;
	}

	/* The relation the rule is fired on */
	strcat(buf, get_relation_name(ev_class));
	strcat(buf, "\"");
	if (ev_attr > 0)
	{
		strcat(buf, ".\"");
		strcat(buf, get_attribute_name(ev_class, ev_attr));
		strcat(buf, "\"");
	}

	/* If the rule has an event qualification, add it */
	if (ev_qual == NULL)
		ev_qual = "";
	if (strlen(ev_qual) > 0 && strcmp(ev_qual, "<>") != 0)
	{
		Node	   *qual;
		Query	   *query;
		QryHier		qh;

		qual = stringToNode(ev_qual);
		query = (Query *) lfirst(actions);
		qh.parent = NULL;
		qh.query = query;

		strcat(buf, " WHERE ");
		strcat(buf, get_rule_expr(&qh, 0, qual, TRUE));
	}

	strcat(buf, " DO ");

	/* The INSTEAD keyword (if so) */
	if (is_instead)
		strcat(buf, "INSTEAD ");

	/* Finally the rules actions */
	if (length(actions) > 1)
	{
		List	   *action;
		Query	   *query;

		strcat(buf, "(");
		foreach(action, actions)
		{
			query = (Query *) lfirst(action);
			strcat(buf, get_query_def(query, NULL));
			strcat(buf, "; ");
		}
		strcat(buf, ");");
	}
	else
	{
		if (length(actions) == 0)
		{
			strcat(buf, "NOTHING;");
		}
		else
		{
			Query	   *query;

			query = (Query *) lfirst(actions);
			strcat(buf, get_query_def(query, NULL));
			strcat(buf, ";");
		}
	}

	/* ----------
	 * That's it
	 * ----------
	 */
	return buf;
}


/* ----------
 * make_viewdef			- reconstruct the SELECT part of a
 *				  view rewrite rule
 * ----------
 */
static char *
make_viewdef(HeapTuple ruletup, TupleDesc rulettc)
{
	char		buf[BUFSIZE];
	Query	   *query;
	char		ev_type;
	Oid			ev_class;
	int2		ev_attr;
	bool		is_instead;
	char	   *ev_qual;
	char	   *ev_action;
	List	   *actions = NIL;
	int			fno;
	bool		isnull;

	/* ----------
	 * Get the attribute values from the rules tuple
	 * ----------
	 */
	fno = SPI_fnumber(rulettc, "ev_type");
	ev_type = (char) SPI_getbinval(ruletup, rulettc, fno, &isnull);

	fno = SPI_fnumber(rulettc, "ev_class");
	ev_class = (Oid) SPI_getbinval(ruletup, rulettc, fno, &isnull);

	fno = SPI_fnumber(rulettc, "ev_attr");
	ev_attr = (int2) SPI_getbinval(ruletup, rulettc, fno, &isnull);

	fno = SPI_fnumber(rulettc, "is_instead");
	is_instead = (bool) SPI_getbinval(ruletup, rulettc, fno, &isnull);

	fno = SPI_fnumber(rulettc, "ev_qual");
	ev_qual = SPI_getvalue(ruletup, rulettc, fno);

	fno = SPI_fnumber(rulettc, "ev_action");
	ev_action = SPI_getvalue(ruletup, rulettc, fno);
	if (ev_action != NULL)
		actions = (List *) stringToNode(ev_action);

	if (length(actions) != 1)
		return "Not a view";

	query = (Query *) lfirst(actions);

	if (ev_type != '1' || ev_attr >= 0 || !is_instead || strcmp(ev_qual, "<>"))
		return "Not a view";

	strcpy(buf, get_query_def(query, NULL));
	strcat(buf, ";");

	/* ----------
	 * That's it
	 * ----------
	 */
	return pstrdup(buf);
}


/* ----------
 * get_query_def			- Parse back one action from
 *					  the parsetree in the actions
 *					  list
 * ----------
 */
static char *
get_query_def(Query *query, QryHier *parentqh)
{
	QryHier		qh;

	qh.parent = parentqh;
	qh.query = query;

	switch (query->commandType)
	{
		case CMD_SELECT:
			return get_select_query_def(query, &qh);
			break;

		case CMD_UPDATE:
			return get_update_query_def(query, &qh);
			break;

		case CMD_INSERT:
			return get_insert_query_def(query, &qh);
			break;

		case CMD_DELETE:
			return get_delete_query_def(query, &qh);
			break;

		case CMD_NOTHING:
			return "NOTHING";
			break;

		default:
			elog(ERROR, "get_ruledef of %s: query command type %d not implemented yet",
				 rulename, query->commandType);
			break;
	}

	return NULL;
}


/* ----------
 * get_select_query_def			- Parse back a SELECT parsetree
 * ----------
 */
static char *
get_select_query_def(Query *query, QryHier *qh)
{
	char		buf[BUFSIZE];
	char	   *sep;
	TargetEntry *tle;
	RangeTblEntry *rte;
	bool	   *rt_used;
	int			rt_length;
	int			rt_numused = 0;
	bool		rt_constonly = TRUE;
	int			i;
	List	   *l;

