parse_relation.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

 *
 * "*" is returned if the given attnum is InvalidAttrNumber --- this case
 * occurs when a Var represents a whole tuple of a relation.
 */
char *
get_rte_attribute_name(RangeTblEntry *rte, AttrNumber attnum)
{
	if (attnum == InvalidAttrNumber)
		return "*";

	/*
	 * If there is a user-written column alias, use it.
	 */
	if (rte->alias &&
		attnum > 0 && attnum <= list_length(rte->alias->colnames))
		return strVal(list_nth(rte->alias->colnames, attnum - 1));

	/*
	 * If the RTE is a relation, go to the system catalogs not the
	 * eref->colnames list.  This is a little slower but it will give the
	 * right answer if the column has been renamed since the eref list was
	 * built (which can easily happen for rules).
	 */
	if (rte->rtekind == RTE_RELATION)
		return get_relid_attribute_name(rte->relid, attnum);

	/*
	 * Otherwise use the column name from eref.  There should always be one.
	 */
	if (attnum > 0 && attnum <= list_length(rte->eref->colnames))
		return strVal(list_nth(rte->eref->colnames, attnum - 1));

	/* else caller gave us a bogus attnum */
	elog(ERROR, "invalid attnum %d for rangetable entry %s",
		 attnum, rte->eref->aliasname);
	return NULL;				/* keep compiler quiet */
}

/*
 * get_rte_attribute_type
 *		Get attribute type information from a RangeTblEntry
 */
void
get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
					   Oid *vartype, int32 *vartypmod)
{
	switch (rte->rtekind)
	{
		case RTE_RELATION:
			{
				/* Plain relation RTE --- get the attribute's type info */
				HeapTuple	tp;
				Form_pg_attribute att_tup;

				tp = SearchSysCache(ATTNUM,
									ObjectIdGetDatum(rte->relid),
									Int16GetDatum(attnum),
									0, 0);
				if (!HeapTupleIsValid(tp))		/* shouldn't happen */
					elog(ERROR, "cache lookup failed for attribute %d of relation %u",
						 attnum, rte->relid);
				att_tup = (Form_pg_attribute) GETSTRUCT(tp);

				/*
				 * If dropped column, pretend it ain't there.  See notes in
				 * scanRTEForColumn.
				 */
				if (att_tup->attisdropped)
					ereport(ERROR,
							(errcode(ERRCODE_UNDEFINED_COLUMN),
					errmsg("column \"%s\" of relation \"%s\" does not exist",
						   NameStr(att_tup->attname),
						   get_rel_name(rte->relid))));
				*vartype = att_tup->atttypid;
				*vartypmod = att_tup->atttypmod;
				ReleaseSysCache(tp);
			}
			break;
		case RTE_SUBQUERY:
			{
				/* Subselect RTE --- get type info from subselect's tlist */
				TargetEntry *te = get_tle_by_resno(rte->subquery->targetList,
												   attnum);

				if (te == NULL || te->resjunk)
					elog(ERROR, "subquery %s does not have attribute %d",
						 rte->eref->aliasname, attnum);
				*vartype = exprType((Node *) te->expr);
				*vartypmod = exprTypmod((Node *) te->expr);
			}
			break;
		case RTE_FUNCTION:
			{
				/* Function RTE */
				TypeFuncClass functypclass;
				Oid			funcrettype;
				TupleDesc	tupdesc;

				functypclass = get_expr_result_type(rte->funcexpr,
													&funcrettype,
													&tupdesc);

				if (functypclass == TYPEFUNC_COMPOSITE)
				{
					/* Composite data type, e.g. a table's row type */
					Form_pg_attribute att_tup;

					Assert(tupdesc);
					/* this is probably a can't-happen case */
					if (attnum < 1 || attnum > tupdesc->natts)
						ereport(ERROR,
								(errcode(ERRCODE_UNDEFINED_COLUMN),
						errmsg("column %d of relation \"%s\" does not exist",
							   attnum,
							   rte->eref->aliasname)));

					att_tup = tupdesc->attrs[attnum - 1];

					/*
					 * If dropped column, pretend it ain't there.  See notes
					 * in scanRTEForColumn.
					 */
					if (att_tup->attisdropped)
						ereport(ERROR,
								(errcode(ERRCODE_UNDEFINED_COLUMN),
								 errmsg("column \"%s\" of relation \"%s\" does not exist",
										NameStr(att_tup->attname),
										rte->eref->aliasname)));
					*vartype = att_tup->atttypid;
					*vartypmod = att_tup->atttypmod;
				}
				else if (functypclass == TYPEFUNC_SCALAR)
				{
					/* Base data type, i.e. scalar */
					*vartype = funcrettype;
					*vartypmod = -1;
				}
				else if (functypclass == TYPEFUNC_RECORD)
				{
					ColumnDef  *colDef = list_nth(rte->coldeflist, attnum - 1);

