parse_relation.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 1,944 行 · 第 1/4 页

	 */
	if (result)
		return result;

	/*
	 * If the RTE represents a real table, consider system column names.
	 */
	if (rte->rtekind == RTE_RELATION)
	{
		/* quick check to see if name could be a system column */
		attnum = specialAttNum(colname);
		if (attnum != InvalidAttrNumber)
		{
			/* now check to see if column actually is defined */
			if (SearchSysCacheExists(ATTNUM,
									 ObjectIdGetDatum(rte->relid),
									 Int16GetDatum(attnum),
									 0, 0))
			{
				result = (Node *) make_var(pstate, rte, attnum);
				rte->checkForRead = true;
			}
		}
	}

	return result;
}

/*
 * colNameToVar
 *	  Search for an unqualified column name.
 *	  If found, return the appropriate Var node (or expression).
 *	  If not found, return NULL.  If the name proves ambiguous, raise error.
 *	  If localonly is true, only names in the innermost query are considered.
 */
Node *
colNameToVar(ParseState *pstate, char *colname, bool localonly)
{
	Node	   *result = NULL;
	ParseState *orig_pstate = pstate;
	int			levels_up = 0;

	while (pstate != NULL)
	{
		List	   *ns;

		/*
		 * We need to look only at top-level namespace items, and even for
		 * those, ignore RTEs that are marked as not inFromCl and not the
		 * query's target relation.
		 */
		foreach(ns, pstate->p_namespace)
		{
			Node	   *nsnode = (Node *) lfirst(ns);
			Node	   *newresult = NULL;

			if (IsA(nsnode, RangeTblRef))
			{
				int			varno = ((RangeTblRef *) nsnode)->rtindex;
				RangeTblEntry *rte = rt_fetch(varno, pstate->p_rtable);

				if (!rte->inFromCl &&
					rte != pstate->p_target_rangetblentry)
					continue;

				/* use orig_pstate here to get the right sublevels_up */
				newresult = scanRTEForColumn(orig_pstate, rte, colname);
			}
			else if (IsA(nsnode, JoinExpr))
			{
				int			varno = ((JoinExpr *) nsnode)->rtindex;
				RangeTblEntry *rte = rt_fetch(varno, pstate->p_rtable);

				/* joins are always inFromCl, so no need to check */

				/* use orig_pstate here to get the right sublevels_up */
				newresult = scanRTEForColumn(orig_pstate, rte, colname);
			}
			else
				elog(ERROR, "unrecognized node type: %d",
					 (int) nodeTag(nsnode));

			if (newresult)
			{
				if (result)
					ereport(ERROR,
							(errcode(ERRCODE_AMBIGUOUS_COLUMN),
						   errmsg("column reference \"%s\" is ambiguous",
								  colname)));
				result = newresult;
			}
		}

		if (result != NULL || localonly)
			break;				/* found, or don't want to look at parent */

		pstate = pstate->parentParseState;
		levels_up++;
	}

	return result;
}

/*
 * qualifiedNameToVar
 *	  Search for a qualified column name: either refname.colname or
 *	  schemaname.relname.colname.
 *
 *	  If found, return the appropriate Var node.
 *	  If not found, return NULL.  If the name proves ambiguous, raise error.
 */
Node *
qualifiedNameToVar(ParseState *pstate,
				   char *schemaname,
				   char *refname,
				   char *colname,
				   bool implicitRTEOK)
{
	RangeTblEntry *rte;
	int			sublevels_up;

	rte = refnameRangeTblEntry(pstate, schemaname, refname, &sublevels_up);

	if (rte == NULL)
	{
		if (!implicitRTEOK)
			return NULL;
		rte = addImplicitRTE(pstate, makeRangeVar(schemaname, refname));
	}

	return scanRTEForColumn(pstate, rte, colname);
}

/*
 * Add an entry for a relation to the pstate's range table (p_rtable).
 *
 * If pstate is NULL, we just build an RTE and return it without adding it
 * to an rtable list.
 *
 * Note: formerly this checked for refname conflicts, but that's wrong.
 * Caller is responsible for checking for conflicts in the appropriate scope.
 */
RangeTblEntry *
addRangeTableEntry(ParseState *pstate,
				   RangeVar *relation,
				   Alias *alias,
				   bool inh,
				   bool inFromCl)
{
	RangeTblEntry *rte = makeNode(RangeTblEntry);
	char	   *refname = alias ? alias->aliasname : relation->relname;
	LOCKMODE	lockmode;
	Relation	rel;
	Alias	   *eref;
	int			maxattrs;
	int			numaliases;
	int			varattno;

	rte->rtekind = RTE_RELATION;
	rte->alias = alias;

