% AUTORIGHTS
% Copyright (C) 2007 Princeton University
%       
% This file is part of Ferret Toolkit.
% 
% Ferret Toolkit is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2, or (at your option)
% any later version.
% 
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
% 
% You should have received a copy of the GNU General Public License
% along with this program; if not, write to the Free Software Foundation,
% Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
\section{Index}

The system allows multiple kinds of indexing schemes to be
registered, eg: LSH, cover tree index, etc.

Cass\_table and index has one-to-many relationship:
one cass\_table can be associated with multiple indexes, while
any one index can only be associated with one cass\_table.

\begin{verbatim}
typedef _cass_idx_t {
    char *idx_name;
    cass_table_t *table;
    char *parameters;  // a copy of input paramters.
    int private_data_size;
    void *private_data;  // private data to store index-specific info.
} cass_idx_t;

char *cass_idx_estimate_paramters(cass_table_t *table);
cass_idx_t *cass_idx_create(cass_env_t *env, 
                            cass_table_t *table, char *parameters);
int cass_idx_insert(cass_idx_t *idx, cass_table_t *table, 
                    cass_vecset_t *vecset);
int cass_idx_batch_insert(cass_idx_t *idx, cass_table_t *table, 
                          cass_vecset_range_t range);  // not useful?
int cass_idx_query(cass_idx_t *idx, cass_vecset_t *qry_vecset, 
                   cass_qry_param_t *param, cass_qry_result_t *qry);
int cass_idx_batch_query(cass_idx_t *idx, uint32_t count,
                         cass_vecset_t **qry_vecset,
			 cass_qry_param_t **params,
			 cass_qry_result_t **qries);
int cass_idx_release_mem(cass_idx_t *idx);  // destroy in-mem index.
int cass_idx_checkpoint(cass_idx_t *idx, char *fname);
int cass_idx_from_disk(cass_idx_t *idx, char *fname); // idx was
                            // created by the management env.
int cass_idx_destroy(cass_env_t *env, cass_idx_t *idx);  // destroy on-disk index as well.

typdef struct _cass_idx_operations_t { 
    cass_idx_estimate_parameters,  // a set of function pointers.
    cass_idx_create,
    cass_idx_insert,
    cass_idx_query,
    cass_idx_release_mem,
    cass_idx_to_disk,
    cass_idx_from_disk,
    cass_idx_destroy,
    ...
} cass_idx_operations_t;

int cass_idx_register(char *idx_name, cass_idx_operations_t *idx_ops, 
                      enum cass_vecset_type_t vecset_type, 
		      enum cass_vec_type_t vec_type, 
		      enum cass_vecset_dist_measure_t dist_vecset,
		      enum cass_vec_distance_measure_t dist_vec,
		      ); 
    // Register idx_name, tell system what vecset_type, 
    // vec_type, dist_vecset, dist_vec it supports.
\end{verbatim}