	/* ----------
	 * First we need to know which and how many of the
	 * range table entries in the query are used in the target list
	 * or queries qualification
	 * ----------
	 */
	rt_length = length(query->rtable);
	rt_used = palloc(sizeof(bool) * rt_length);
	for (i = 0; i < rt_length; i++)
	{
		if (check_if_rte_used((Node *) (query->targetList), i + 1, 0) ||
			check_if_rte_used(query->qual, i + 1, 0) ||
			check_if_rte_used(query->havingQual, i + 1, 0))
		{
			rt_used[i] = TRUE;
			rt_numused++;
		}
		else
			rt_used[i] = FALSE;
	}

	/* ----------
	 * Now check if any of the used rangetable entries is different
	 * from *NEW* and *CURRENT*. If so we must omit the FROM clause
	 * later.
	 * ----------
	 */
	i = 0;
	foreach(l, query->rtable)
	{
		if (!rt_used[i++])
			continue;

		rte = (RangeTblEntry *) lfirst(l);
		if (!strcmp(rte->refname, "*NEW*"))
			continue;
		if (!strcmp(rte->refname, "*CURRENT*"))
			continue;

		rt_constonly = FALSE;
		break;
	}

	/* ----------
	 * Build up the query string - first we say SELECT
	 * ----------
	 */
	strcpy(buf, "SELECT");

	/* Then we tell what to select (the targetlist) */
	sep = " ";
	foreach(l, query->targetList)
	{
		bool		tell_as = FALSE;

		tle = (TargetEntry *) lfirst(l);
		strcat(buf, sep);
		sep = ", ";

		strcat(buf, get_tle_expr(qh, 0, tle, (rt_numused > 1)));

		/* Check if we must say AS ... */
		if (! IsA(tle->expr, Var))
			tell_as = strcmp(tle->resdom->resname, "?column?");
		else
		{
			Var		   *var = (Var *) (tle->expr);
			char	   *attname;

			rte = get_rte_for_var(var, qh);
			attname = get_attribute_name(rte->relid, var->varattno);
			if (strcmp(attname, tle->resdom->resname))
				tell_as = TRUE;
		}

		/* and do if so */
		if (tell_as)
		{
			strcat(buf, " AS \"");
			strcat(buf, tle->resdom->resname);
			strcat(buf, "\"");
		}
	}

	/* If we need other tables that *NEW* or *CURRENT* add the FROM clause */
	if (!rt_constonly && rt_numused > 0)
	{
		strcat(buf, " FROM");

		i = 0;
		sep = " ";
		foreach(l, query->rtable)
		{
			if (rt_used[i++])
			{
				rte = (RangeTblEntry *) lfirst(l);

				if (!strcmp(rte->refname, "*NEW*"))
					continue;

				if (!strcmp(rte->refname, "*CURRENT*"))
					continue;

				strcat(buf, sep);
				sep = ", ";
				strcat(buf, "\"");
				strcat(buf, rte->relname);
				strcat(buf, "\"");
				if (strcmp(rte->relname, rte->refname) != 0)
				{
					strcat(buf, " \"");
					strcat(buf, rte->refname);
					strcat(buf, "\"");
				}
			}
		}
	}

	/* Add the WHERE clause if given */
	if (query->qual != NULL)
	{
		strcat(buf, " WHERE ");
		strcat(buf, get_rule_expr(qh, 0, query->qual, (rt_numused > 1)));
	}

	/* Add the GROUP BY CLAUSE */
	if (query->groupClause != NULL)
	{
		strcat(buf, " GROUP BY ");
		sep = "";
		foreach(l, query->groupClause)
		{
			GroupClause *grp = (GroupClause *) lfirst(l);
			Node *groupexpr;

			groupexpr = (Node *) get_groupclause_expr(grp,
													  query->targetList);
			strcat(buf, sep);
			strcat(buf, get_rule_expr(qh, 0, groupexpr, (rt_numused > 1)));
			sep = ", ";
		}
	}

	/* ----------
	 * Copy the query string into allocated space and return it
	 * ----------
	 */
	return pstrdup(buf);
}


/* ----------
 * get_insert_query_def			- Parse back an INSERT parsetree
 * ----------
 */
static char *
get_insert_query_def(Query *query, QryHier *qh)
{
	char		buf[BUFSIZE];
	char	   *sep;
	TargetEntry *tle;
	RangeTblEntry *rte;
	bool	   *rt_used;
	int			rt_length;
	int			rt_numused = 0;
	bool		rt_constonly = TRUE;
	int			i;
	List	   *l;