	/*
	 * Get the rel's OID.  This access also ensures that we have an
	 * up-to-date relcache entry for the rel.  Since this is typically the
	 * first access to a rel in a statement, be careful to get the right
	 * access level depending on whether we're doing SELECT FOR UPDATE.
	 */
	lockmode = isForUpdate(pstate, refname) ? RowShareLock : AccessShareLock;
	rel = heap_openrv(relation, lockmode);
	rte->relid = RelationGetRelid(rel);

	eref = alias ? (Alias *) copyObject(alias) : makeAlias(refname, NIL);
	numaliases = length(eref->colnames);

	/*
	 * Since the rel is open anyway, let's check that the number of column
	 * aliases is reasonable. - Thomas 2000-02-04
	 */
	maxattrs = RelationGetNumberOfAttributes(rel);
	if (maxattrs < numaliases)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
				 errmsg("table \"%s\" has %d columns available but %d columns specified",
				   RelationGetRelationName(rel), maxattrs, numaliases)));

	/* fill in any unspecified alias columns using actual column names */
	for (varattno = numaliases; varattno < maxattrs; varattno++)
	{
		char	   *attrname;

		attrname = pstrdup(NameStr(rel->rd_att->attrs[varattno]->attname));
		eref->colnames = lappend(eref->colnames, makeString(attrname));
	}
	rte->eref = eref;

	/*
	 * Drop the rel refcount, but keep the access lock till end of
	 * transaction so that the table can't be deleted or have its schema
	 * modified underneath us.
	 */
	heap_close(rel, NoLock);

	/*----------
	 * Flags:
	 * - this RTE should be expanded to include descendant tables,
	 * - this RTE is in the FROM clause,
	 * - this RTE should be checked for read/write access rights.
	 *
	 * The initial default on access checks is always check-for-READ-access,
	 * which is the right thing for all except target tables.
	 *----------
	 */
	rte->inh = inh;
	rte->inFromCl = inFromCl;
	rte->checkForRead = true;
	rte->checkForWrite = false;

	rte->checkAsUser = InvalidOid;		/* not set-uid by default, either */

	/*
	 * Add completed RTE to pstate's range table list, but not to join
	 * list nor namespace --- caller must do that if appropriate.
	 */
	if (pstate != NULL)
		pstate->p_rtable = lappend(pstate->p_rtable, rte);

	return rte;
}

/*
 * Add an entry for a relation to the pstate's range table (p_rtable).
 *
 * This is just like addRangeTableEntry() except that it makes an RTE
 * given a relation OID instead of a RangeVar reference.
 *
 * Note that an alias clause *must* be supplied.
 */
RangeTblEntry *
addRangeTableEntryForRelation(ParseState *pstate,
							  Oid relid,
							  Alias *alias,
							  bool inh,
							  bool inFromCl)
{
	RangeTblEntry *rte = makeNode(RangeTblEntry);
	char	   *refname = alias->aliasname;
	LOCKMODE	lockmode;
	Relation	rel;
	Alias	   *eref;
	int			maxattrs;
	int			numaliases;
	int			varattno;

	rte->rtekind = RTE_RELATION;
	rte->alias = alias;

	/*
	 * Get the rel's relcache entry.  This access ensures that we have an
	 * up-to-date relcache entry for the rel.  Since this is typically the
	 * first access to a rel in a statement, be careful to get the right
	 * access level depending on whether we're doing SELECT FOR UPDATE.
	 */
	lockmode = isForUpdate(pstate, refname) ? RowShareLock : AccessShareLock;
	rel = heap_open(relid, lockmode);
	rte->relid = relid;

	eref = (Alias *) copyObject(alias);
	numaliases = length(eref->colnames);

	/*
	 * Since the rel is open anyway, let's check that the number of column
	 * aliases is reasonable. - Thomas 2000-02-04
	 */
	maxattrs = RelationGetNumberOfAttributes(rel);
	if (maxattrs < numaliases)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
				 errmsg("table \"%s\" has %d columns available but %d columns specified",
				   RelationGetRelationName(rel), maxattrs, numaliases)));

	/* fill in any unspecified alias columns using actual column names */
	for (varattno = numaliases; varattno < maxattrs; varattno++)
	{
		char	   *attrname;

		attrname = pstrdup(NameStr(rel->rd_att->attrs[varattno]->attname));
		eref->colnames = lappend(eref->colnames, makeString(attrname));
	}
	rte->eref = eref;

	/*
	 * Drop the rel refcount, but keep the access lock till end of
	 * transaction so that the table can't be deleted or have its schema
	 * modified underneath us.
	 */
	heap_close(rel, NoLock);

