comment.c

/*-------------------------------------------------------------------------
 *
 * comment.c
 *
 * PostgreSQL object comments utility code.
 *
 * Copyright (c) 1996-2013, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *	  src/backend/commands/comment.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "catalog/indexing.h"
#include "catalog/objectaddress.h"
#include "catalog/pg_description.h"
#include "catalog/pg_shdescription.h"
#include "commands/comment.h"
#include "commands/dbcommands.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/rel.h"
#include "utils/tqual.h"


/*
 * CommentObject --
 *
 * This routine is used to add the associated comment into
 * pg_description for the object specified by the given SQL command.
 */
Oid
CommentObject(CommentStmt *stmt)
{
	ObjectAddress address;
	Relation	relation;

	/*
	 * When loading a dump, we may see a COMMENT ON DATABASE for the old name
	 * of the database.  Erroring out would prevent pg_restore from completing
	 * (which is really pg_restore's fault, but for now we will work around
	 * the problem here).  Consensus is that the best fix is to treat wrong
	 * database name as a WARNING not an ERROR; hence, the following special
	 * case.  (If the length of stmt->objname is not 1, get_object_address
	 * will throw an error below; that's OK.)
	 */
	if (stmt->objtype == OBJECT_DATABASE && list_length(stmt->objname) == 1)
	{
		char	   *database = strVal(linitial(stmt->objname));

		if (!OidIsValid(get_database_oid(database, true)))
		{
			ereport(WARNING,
					(errcode(ERRCODE_UNDEFINED_DATABASE),
					 errmsg("database \"%s\" does not exist", database)));
			return InvalidOid;
		}
	}

	/*
	 * Translate the parser representation that identifies this object into an
	 * ObjectAddress.  get_object_address() will throw an error if the object
	 * does not exist, and will also acquire a lock on the target to guard