					*vartype = typenameTypeId(colDef->typename);
					*vartypmod = colDef->typename->typmod;
				}
				else
				{
					/* addRangeTableEntryForFunction should've caught this */
					elog(ERROR, "function in FROM has unsupported return type");
				}
			}
			break;
		case RTE_JOIN:
			{
				/*
				 * Join RTE --- get type info from join RTE's alias variable
				 */
				Node	   *aliasvar;

				Assert(attnum > 0 && attnum <= list_length(rte->joinaliasvars));
				aliasvar = (Node *) list_nth(rte->joinaliasvars, attnum - 1);
				*vartype = exprType(aliasvar);
				*vartypmod = exprTypmod(aliasvar);
			}
			break;
		default:
			elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
	}
}

/*
 * get_rte_attribute_is_dropped
 *		Check whether attempted attribute ref is to a dropped column
 */
bool
get_rte_attribute_is_dropped(RangeTblEntry *rte, AttrNumber attnum)
{
	bool		result;

	switch (rte->rtekind)
	{
		case RTE_RELATION:
			{
				/*
				 * Plain relation RTE --- get the attribute's catalog entry
				 */
				HeapTuple	tp;
				Form_pg_attribute att_tup;

				tp = SearchSysCache(ATTNUM,
									ObjectIdGetDatum(rte->relid),
									Int16GetDatum(attnum),
									0, 0);
				if (!HeapTupleIsValid(tp))		/* shouldn't happen */
					elog(ERROR, "cache lookup failed for attribute %d of relation %u",
						 attnum, rte->relid);
				att_tup = (Form_pg_attribute) GETSTRUCT(tp);
				result = att_tup->attisdropped;
				ReleaseSysCache(tp);
			}
			break;
		case RTE_SUBQUERY:
			/* Subselect RTEs never have dropped columns */
			result = false;
			break;
		case RTE_JOIN:
			{
				/*
				 * A join RTE would not have dropped columns when constructed,
				 * but one in a stored rule might contain columns that were
				 * dropped from the underlying tables, if said columns are
				 * nowhere explicitly referenced in the rule.  This will be
				 * signaled to us by a NULL Const in the joinaliasvars list.
				 */
				Var		   *aliasvar;

				if (attnum <= 0 ||
					attnum > list_length(rte->joinaliasvars))
					elog(ERROR, "invalid varattno %d", attnum);
				aliasvar = (Var *) list_nth(rte->joinaliasvars, attnum - 1);

				result = IsA(aliasvar, Const);
			}
			break;
		case RTE_FUNCTION:
			{
				/* Function RTE */
				Oid			funcrettype = exprType(rte->funcexpr);
				Oid			funcrelid = typeidTypeRelid(funcrettype);

				if (OidIsValid(funcrelid))
				{
					/*
					 * Composite data type, i.e. a table's row type
					 *
					 * Same as ordinary relation RTE
					 */
					HeapTuple	tp;
					Form_pg_attribute att_tup;

					tp = SearchSysCache(ATTNUM,
										ObjectIdGetDatum(funcrelid),
										Int16GetDatum(attnum),
										0, 0);
					if (!HeapTupleIsValid(tp))	/* shouldn't happen */
						elog(ERROR, "cache lookup failed for attribute %d of relation %u",
							 attnum, funcrelid);
					att_tup = (Form_pg_attribute) GETSTRUCT(tp);
					result = att_tup->attisdropped;
					ReleaseSysCache(tp);
				}
				else
				{
					/*
					 * Must be a base data type, i.e. scalar
					 */
					result = false;
				}
			}
			break;
		default:
			elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
			result = false;		/* keep compiler quiet */
	}

	return result;
}

/*
 * Given a targetlist and a resno, return the matching TargetEntry
 *
 * Returns NULL if resno is not present in list.
 *
 * Note: we need to search, rather than just indexing with list_nth(),
 * because not all tlists are sorted by resno.
 */
TargetEntry *
get_tle_by_resno(List *tlist, AttrNumber resno)
{
	ListCell   *l;

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

		if (tle->resno == resno)
			return tle;
	}
	return NULL;
}

/*
 *	given relation and att name, return id of variable
 *
 *	This should only be used if the relation is already
 *	heap_open()'ed.  Use the cache version get_attnum()
 *	for access to non-opened relations.
 */
int
attnameAttNum(Relation rd, const char *attname, bool sysColOK)
{
	int			i;

	for (i = 0; i < rd->rd_rel->relnatts; i++)
	{
		Form_pg_attribute att = rd->rd_att->attrs[i];

		if (namestrcmp(&(att->attname), attname) == 0 && !att->attisdropped)
			return i + 1;
	}

	if (sysColOK)
	{
		if ((i = specialAttNum(attname)) != InvalidAttrNumber)
		{
			if (i != ObjectIdAttributeNumber || rd->rd_rel->relhasoids)
				return i;
		}
	}

