tablecmds.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	if (!pg_class_ownercheck(myrelid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
					   RelationGetRelationName(targetrelation));
	if (!allowSystemTableMods && IsSystemRelation(targetrelation))
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
				 errmsg("permission denied: \"%s\" is a system catalog",
						RelationGetRelationName(targetrelation))));

	/*
	 * 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)
	{
		ListCell   *child;
		List	   *children;

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

		/*
		 * 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 = lfirst_oid(child);

			if (childrelid == myrelid)
				continue;
			/* note we need not recurse again */
			renameatt(childrelid, oldattname, newattname, false, true);
		}
	}
	else
	{
		/*
		 * If we are told not to recurse, there had better not be any child
		 * tables; else the rename would put them out of step.
		 */
		if (!recursing &&
			find_inheritance_children(myrelid) != NIL)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
					 errmsg("inherited column \"%s\" must be renamed in child tables too",
							oldattname)));
	}

	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);

	atttup = SearchSysCacheCopyAttName(myrelid, oldattname);
	if (!HeapTupleIsValid(atttup))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_COLUMN),
				 errmsg("column \"%s\" does not exist",
						oldattname)));
	attform = (Form_pg_attribute) GETSTRUCT(atttup);

	attnum = attform->attnum;
	if (attnum <= 0)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("cannot rename system column \"%s\"",
						oldattname)));

	/*
	 * if the attribute is inherited, forbid the renaming, unless we are
	 * already inside a recursive rename.
	 */
	if (attform->attinhcount > 0 && !recursing)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
				 errmsg("cannot rename inherited column \"%s\"",
						oldattname)));

	/* should not already exist */
	/* this test is deliberately not attisdropped-aware */
	if (SearchSysCacheExists(ATTNAME,
							 ObjectIdGetDatum(myrelid),
							 PointerGetDatum(newattname),
							 0, 0))
		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_COLUMN),
				 errmsg("column \"%s\" of relation \"%s\" already exists",
					  newattname, RelationGetRelationName(targetrelation))));

	namestrcpy(&(attform->attname), newattname);

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

	/* keep system catalog indexes current */
	CatalogUpdateIndexes(attrelation, atttup);

	heap_freetuple(atttup);

	/*
	 * Update column names of indexes that refer to the column being renamed.
	 */
	indexoidlist = RelationGetIndexList(targetrelation);

	foreach(indexoidscan, indexoidlist)
	{
		Oid			indexoid = lfirst_oid(indexoidscan);
		HeapTuple	indextup;
		Form_pg_index indexform;
		int			i;

		/*
		 * Scan through index columns to see if there's any simple index
		 * entries for this attribute.	We ignore expressional entries.
		 */
		indextup = SearchSysCache(INDEXRELID,
								  ObjectIdGetDatum(indexoid),
								  0, 0, 0);
		if (!HeapTupleIsValid(indextup))
			elog(ERROR, "cache lookup failed for index %u", indexoid);
		indexform = (Form_pg_index) GETSTRUCT(indextup);

		for (i = 0; i < indexform->indnatts; i++)
		{
			if (attnum != indexform->indkey.values[i])
				continue;

			/*
			 * Found one, rename it.
			 */
			atttup = SearchSysCacheCopy(ATTNUM,
										ObjectIdGetDatum(indexoid),
										Int16GetDatum(i + 1),
										0, 0);
			if (!HeapTupleIsValid(atttup))
				continue;		/* should we raise an error? */

			/*
			 * Update the (copied) attribute tuple.
			 */
			namestrcpy(&(((Form_pg_attribute) GETSTRUCT(atttup))->attname),
					   newattname);

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

			/* keep system catalog indexes current */
			CatalogUpdateIndexes(attrelation, atttup);

			heap_freetuple(atttup);
		}

		ReleaseSysCache(indextup);
	}

	list_free(indexoidlist);

	heap_close(attrelation, RowExclusiveLock);

