rewritedefine.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 588 行 · 第 1/2 页

/*-------------------------------------------------------------------------
 *
 * rewriteDefine.c
 *	  routines for defining a rewrite rule
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.90 2003/09/29 00:05:25 petere Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/pg_rewrite.h"
#include "commands/view.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "parser/parse_relation.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteManip.h"
#include "rewrite/rewriteSupport.h"
#include "storage/smgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"


static void setRuleCheckAsUser(Query *qry, AclId userid);
static bool setRuleCheckAsUser_walker(Node *node, Oid *context);


/*
 * InsertRule -
 *	  takes the arguments and inserts them as a row into the system
 *	  relation "pg_rewrite"
 */
static Oid
InsertRule(char *rulname,
		   int evtype,
		   Oid eventrel_oid,
		   AttrNumber evslot_index,
		   bool evinstead,
		   Node *event_qual,
		   List *action,
		   bool replace)
{
	char	   *evqual = nodeToString(event_qual);
	char	   *actiontree = nodeToString((Node *) action);
	int			i;
	Datum		values[Natts_pg_rewrite];
	char		nulls[Natts_pg_rewrite];
	char		replaces[Natts_pg_rewrite];
	NameData	rname;
	Relation	pg_rewrite_desc;
	HeapTuple	tup,
				oldtup;
	Oid			rewriteObjectId;
	ObjectAddress myself,
				referenced;
	bool		is_update = false;

	/*
	 * Set up *nulls and *values arrays
	 */
	MemSet(nulls, ' ', sizeof(nulls));

	i = 0;
	namestrcpy(&rname, rulname);
	values[i++] = NameGetDatum(&rname); /* rulename */
	values[i++] = ObjectIdGetDatum(eventrel_oid);		/* ev_class */
	values[i++] = Int16GetDatum(evslot_index);	/* ev_attr */
	values[i++] = CharGetDatum(evtype + '0');	/* ev_type */
	values[i++] = BoolGetDatum(evinstead);		/* is_instead */
	values[i++] = DirectFunctionCall1(textin, CStringGetDatum(evqual)); /* ev_qual */
	values[i++] = DirectFunctionCall1(textin, CStringGetDatum(actiontree));		/* ev_action */

	/*
	 * Ready to store new pg_rewrite tuple
	 */
	pg_rewrite_desc = heap_openr(RewriteRelationName, RowExclusiveLock);

	/*
	 * Check to see if we are replacing an existing tuple
	 */
	oldtup = SearchSysCache(RULERELNAME,
							ObjectIdGetDatum(eventrel_oid),
							PointerGetDatum(rulname),
							0, 0);

	if (HeapTupleIsValid(oldtup))
	{
		if (!replace)
			ereport(ERROR,
					(errcode(ERRCODE_DUPLICATE_OBJECT),
				 errmsg("rule \"%s\" for relation \"%s\" already exists",
						rulname, get_rel_name(eventrel_oid))));

		/*
		 * When replacing, we don't need to replace every attribute
		 */
		MemSet(replaces, ' ', sizeof(replaces));
		replaces[Anum_pg_rewrite_ev_attr - 1] = 'r';
		replaces[Anum_pg_rewrite_ev_type - 1] = 'r';
		replaces[Anum_pg_rewrite_is_instead - 1] = 'r';
		replaces[Anum_pg_rewrite_ev_qual - 1] = 'r';
		replaces[Anum_pg_rewrite_ev_action - 1] = 'r';

		tup = heap_modifytuple(oldtup, pg_rewrite_desc,
							   values, nulls, replaces);

		simple_heap_update(pg_rewrite_desc, &tup->t_self, tup);

		ReleaseSysCache(oldtup);

		rewriteObjectId = HeapTupleGetOid(tup);
		is_update = true;
	}
	else
	{
		tup = heap_formtuple(pg_rewrite_desc->rd_att, values, nulls);

		rewriteObjectId = simple_heap_insert(pg_rewrite_desc, tup);
	}

	/* Need to update indexes in either case */
	CatalogUpdateIndexes(pg_rewrite_desc, tup);

	heap_freetuple(tup);

	/* If replacing, get rid of old dependencies and make new ones */
	if (is_update)
		deleteDependencyRecordsFor(RelationGetRelid(pg_rewrite_desc),
								   rewriteObjectId);

