ruleutils.c

来自「PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统」· C语言 代码 · 共 2,434 行 · 第 1/5 页

 *
 * The returned node is actually the given RangeTblEntry, but we declare it
 * as just Node to discourage callers from assuming anything.
 */
Node *
deparse_context_for_rte(RangeTblEntry *rte)
{
	return (Node *) rte;
}

/*
 * deparse_context_for_subplan	- Build deparse context for a plan node
 *
 * Helper routine to build one of the inputs for deparse_context_for_plan.
 * Pass the tlist of the subplan node, plus the query rangetable.
 *
 * The returned node is actually a RangeTblEntry, but we declare it as just
 * Node to discourage callers from assuming anything.
 */
Node *
deparse_context_for_subplan(const char *name, List *tlist,
							List *rtable)
{
	RangeTblEntry *rte = makeNode(RangeTblEntry);
	List	   *attrs = NIL;
	int			nattrs = 0;
	int			rtablelength = list_length(rtable);
	ListCell   *tl;
	char		buf[32];

	foreach(tl, tlist)
	{
		TargetEntry *tle = lfirst(tl);

		nattrs++;
		Assert(tle->resno == nattrs);
		if (tle->resname)
		{
			attrs = lappend(attrs, makeString(tle->resname));
			continue;
		}
		if (tle->expr && IsA(tle->expr, Var))
		{
			Var		   *var = (Var *) tle->expr;

			/* varno/varattno won't be any good, but varnoold might be */
			if (var->varnoold > 0 && var->varnoold <= rtablelength)
			{
				RangeTblEntry *varrte = rt_fetch(var->varnoold, rtable);
				AttrNumber	varattnum = var->varoattno;

				/* need this test in case it's referencing a resjunk col */
				if (varattnum <= list_length(varrte->eref->colnames))
				{
					char	   *varname;

					varname = get_rte_attribute_name(varrte, varattnum);
					attrs = lappend(attrs, makeString(varname));
					continue;
				}
			}
		}
		/* Fallback if can't get name */
		snprintf(buf, sizeof(buf), "?column%d?", tle->resno);
		attrs = lappend(attrs, makeString(pstrdup(buf)));
	}

	/*
	 * We create an RTE_SPECIAL RangeTblEntry, and store the given tlist
	 * in its coldeflist field.  This is a hack to make the tlist available
	 * to get_name_for_var_field().  RTE_SPECIAL nodes shouldn't appear in
	 * deparse contexts otherwise.
	 */
	rte->rtekind = RTE_SPECIAL;
	rte->relid = InvalidOid;
	rte->coldeflist = tlist;
	rte->eref = makeAlias(name, attrs);
	rte->inh = false;
	rte->inFromCl = true;

	return (Node *) rte;
}

/* ----------
 * make_ruledef			- reconstruct the CREATE RULE command
 *				  for a given pg_rewrite tuple
 * ----------
 */
static void
make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
			 int prettyFlags)
{
	char	   *rulename;
	char		ev_type;
	Oid			ev_class;
	int2		ev_attr;
	bool		is_instead;
	char	   *ev_qual;
	char	   *ev_action;
	List	   *actions = NIL;
	int			fno;
	Datum		dat;
	bool		isnull;

	/*
	 * Get the attribute values from the rules tuple
	 */
	fno = SPI_fnumber(rulettc, "rulename");
	dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
	Assert(!isnull);
	rulename = NameStr(*(DatumGetName(dat)));

	fno = SPI_fnumber(rulettc, "ev_type");
	dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
	Assert(!isnull);
	ev_type = DatumGetChar(dat);

	fno = SPI_fnumber(rulettc, "ev_class");
	dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
	Assert(!isnull);
	ev_class = DatumGetObjectId(dat);

	fno = SPI_fnumber(rulettc, "ev_attr");
	dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
	Assert(!isnull);
	ev_attr = DatumGetInt16(dat);

	fno = SPI_fnumber(rulettc, "is_instead");
	dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
	Assert(!isnull);
	is_instead = DatumGetBool(dat);