	/* ----------
	 * We need to know if other tables than *NEW* or *CURRENT*
	 * are used in the query. If not, it's an INSERT ... VALUES,
	 * otherwise an INSERT ... SELECT.
	 * ----------
	 */
	rt_length = length(query->rtable);
	rt_used = palloc(sizeof(bool) * rt_length);
	for (i = 0; i < rt_length; i++)
	{
		if (check_if_rte_used((Node *) (query->targetList), i + 1, 0) ||
			check_if_rte_used(query->qual, i + 1, 0) ||
			check_if_rte_used(query->havingQual, i + 1, 0))
		{
			rt_used[i] = TRUE;
			rt_numused++;
		}
		else
			rt_used[i] = FALSE;
	}

	i = 0;
	foreach(l, query->rtable)
	{
		if (!rt_used[i++])
			continue;

		rte = (RangeTblEntry *) lfirst(l);
		if (!strcmp(rte->refname, "*NEW*"))
			continue;
		if (!strcmp(rte->refname, "*CURRENT*"))
			continue;

		rt_constonly = FALSE;
		break;
	}

	/* ----------
	 * Start the query with INSERT INTO relname
	 * ----------
	 */
	rte = (RangeTblEntry *) nth(query->resultRelation - 1, query->rtable);
	strcpy(buf, "INSERT INTO \"");
	strcat(buf, rte->relname);
	strcat(buf, "\"");

	/* Add the target list */
	sep = " (";
	foreach(l, query->targetList)
	{
		tle = (TargetEntry *) lfirst(l);

		strcat(buf, sep);
		sep = ", ";
		strcat(buf, "\"");
		strcat(buf, tle->resdom->resname);
		strcat(buf, "\"");
	}
	strcat(buf, ") ");

	/* Add the VALUES or the SELECT */
	if (rt_constonly && query->qual == NULL)
	{
		strcat(buf, "VALUES (");
		sep = "";
		foreach(l, query->targetList)
		{
			tle = (TargetEntry *) lfirst(l);

			strcat(buf, sep);
			sep = ", ";
			strcat(buf, get_tle_expr(qh, 0, tle, (rt_numused > 1)));
		}
		strcat(buf, ")");
	}
	else
		strcat(buf, get_select_query_def(query, qh));

	/* ----------
	 * Copy the query string into allocated space and return it
	 * ----------
	 */
	return pstrdup(buf);
}


/* ----------
 * get_update_query_def			- Parse back an UPDATE parsetree
 * ----------
 */
static char *
get_update_query_def(Query *query, QryHier *qh)
{
	char		buf[BUFSIZE];
	char	   *sep;
	TargetEntry *tle;
	RangeTblEntry *rte;
	List	   *l;

	/* ----------
	 * Start the query with UPDATE relname SET
	 * ----------
	 */
	rte = (RangeTblEntry *) nth(query->resultRelation - 1, query->rtable);
	strcpy(buf, "UPDATE ");
	strcat(buf, rte->relname);
	strcat(buf, " SET ");

	/* Add the comma separated list of 'attname = value' */
	sep = "";
	foreach(l, query->targetList)
	{
		tle = (TargetEntry *) lfirst(l);

		strcat(buf, sep);
		sep = ", ";
		strcat(buf, "\"");
		strcat(buf, tle->resdom->resname);
		strcat(buf, "\" = ");
		strcat(buf, get_tle_expr(qh, query->resultRelation,
								 tle, TRUE));
	}

	/* Finally add a WHERE clause if given */
	if (query->qual != NULL)
	{
		strcat(buf, " WHERE ");
		strcat(buf, get_rule_expr(qh, query->resultRelation,
								  query->qual, TRUE));
	}

	/* ----------
	 * Copy the query string into allocated space and return it
	 * ----------
	 */
	return pstrdup(buf);
}


/* ----------
 * get_delete_query_def			- Parse back a DELETE parsetree
 * ----------
 */
static char *
get_delete_query_def(Query *query, QryHier *qh)
{
	char		buf[BUFSIZE];
	RangeTblEntry *rte;

	/* ----------
	 * Start the query with DELETE FROM relname
	 * ----------
	 */
	rte = (RangeTblEntry *) nth(query->resultRelation - 1, query->rtable);
	strcpy(buf, "DELETE FROM \"");
	strcat(buf, rte->relname);
	strcat(buf, "\"");

	/* Add a WHERE clause if given */
	if (query->qual != NULL)
	{
		strcat(buf, " WHERE ");
		strcat(buf, get_rule_expr(qh, 0, query->qual, FALSE));
	}

	/* ----------
	 * Copy the query string into allocated space and return it
	 * ----------
	 */
	return pstrdup(buf);
}

/*
 * Find the RTE referenced by a (possibly nonlocal) Var.
 */
static RangeTblEntry *
get_rte_for_var(Var *var, QryHier *qh)
{
	int		sup = var->varlevelsup;

	while (sup-- > 0)
		qh = qh->parent;

	return (RangeTblEntry *) nth(var->varno - 1, qh->query->rtable);
}


/* ----------
 * get_rule_expr			- Parse back an expression
 * ----------
 */
static char *
get_rule_expr(QryHier *qh, int rt_index, Node *node, bool varprefix)
{
	char		buf[BUFSIZE];

	if (node == NULL)