	/*----------
	 * Flags:
	 * - this RTE should be expanded to include descendant tables,
	 * - this RTE is in the FROM clause,
	 * - this RTE should be checked for read/write access rights.
	 *
	 * The initial default on access checks is always check-for-READ-access,
	 * which is the right thing for all except target tables.
	 *----------
	 */
	rte->inh = inh;
	rte->inFromCl = inFromCl;
	rte->checkForRead = true;
	rte->checkForWrite = false;

	rte->checkAsUser = InvalidOid;		/* not set-uid by default, either */

	/*
	 * Add completed RTE to pstate's range table list, but not to join
	 * list nor namespace --- caller must do that if appropriate.
	 */
	if (pstate != NULL)
		pstate->p_rtable = lappend(pstate->p_rtable, rte);

	return rte;
}

/*
 * Add an entry for a subquery to the pstate's range table (p_rtable).
 *
 * This is just like addRangeTableEntry() except that it makes a subquery RTE.
 * Note that an alias clause *must* be supplied.
 */
RangeTblEntry *
addRangeTableEntryForSubquery(ParseState *pstate,
							  Query *subquery,
							  Alias *alias,
							  bool inFromCl)
{
	RangeTblEntry *rte = makeNode(RangeTblEntry);
	char	   *refname = alias->aliasname;
	Alias	   *eref;
	int			numaliases;
	int			varattno;
	List	   *tlistitem;

	rte->rtekind = RTE_SUBQUERY;
	rte->relid = InvalidOid;
	rte->subquery = subquery;
	rte->alias = alias;

	eref = copyObject(alias);
	numaliases = length(eref->colnames);

	/* fill in any unspecified alias columns */
	varattno = 0;
	foreach(tlistitem, subquery->targetList)
	{
		TargetEntry *te = (TargetEntry *) lfirst(tlistitem);

		if (te->resdom->resjunk)
			continue;
		varattno++;
		Assert(varattno == te->resdom->resno);
		if (varattno > numaliases)
		{
			char	   *attrname;

			attrname = pstrdup(te->resdom->resname);
			eref->colnames = lappend(eref->colnames, makeString(attrname));
		}
	}
	if (varattno < numaliases)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
				 errmsg("table \"%s\" has %d columns available but %d columns specified",
						refname, varattno, numaliases)));

	rte->eref = eref;

	/*----------
	 * Flags:
	 * - this RTE should be expanded to include descendant tables,
	 * - this RTE is in the FROM clause,
	 * - this RTE should be checked for read/write access rights.
	 *
	 * Subqueries are never checked for access rights.
	 *----------
	 */
	rte->inh = false;			/* never true for subqueries */
	rte->inFromCl = inFromCl;
	rte->checkForRead = false;
	rte->checkForWrite = false;

	rte->checkAsUser = InvalidOid;

	/*
	 * Add completed RTE to pstate's range table list, but not to join
	 * list nor namespace --- caller must do that if appropriate.
	 */
	if (pstate != NULL)
		pstate->p_rtable = lappend(pstate->p_rtable, rte);

	return rte;
}

/*
 * Add an entry for a function to the pstate's range table (p_rtable).
 *
 * This is just like addRangeTableEntry() except that it makes a function RTE.
 */
RangeTblEntry *
addRangeTableEntryForFunction(ParseState *pstate,
							  char *funcname,
							  Node *funcexpr,
							  RangeFunction *rangefunc,
							  bool inFromCl)
{
	RangeTblEntry *rte = makeNode(RangeTblEntry);
	Oid			funcrettype = exprType(funcexpr);
	char		functyptype;
	Alias	   *alias = rangefunc->alias;
	List	   *coldeflist = rangefunc->coldeflist;
	Alias	   *eref;
	int			numaliases;
	int			varattno;

	rte->rtekind = RTE_FUNCTION;
	rte->relid = InvalidOid;
	rte->subquery = NULL;
	rte->funcexpr = funcexpr;
	rte->coldeflist = coldeflist;
	rte->alias = alias;

	eref = alias ? (Alias *) copyObject(alias) : makeAlias(funcname, NIL);
	rte->eref = eref;

	numaliases = length(eref->colnames);

	/*
	 * Now determine if the function returns a simple or composite type,
	 * and check/add column aliases.
	 */
	if (coldeflist != NIL)
	{
		/*
		 * we *only* allow a coldeflist for functions returning a RECORD
		 * pseudo-type
		 */
		if (funcrettype != RECORDOID)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("a column definition list is only allowed for functions returning \"record\"")));
	}
	else
	{
		/*
		 * ... and a coldeflist is *required* for functions returning a
		 * RECORD pseudo-type
		 */
		if (funcrettype == RECORDOID)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("a column definition list is required for functions returning \"record\"")));
	}

	functyptype = get_typtype(funcrettype);

	if (functyptype == 'c')
	{
		/*
		 * Named composite data type, i.e. a table's row type
		 */
		Oid			funcrelid = typeidTypeRelid(funcrettype);
		Relation	rel;
		int			maxattrs;

		if (!OidIsValid(funcrelid))		/* shouldn't happen if typtype is
										 * 'c' */
			elog(ERROR, "invalid typrelid for complex type %u", funcrettype);

		/*
		 * Get the rel's relcache entry.  This access ensures that we have
		 * an up-to-date relcache entry for the rel.
		 */
		rel = relation_open(funcrelid, AccessShareLock);

		/*
		 * Since the rel is open anyway, let's check that the number of