	/*
	 * Install dependency on rule's relation to ensure it will go away on
	 * relation deletion.  If the rule is ON SELECT, make the dependency
	 * implicit --- this prevents deleting a view's SELECT rule.  Other
	 * kinds of rules can be AUTO.
	 */
	myself.classId = RelationGetRelid(pg_rewrite_desc);
	myself.objectId = rewriteObjectId;
	myself.objectSubId = 0;

	referenced.classId = RelOid_pg_class;
	referenced.objectId = eventrel_oid;
	referenced.objectSubId = 0;

	recordDependencyOn(&myself, &referenced,
		 (evtype == CMD_SELECT) ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO);

	/*
	 * Also install dependencies on objects referenced in action and qual.
	 */
	recordDependencyOnExpr(&myself, (Node *) action, NIL,
						   DEPENDENCY_NORMAL);

	if (event_qual != NULL)
	{
		/* Find query containing OLD/NEW rtable entries */
		Query	   *qry = (Query *) lfirst(action);

		qry = getInsertSelectQuery(qry, NULL);
		recordDependencyOnExpr(&myself, event_qual, qry->rtable,
							   DEPENDENCY_NORMAL);
	}

	heap_close(pg_rewrite_desc, RowExclusiveLock);

	return rewriteObjectId;
}

void
DefineQueryRewrite(RuleStmt *stmt)
{
	RangeVar   *event_obj = stmt->relation;
	Node	   *event_qual = stmt->whereClause;
	CmdType		event_type = stmt->event;
	bool		is_instead = stmt->instead;
	bool		replace = stmt->replace;
	List	   *action = stmt->actions;
	Relation	event_relation;
	Oid			ev_relid;
	Oid			ruleId;
	int			event_attno;
	Oid			event_attype;
	List	   *l;
	Query	   *query;
	AclResult	aclresult;
	bool		RelisBecomingView = false;

	/*
	 * If we are installing an ON SELECT rule, we had better grab
	 * AccessExclusiveLock to ensure no SELECTs are currently running on
	 * the event relation.	For other types of rules, it might be
	 * sufficient to grab ShareLock to lock out insert/update/delete
	 * actions.  But for now, let's just grab AccessExclusiveLock all the
	 * time.
	 */
	event_relation = heap_openrv(event_obj, AccessExclusiveLock);
	ev_relid = RelationGetRelid(event_relation);

	/*
	 * Check user has permission to apply rules to this relation.
	 */
	aclresult = pg_class_aclcheck(ev_relid, GetUserId(), ACL_RULE);
	if (aclresult != ACLCHECK_OK)
		aclcheck_error(aclresult, ACL_KIND_CLASS,
					   RelationGetRelationName(event_relation));

	/*
	 * No rule actions that modify OLD or NEW
	 */
	foreach(l, action)
	{
		query = (Query *) lfirst(l);
		if (query->resultRelation == 0)
			continue;
		/* Don't be fooled by INSERT/SELECT */
		if (query != getInsertSelectQuery(query, NULL))
			continue;
		if (query->resultRelation == PRS2_OLD_VARNO)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("rule actions on OLD are not implemented"),
					 errhint("Use views or triggers instead.")));
		if (query->resultRelation == PRS2_NEW_VARNO)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("rule actions on NEW are not implemented"),
					 errhint("Use triggers instead.")));
	}

	/*
	 * Rules ON SELECT are restricted to view definitions
	 */
	if (event_type == CMD_SELECT)
	{
		List	   *tllist;
		int			i;

		/*
		 * So there cannot be INSTEAD NOTHING, ...
		 */
		if (length(action) == 0)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
			errmsg("INSTEAD NOTHING rules on SELECT are not implemented"),
					 errhint("Use views instead.")));

		/*
		 * ... there cannot be multiple actions, ...
		 */
		if (length(action) > 1)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("multiple actions for rules on SELECT are not implemented")));

		/*
		 * ... the one action must be a SELECT, ...
		 */
		query = (Query *) lfirst(action);
		if (!is_instead || query->commandType != CMD_SELECT)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("rules on SELECT must have action INSTEAD SELECT")));

		/*
		 * ... there can be no rule qual, ...
		 */
		if (event_qual != NULL)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("event qualifications are not implemented for rules on SELECT")));

		/*
		 * ... the targetlist of the SELECT action must exactly match the
		 * event relation, ...
		 */
		i = 0;
		foreach(tllist, query->targetList)
		{
			TargetEntry *tle = (TargetEntry *) lfirst(tllist);
			Resdom	   *resdom = tle->resdom;
			Form_pg_attribute attr;
			char	   *attname;