# mco_index_get_size
RT

> Return the size of the specified index .

### Prototype

        MCO_RET	mco_index_get_size(	/*IN*/ mco_trans_h t,
                        /*IN*/ uint2 index_number,
                        /*OUT*/ mco_counter_t * size );

### Arguments

t | The `mco_trans_h` transaction handle returned by `mco_trans_start()`.
index_number | A 2-byte unsigned integer representing the index for which statistics are desired. Normally, the total number of indexes is first obtained by calling `mco_index_stat_num()` then iterating.from zero to the the total number minus 1.
size | The address of a `mco_counter_t` variable to receive the index size.

### Description

> The function returns the size of the index -- the number of key values in the index structure (tree). This API is similar to the `mco_index_stat_get()`, but is faster because it doesn't perform any calculations; thus it can be used frequently. (Note that`mco_index_stat_get()` can take a substantial amount of time to return and should not be called in performance critical paths of applications.)

### Return Codes

MCO_S_OK | The index size was returned successfully.
MCO_E_INVALID_HANDLE | Database handle not opened.
MCO_E_INDEXLIMIT | Invalid index number.

### Example

        Application snippet:

        const char * dbname = "SimpleDb";

        int main(int argc, char* argv[])
        {
            mco_db_h db;
            MCO_RET rc;
            mco_device_t       dev;
            mco_db_params_t    db_params;
            mco_trans_h t;
            uint2 n_indexes;
            mco_counter_t size;
            int j;

            ...
            rc = mco_db_open_dev( dbname, simple_get_dictionary(), &dev, 1, &db_params );
            if ( MCO_S_OK != rc )
            {
                rc = mco_db_connect(  dbname, &db );
                ...
                rc = mco_trans_start(db, MCO_READ_ONLY, MCO_TRANS_FOREGROUND, &t);
                if ( MCO_S_OK == rc )
                {
                    mco_index_stat_num( t, &n_indexes );

                    for ( j=0; j < n_indexes && MCO_S_OK == rc; j++ )
                    {
                        rc = mco_index_get_size( t, j, &size );

                        if ( MCO_S_OK == rc  )
                        {
                            printf( "Index number %d size is %4d\n\t\t\t",
                                    j, size);
                        }
                    }
                    ...
                }
            }
            ...
        }

### Files

Header file:
mco.h
Source file:
mcodb.c
Library:
libmcolib.a