/*-------------------------------------------------------------------------
 *
 * rename.c
 *	  renameatt() and renamerel() reside here.
 *
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/commands/Attic/rename.c,v 1.56 2001/03/22 03:59:23 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <errno.h>

#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/pg_type.h"
#include "catalog/heap.h"
#include "catalog/indexing.h"
#include "catalog/catalog.h"
#include "commands/rename.h"
#include "miscadmin.h"
#include "storage/smgr.h"
#include "optimizer/prep.h"
#include "utils/acl.h"
#include "utils/relcache.h"
#include "utils/syscache.h"
#include "utils/temprel.h"


/*
 *		renameatt		- changes the name of a attribute in a relation
 *
 *		Attname attribute is changed in attribute catalog.
 *		No record of the previous attname is kept (correct?).
 *
 *		get proper relrelation from relation catalog (if not arg)
 *		scan attribute catalog
 *				for name conflict (within rel)
 *				for original attribute (if not arg)
 *		modify attname in attribute tuple
 *		insert modified attribute in attribute catalog
 *		delete original attribute from attribute catalog
 *
 *		XXX Renaming an indexed attribute must (eventually) also change
 *				the attribute name in the associated indexes.
 */
void
renameatt(char *relname,
		  char *oldattname,
		  char *newattname,
		  int recurse)
{
	Relation	targetrelation;
	Relation	attrelation;
	HeapTuple	reltup,
				atttup;
	Oid			relid;

	/*
	 * permissions checking.  this would normally be done in utility.c,
	 * but this particular routine is recursive.
	 *
	 * normally, only the owner of a class can change its schema.
	 */
	if (!allowSystemTableMods && IsSystemRelationName(relname))
		elog(ERROR, "renameatt: class \"%s\" is a system catalog",
			 relname);
	if (!IsBootstrapProcessingMode() &&
		!pg_ownercheck(GetUserId(), relname, RELNAME))
		elog(ERROR, "renameatt: you do not own class \"%s\"",
			 relname);

	/*
	 * Grab an exclusive lock on the target table, which we will NOT
	 * release until end of transaction.
	 */
	targetrelation = heap_openr(relname, AccessExclusiveLock);
	relid = RelationGetRelid(targetrelation);
	heap_close(targetrelation, NoLock); /* close rel but keep lock! */

	/*
	 * if the 'recurse' flag is set then we are supposed to rename this
	 * attribute in all classes that inherit from 'relname' (as well as in
	 * 'relname').
	 *
	 * any permissions or problems with duplicate attributes will cause the
	 * whole transaction to abort, which is what we want -- all or
	 * nothing.
	 */
	if (recurse)
	{
		List	   *child,
				   *children;

		/* this routine is actually in the planner */
		children = find_all_inheritors(relid);

		/*
		 * find_all_inheritors does the recursive search of the
		 * inheritance hierarchy, so all we have to do is process all of
		 * the relids in the list that it returns.
		 */
		foreach(child, children)
		{
			Oid			childrelid = lfirsti(child);
			char		childname[NAMEDATALEN];

			if (childrelid == relid)
				continue;
			reltup = SearchSysCache(RELOID,
									ObjectIdGetDatum(childrelid),
									0, 0, 0);
			if (!HeapTupleIsValid(reltup))
			{
				elog(ERROR, "renameatt: can't find catalog entry for inheriting class with oid %u",
					 childrelid);
			}
			/* make copy of cache value, could disappear in call */
			StrNCpy(childname,
					NameStr(((Form_pg_class) GETSTRUCT(reltup))->relname),
					NAMEDATALEN);
			ReleaseSysCache(reltup);
			/* note we need not recurse again! */
			renameatt(childname, oldattname, newattname, 0);
		}
	}

	attrelation = heap_openr(AttributeRelationName, RowExclusiveLock);

	atttup = SearchSysCacheCopy(ATTNAME,
								ObjectIdGetDatum(relid),
								PointerGetDatum(oldattname),
								0, 0);
	if (!HeapTupleIsValid(atttup))
		elog(ERROR, "renameatt: attribute \"%s\" does not exist", oldattname);

	if (((Form_pg_attribute) GETSTRUCT(atttup))->attnum < 0)
		elog(ERROR, "renameatt: system attribute \"%s\" not renamed", oldattname);