	/* these could be nulls */
	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
	 */
	appendStringInfo(buf, "CREATE RULE %s AS",
					 quote_identifier(rulename));

	if (prettyFlags & PRETTYFLAG_INDENT)
		appendStringInfoString(buf, "\n    ON ");
	else
		appendStringInfoString(buf, " ON ");

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

		case '2':
			appendStringInfo(buf, "UPDATE");
			break;

		case '3':
			appendStringInfo(buf, "INSERT");
			break;

		case '4':
			appendStringInfo(buf, "DELETE");
			break;

		default:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("rule \"%s\" has unsupported event type %d",
							rulename, ev_type)));
			break;
	}

	/* The relation the rule is fired on */
	appendStringInfo(buf, " TO %s", generate_relation_name(ev_class));
	if (ev_attr > 0)
		appendStringInfo(buf, ".%s",
						 quote_identifier(get_relid_attribute_name(ev_class,
																   ev_attr)));

	/* 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;
		deparse_context context;
		deparse_namespace dpns;

		if (prettyFlags & PRETTYFLAG_INDENT)
			appendStringInfoString(buf, "\n  ");
		appendStringInfo(buf, " WHERE ");

		qual = stringToNode(ev_qual);

		/*
		 * We need to make a context for recognizing any Vars in the qual
		 * (which can only be references to OLD and NEW).  Use the rtable of
		 * the first query in the action list for this purpose.
		 */
		query = (Query *) linitial(actions);

		/*
		 * If the action is INSERT...SELECT, OLD/NEW have been pushed down
		 * into the SELECT, and that's what we need to look at. (Ugly kluge
		 * ... try to fix this when we redesign querytrees.)
		 */
		query = getInsertSelectQuery(query, NULL);

		/* Must acquire locks right away; see notes in get_query_def() */
		AcquireRewriteLocks(query);

		context.buf = buf;
		context.namespaces = list_make1(&dpns);
		context.varprefix = (list_length(query->rtable) != 1);
		context.prettyFlags = prettyFlags;
		context.indentLevel = PRETTYINDENT_STD;
		dpns.rtable = query->rtable;
		dpns.outer_varno = dpns.inner_varno = 0;
		dpns.outer_rte = dpns.inner_rte = NULL;

		get_rule_expr(qual, &context, false);
	}

	appendStringInfo(buf, " DO ");

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

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

		appendStringInfo(buf, "(");
		foreach(action, actions)
		{
			query = (Query *) lfirst(action);
			get_query_def(query, buf, NIL, NULL, prettyFlags, 0);
			if (prettyFlags)
				appendStringInfo(buf, ";\n");
			else
				appendStringInfo(buf, "; ");
		}
		appendStringInfo(buf, ");");
	}
	else if (list_length(actions) == 0)
	{
		appendStringInfo(buf, "NOTHING;");
	}
	else
	{
		Query	   *query;

		query = (Query *) linitial(actions);
		get_query_def(query, buf, NIL, NULL, prettyFlags, 0);
		appendStringInfo(buf, ";");
	}
}


/* ----------
 * make_viewdef			- reconstruct the SELECT part of a
 *				  view rewrite rule
 * ----------
 */
static void
make_viewdef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
			 int prettyFlags)
{
	Query	   *query;
	char		ev_type;
	Oid			ev_class;
	int2		ev_attr;
	bool		is_instead;
	char	   *ev_qual;
	char	   *ev_action;
	List	   *actions = NIL;
	Relation	ev_relation;
	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 (list_length(actions) != 1)
	{
		appendStringInfo(buf, "Not a view");
		return;
	}

	query = (Query *) linitial(actions);

	if (ev_type != '1' || ev_attr >= 0 || !is_instead ||
		strcmp(ev_qual, "<>") != 0 || query->commandType != CMD_SELECT)
	{
		appendStringInfo(buf, "Not a view");
		return;
	}

	ev_relation = heap_open(ev_class, AccessShareLock);

	get_query_def(query, buf, NIL, RelationGetDescr(ev_relation),
				  prettyFlags, 0);
	appendStringInfo(buf, ";");

	heap_close(ev_relation, AccessShareLock);
}


/* ----------
 * get_query_def			- Parse back one query parsetree
 *
 * If resultDesc is not NULL, then it is the output tuple descriptor for
 * the view represented by a SELECT query.
 * ----------
 */
static void
get_query_def(Query *query, StringInfo buf, List *parentnamespace,
			  TupleDesc resultDesc, int prettyFlags, int startIndent)
{
	deparse_context context;
	deparse_namespace dpns;

