*** a/doc/src/sgml/ref/pg_basebackup.sgml
--- b/doc/src/sgml/ref/pg_basebackup.sgml
***************
*** 206,215 **** PostgreSQL documentation
        <term><option>--xlogdir=<replaceable class="parameter">xlogdir</replaceable></option></term>
        <listitem>
         <para>
!         Specifies the location for the transaction log directory. 
          <replaceable>xlogdir</replaceable> must be an absolute path.
          The transaction log directory can only be specified when
!         the backup is in plain mode.
         </para>
        </listitem>
       </varlistentry>
--- 206,216 ----
        <term><option>--xlogdir=<replaceable class="parameter">xlogdir</replaceable></option></term>
        <listitem>
         <para>
!         Specifies the location for the transaction log directory.
          <replaceable>xlogdir</replaceable> must be an absolute path.
          The transaction log directory can only be specified when
!         the backup is in plain mode. It is better not to specify
!         both data and transaction log directories are same.
         </para>
        </listitem>
       </varlistentry>
*** a/src/bin/pg_basebackup/pg_basebackup.c
--- b/src/bin/pg_basebackup/pg_basebackup.c
***************
*** 1884,1889 **** main(int argc, char **argv)
--- 1884,1891 ----
  
  	if (strcmp(xlog_dir, "") != 0)
  	{
+ 		char	   *abs_basedir;
+ 
  		if (format != 'p')
  		{
  			fprintf(stderr,
***************
*** 1904,1909 **** main(int argc, char **argv)
--- 1906,1924 ----
  					progname);
  			exit(1);
  		}
+ 
+ 		abs_basedir = make_absolute_path(basedir);
+ 		if (abs_basedir == NULL)
+ 			exit(1);
+ 
+ 		if (strcmp(abs_basedir, xlog_dir) == 0)
+ 		{
+ 			fprintf(stderr, _("%s: Provided data and transaction log "
+ 							  "directories are same\n"), progname);
+ 			exit(1);
+ 		}
+ 
+ 		free(abs_basedir);
  	}
  
  #ifndef HAVE_LIBZ