	/* should not already exist */
	if (SearchSysCacheExists(ATTNAME,
							 ObjectIdGetDatum(relid),
							 PointerGetDatum(newattname),
							 0, 0))
		elog(ERROR, "renameatt: attribute \"%s\" exists", newattname);

	StrNCpy(NameStr(((Form_pg_attribute) GETSTRUCT(atttup))->attname),
			newattname, NAMEDATALEN);

	simple_heap_update(attrelation, &atttup->t_self, atttup);

	/* keep system catalog indices current */
	{
		Relation	irelations[Num_pg_attr_indices];

		CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, irelations);
		CatalogIndexInsert(irelations, Num_pg_attr_indices, attrelation, atttup);
		CatalogCloseIndices(Num_pg_attr_indices, irelations);
	}

	heap_freetuple(atttup);
	heap_close(attrelation, RowExclusiveLock);
}

/*
 *		renamerel		- change the name of a relation
 */
void
renamerel(const char *oldrelname, const char *newrelname)
{
	Relation	targetrelation;
	Relation	relrelation;	/* for RELATION relation */
	HeapTuple	reltup;
	Oid			reloid;
	char		relkind;
	Relation	irelations[Num_pg_class_indices];

	if (!allowSystemTableMods && IsSystemRelationName(oldrelname))
		elog(ERROR, "renamerel: system relation \"%s\" may not be renamed",
			 oldrelname);

	if (!allowSystemTableMods && IsSystemRelationName(newrelname))
		elog(ERROR, "renamerel: Illegal class name: \"%s\" -- pg_ is reserved for system catalogs",
			 newrelname);

	/*
	 * Check for renaming a temp table, which only requires altering the
	 * temp-table mapping, not the underlying table.
	 */
	if (rename_temp_relation(oldrelname, newrelname))
		return;					/* all done... */

	/*
	 * Instead of using heap_openr(), do it the hard way, so that we can
	 * rename indexes as well as regular relations.
	 */
	targetrelation = RelationNameGetRelation(oldrelname);

	if (!RelationIsValid(targetrelation))
		elog(ERROR, "Relation \"%s\" does not exist", oldrelname);

	/*
	 * Grab an exclusive lock on the target table, which we will NOT
	 * release until end of transaction.
	 */
	LockRelation(targetrelation, AccessExclusiveLock);

	reloid = RelationGetRelid(targetrelation);
	relkind = targetrelation->rd_rel->relkind;

	/*
	 * Close rel, but keep exclusive lock!
	 */
	heap_close(targetrelation, NoLock);

	/*
	 * Flush the relcache entry (easier than trying to change it at
	 * exactly the right instant).	It'll get rebuilt on next access to
	 * relation.
	 *
	 * XXX What if relation is myxactonly?
	 *
	 * XXX this is probably not necessary anymore?
	 */
	RelationIdInvalidateRelationCacheByRelationId(reloid);

	/*
	 * Find relation's pg_class tuple, and make sure newrelname isn't in
	 * use.
	 */
	relrelation = heap_openr(RelationRelationName, RowExclusiveLock);

	reltup = SearchSysCacheCopy(RELNAME,
								PointerGetDatum(oldrelname),
								0, 0, 0);
	if (!HeapTupleIsValid(reltup))
		elog(ERROR, "renamerel: relation \"%s\" does not exist", oldrelname);

	if (RelnameFindRelid(newrelname) != InvalidOid)
		elog(ERROR, "renamerel: relation \"%s\" exists", newrelname);

	/*
	 * Update pg_class tuple with new relname.	(Scribbling on reltup is
	 * OK because it's a copy...)
	 */
	StrNCpy(NameStr(((Form_pg_class) GETSTRUCT(reltup))->relname),
			newrelname, NAMEDATALEN);

	simple_heap_update(relrelation, &reltup->t_self, reltup);

	/* keep the system catalog indices current */
	CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, irelations);
	CatalogIndexInsert(irelations, Num_pg_class_indices, relrelation, reltup);
	CatalogCloseIndices(Num_pg_class_indices, irelations);

	heap_close(relrelation, NoLock);

	/*
	 * Also rename the associated type, if any.
	 */
	if (relkind != RELKIND_INDEX)
		TypeRename(oldrelname, newrelname);
}