	/* on failure */
	ereport(ERROR,
			(errcode(ERRCODE_UNDEFINED_COLUMN),
			 errmsg("column \"%s\" of relation \"%s\" does not exist",
					attname, RelationGetRelationName(rd))));
	return InvalidAttrNumber;	/* keep compiler quiet */
}

/* specialAttNum()
 *
 * Check attribute name to see if it is "special", e.g. "oid".
 * - thomas 2000-02-07
 *
 * Note: this only discovers whether the name could be a system attribute.
 * Caller needs to verify that it really is an attribute of the rel,
 * at least in the case of "oid", which is now optional.
 */
static int
specialAttNum(const char *attname)
{
	Form_pg_attribute sysatt;

	sysatt = SystemAttributeByName(attname,
								   true /* "oid" will be accepted */ );
	if (sysatt != NULL)
		return sysatt->attnum;
	return InvalidAttrNumber;
}


/*
 * given attribute id, return name of that attribute
 *
 *	This should only be used if the relation is already
 *	heap_open()'ed.  Use the cache version get_atttype()
 *	for access to non-opened relations.
 */
Name
attnumAttName(Relation rd, int attid)
{
	if (attid <= 0)
	{
		Form_pg_attribute sysatt;

		sysatt = SystemAttributeDefinition(attid, rd->rd_rel->relhasoids);
		return &sysatt->attname;
	}
	if (attid > rd->rd_att->natts)
		elog(ERROR, "invalid attribute number %d", attid);
	return &rd->rd_att->attrs[attid - 1]->attname;
}

/*
 * given attribute id, return type of that attribute
 *
 *	This should only be used if the relation is already
 *	heap_open()'ed.  Use the cache version get_atttype()
 *	for access to non-opened relations.
 */
Oid
attnumTypeId(Relation rd, int attid)
{
	if (attid <= 0)
	{
		Form_pg_attribute sysatt;

		sysatt = SystemAttributeDefinition(attid, rd->rd_rel->relhasoids);
		return sysatt->atttypid;
	}
	if (attid > rd->rd_att->natts)
		elog(ERROR, "invalid attribute number %d", attid);
	return rd->rd_att->attrs[attid - 1]->atttypid;
}

/*
 * Generate a warning or error about an implicit RTE, if appropriate.
 *
 * If ADD_MISSING_FROM is not enabled, raise an error. Otherwise, emit
 * a warning.
 */
static void
warnAutoRange(ParseState *pstate, RangeVar *relation)
{
	RangeTblEntry *rte;
	int			sublevels_up;
	const char *badAlias = NULL;

	/*
	 * Check to see if there are any potential matches in the query's
	 * rangetable.  This affects the message we provide.
	 */
	rte = searchRangeTable(pstate, relation);

	/*
	 * If we found a match that has an alias and the alias is visible in
	 * the namespace, then the problem is probably use of the relation's
	 * real name instead of its alias, ie "SELECT foo.* FROM foo f".
	 * This mistake is common enough to justify a specific hint.
	 *
	 * If we found a match that doesn't meet those criteria, assume the
	 * problem is illegal use of a relation outside its scope, as in the
	 * MySQL-ism "SELECT ... FROM a, b LEFT JOIN c ON (a.x = c.y)".
	 */
	if (rte && rte->alias &&
		strcmp(rte->eref->aliasname, relation->relname) != 0 &&
		refnameRangeTblEntry(pstate, NULL, rte->eref->aliasname,
							 &sublevels_up) == rte)
		badAlias = rte->eref->aliasname;

	if (!add_missing_from)
	{
		if (rte)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_TABLE),
					 errmsg("invalid reference to FROM-clause entry for table \"%s\"",
							relation->relname),
					 (badAlias ?
					  errhint("Perhaps you meant to reference the table alias \"%s\".",
							  badAlias) :
					  errhint("There is an entry for table \"%s\", but it cannot be referenced from this part of the query.",
							  rte->eref->aliasname))));
		else
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_TABLE),
					 (pstate->parentParseState ?
					  errmsg("missing FROM-clause entry in subquery for table \"%s\"",
							 relation->relname) :
					  errmsg("missing FROM-clause entry for table \"%s\"",
							 relation->relname))));
	}
	else
	{
		/* just issue a warning */
		ereport(NOTICE,
				(errcode(ERRCODE_UNDEFINED_TABLE),
				 (pstate->parentParseState ?
				  errmsg("adding missing FROM-clause entry in subquery for table \"%s\"",
						 relation->relname) :
				  errmsg("adding missing FROM-clause entry for table \"%s\"",
						 relation->relname)),
				 (badAlias ?
				  errhint("Perhaps you meant to reference the table alias \"%s\".",
						  badAlias) :
				  (rte ?
				   errhint("There is an entry for table \"%s\", but it cannot be referenced from this part of the query.",
						   rte->eref->aliasname) : 0))));
	}
}