	/*
	 * Update att name in any RI triggers associated with the relation.
	 */
	if (targetrelation->rd_rel->reltriggers > 0)
	{
		/* update tgargs column reference where att is primary key */
		update_ri_trigger_args(RelationGetRelid(targetrelation),
							   oldattname, newattname,
							   false, false);
		/* update tgargs column reference where att is foreign key */
		update_ri_trigger_args(RelationGetRelid(targetrelation),
							   oldattname, newattname,
							   true, false);
	}

	relation_close(targetrelation, NoLock);		/* close rel but keep lock */
}

/*
 *		renamerel		- change the name of a relation
 *
 *		XXX - When renaming sequences, we don't bother to modify the
 *			  sequence name that is stored within the sequence itself
 *			  (this would cause problems with MVCC). In the future,
 *			  the sequence name should probably be removed from the
 *			  sequence, AFAIK there's no need for it to be there.
 */
void
renamerel(Oid myrelid, const char *newrelname)
{
	Relation	targetrelation;
	Relation	relrelation;	/* for RELATION relation */
	HeapTuple	reltup;
	Oid			namespaceId;
	char	   *oldrelname;
	char		relkind;
	bool		relhastriggers;

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

	oldrelname = pstrdup(RelationGetRelationName(targetrelation));
	namespaceId = RelationGetNamespace(targetrelation);

	if (!allowSystemTableMods && IsSystemRelation(targetrelation))
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
				 errmsg("permission denied: \"%s\" is a system catalog",
						RelationGetRelationName(targetrelation))));

	relkind = targetrelation->rd_rel->relkind;
	relhastriggers = (targetrelation->rd_rel->reltriggers > 0);

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

	reltup = SearchSysCacheCopy(RELOID,
								PointerGetDatum(myrelid),
								0, 0, 0);
	if (!HeapTupleIsValid(reltup))		/* shouldn't happen */
		elog(ERROR, "cache lookup failed for relation %u", myrelid);

	if (get_relname_relid(newrelname, namespaceId) != InvalidOid)
		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_TABLE),
				 errmsg("relation \"%s\" already exists",
						newrelname)));

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

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

	/* keep the system catalog indexes current */
	CatalogUpdateIndexes(relrelation, reltup);

	heap_freetuple(reltup);
	heap_close(relrelation, RowExclusiveLock);

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

	/*
	 * Update rel name in any RI triggers associated with the relation.
	 */
	if (relhastriggers)
	{
		/* update tgargs where relname is primary key */
		update_ri_trigger_args(myrelid,
							   oldrelname,
							   newrelname,
							   false, true);
		/* update tgargs where relname is foreign key */
		update_ri_trigger_args(myrelid,
							   oldrelname,
							   newrelname,
							   true, true);
	}

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

/*
 * Scan pg_trigger for RI triggers that are on the specified relation
 * (if fk_scan is false) or have it as the tgconstrrel (if fk_scan
 * is true).  Update RI trigger args fields matching oldname to contain
 * newname instead.  If update_relname is true, examine the relname
 * fields; otherwise examine the attname fields.
 */
static void
update_ri_trigger_args(Oid relid,
					   const char *oldname,
					   const char *newname,
					   bool fk_scan,
					   bool update_relname)
{
	Relation	tgrel;
	ScanKeyData skey[1];
	SysScanDesc trigscan;
	HeapTuple	tuple;
	Datum		values[Natts_pg_trigger];
	char		nulls[Natts_pg_trigger];
	char		replaces[Natts_pg_trigger];

	tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
	if (fk_scan)
	{
		ScanKeyInit(&skey[0],
					Anum_pg_trigger_tgconstrrelid,
					BTEqualStrategyNumber, F_OIDEQ,
					ObjectIdGetDatum(relid));
		trigscan = systable_beginscan(tgrel, TriggerConstrRelidIndexId,
									  true, SnapshotNow,
									  1, skey);
	}
	else
	{
		ScanKeyInit(&skey[0],
					Anum_pg_trigger_tgrelid,
					BTEqualStrategyNumber, F_OIDEQ,
					ObjectIdGetDatum(relid));
		trigscan = systable_beginscan(tgrel, TriggerRelidNameIndexId,
									  true, SnapshotNow,
									  1, skey);
	}

	while ((tuple = systable_getnext(trigscan)) != NULL)
	{
		Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple);
		bytea	   *val;
		bytea	   *newtgargs;
		bool		isnull;
		int			tg_type;
		bool		examine_pk;
		bool		changed;
		int			tgnargs;
		int			i;
		int			newlen;
		const char *arga[RI_MAX_ARGUMENTS];
		const char *argp;

		tg_type = RI_FKey_trigger_type(pg_trigger->tgfoid);
		if (tg_type == RI_TRIGGER_NONE)
		{
			/* Not an RI trigger, forget it */
			continue;
		}

		/*
		 * It is an RI trigger, so parse the tgargs bytea.
		 *
		 * NB: we assume the field will never be compressed or moved out of
		 * line; so does trigger.c ...
		 */
		tgnargs = pg_trigger->tgnargs;
		val = (bytea *)
			DatumGetPointer(fastgetattr(tuple,
										Anum_pg_trigger_tgargs,
										tgrel->rd_att, &isnull));
		if (isnull || tgnargs < RI_FIRST_ATTNAME_ARGNO ||
			tgnargs > RI_MAX_ARGUMENTS)
		{
			/* This probably shouldn't happen, but ignore busted triggers */
			continue;
		}
		argp = (const char *) VARDATA(val);
		for (i = 0; i < tgnargs; i++)
		{
			arga[i] = argp;
			argp += strlen(argp) + 1;
		}

		/*
		 * Figure out which item(s) to look at.  If the trigger is primary-key
		 * type and attached to my rel, I should look at the PK fields; if it
		 * is foreign-key type and attached to my rel, I should look at the FK
		 * fields.	But the opposite rule holds when examining triggers found
		 * by tgconstrrel search.
		 */
		examine_pk = (tg_type == RI_TRIGGER_PK) == (!fk_scan);

		changed = false;
		if (update_relname)
		{
			/* Change the relname if needed */
			i = examine_pk ? RI_PK_RELNAME_ARGNO : RI_FK_RELNAME_ARGNO;
			if (strcmp(arga[i], oldname) == 0)
			{
				arga[i] = newname;
				changed = true;
			}
		}
		else
		{
			/* Change attname(s) if needed */
			i = examine_pk ? RI_FIRST_ATTNAME_ARGNO + RI_KEYPAIR_PK_IDX :
				RI_FIRST_ATTNAME_ARGNO + RI_KEYPAIR_FK_IDX;
			for (; i < tgnargs; i += 2)
			{
				if (strcmp(arga[i], oldname) == 0)
				{
					arga[i] = newname;
					changed = true;
				}
			}
		}

		if (!changed)
		{
			/* Don't need to update this tuple */
			continue;
		}

		/*
		 * Construct modified tgargs bytea.
		 */
		newlen = VARHDRSZ;
		for (i = 0; i < tgnargs; i++)
			newlen += strlen(arga[i]) + 1;
		newtgargs = (bytea *) palloc(newlen);
		VARATT_SIZEP(newtgargs) = newlen;
		newlen = VARHDRSZ;
		for (i = 0; i < tgnargs; i++)
		{
			strcpy(((char *) newtgargs) + newlen, arga[i]);
			newlen += strlen(arga[i]) + 1;
		}

		/*
		 * Build modified tuple.
		 */
		for (i = 0; i < Natts_pg_trigger; i++)
		{
			values[i] = (Datum) 0;
			replaces[i] = ' ';
			nulls[i] = ' ';