* if mtable is not null, generates the query to filter over partitions in a table.
* if mtable is null, generates the query to filter over tables in a database
*/
private String makeQueryFilterString(MTable mtable, String filter,
Map<String, Object> params) throws MetaException {
FilterParser parser =
(filter != null && filter.length() != 0) ? getFilterParser(filter) : null;
return makeQueryFilterString(mtable, parser, params);
}