	/*
	 * Before we begin to examine the query, acquire locks on referenced
	 * relations, and fix up deleted columns in JOIN RTEs.	This ensures
	 * consistent results.	Note we assume it's OK to scribble on the passed
	 * querytree!
	 */
	AcquireRewriteLocks(query);

	context.buf = buf;
	context.namespaces = lcons(&dpns, list_copy(parentnamespace));
	context.varprefix = (parentnamespace != NIL ||
						 list_length(query->rtable) != 1);
	context.prettyFlags = prettyFlags;
	context.indentLevel = startIndent;

	dpns.rtable = query->rtable;
	dpns.outer_varno = dpns.inner_varno = 0;
	dpns.outer_rte = dpns.inner_rte = NULL;

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

		case CMD_UPDATE:
			get_update_query_def(query, &context);
			break;

		case CMD_INSERT:
			get_insert_query_def(query, &context);
			break;

		case CMD_DELETE:
			get_delete_query_def(query, &context);
			break;

		case CMD_NOTHING:
			appendStringInfo(buf, "NOTHING");
			break;

		case CMD_UTILITY:
			get_utility_query_def(query, &context);
			break;

		default:
			elog(ERROR, "unrecognized query command type: %d",
				 query->commandType);
			break;
	}
}


/* ----------
 * get_select_query_def			- Parse back a SELECT parsetree
 * ----------
 */
static void
get_select_query_def(Query *query, deparse_context *context,
					 TupleDesc resultDesc)
{
	StringInfo	buf = context->buf;
	bool		force_colno;
	char	   *sep;
	ListCell   *l;

	/*
	 * If the Query node has a setOperations tree, then it's the top level of
	 * a UNION/INTERSECT/EXCEPT query; only the ORDER BY and LIMIT fields are
	 * interesting in the top query itself.
	 */
	if (query->setOperations)
	{
		get_setop_query(query->setOperations, query, context, resultDesc);
		/* ORDER BY clauses must be simple in this case */
		force_colno = true;
	}
	else
	{
		get_basic_select_query(query, context, resultDesc);
		force_colno = false;
	}

	/* Add the ORDER BY clause if given */
	if (query->sortClause != NIL)
	{
		appendContextKeyword(context, " ORDER BY ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
		sep = "";
		foreach(l, query->sortClause)
		{
			SortClause *srt = (SortClause *) lfirst(l);
			Node	   *sortexpr;
			Oid			sortcoltype;
			TypeCacheEntry *typentry;

			appendStringInfoString(buf, sep);
			sortexpr = get_rule_sortgroupclause(srt, query->targetList,
												force_colno, context);
			sortcoltype = exprType(sortexpr);
			/* See whether operator is default < or > for datatype */
			typentry = lookup_type_cache(sortcoltype,
										 TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
			if (srt->sortop == typentry->lt_opr)
				 /* ASC is default, so emit nothing */ ;
			else if (srt->sortop == typentry->gt_opr)
				appendStringInfo(buf, " DESC");
			else
				appendStringInfo(buf, " USING %s",
								 generate_operator_name(srt->sortop,
														sortcoltype,
														sortcoltype));
			sep = ", ";
		}
	}

	/* Add the LIMIT clause if given */
	if (query->limitOffset != NULL)
	{
		appendContextKeyword(context, " OFFSET ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
		get_rule_expr(query->limitOffset, context, false);
	}
	if (query->limitCount != NULL)
	{
		appendContextKeyword(context, " LIMIT ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
		if (IsA(query->limitCount, Const) &&
			((Const *) query->limitCount)->constisnull)
			appendStringInfo(buf, "ALL");
		else
			get_rule_expr(query->limitCount, context, false);
	}