concatenate question - joining 2 qvds, size question

[#1]

Hi,

I'm trying to join 2 qvds into one, below you will find the script which is supposed to do the job.

Here's what bothers me: data_1.qvd is around 30 Gb, data_2.qvd is around 2 Gb, and resulting qvd,wk_test.qvd,  is only 22 Gb.  data_1 and data_2 qvds have excatly the same structure. Number of rows in wk_test.qvd also makes sense (sum of both data_1 and data_2 rows), but why is the size of the wk_test.qvd smaller than it's expected?

Weekly_Selling:

LOAD

    field 1,

    field 2,

          ...

FROM data_1.qvd (qvd) ;

Concatenate

LOAD

    field 1,

    field 2

     ...

FROM data_2.qvd (qvd) ;

Store Weekly_Selling into wk_test.qvd;

drop table Weekly_Selling;

[#2]

To my knowledge QVD file will reduce when you combine files.  As long as  the number of rows(data) in the final QVD is correct, file size should not be a problem.

[Oleg_Troyansky]

One possibility might be that you are only loading part of the fields from the two original QVD files into the final QVD file, and that makes a difference.