Re: your mail

> Data files are merely the containers for data. The data in your tables may
> only use 10% of the available space, so the size of your datafiles may be
> 100 meg, but your export only 10 meg.
>
> Subtract the freespace total from the datafile total
> and this should be a good approximation of your
> database size for export purposes.
>

I believe this figure shows how many extents have been allocated to database objects which can be significantly different from what the export file will look like. I guess you could use this calculation as the upper limit for the size of the export file.

These figures are from a small database that I have:

        datafile size - freespace total:        14901248
        sum(bytes) from dba_extents:            14827520

        export file                              1335296

> you could also use 'analyze' on each table and index, and get
> a more accurate size, but this would take ( a lot ) longer.

The only way I can think of to come up with a nearly accurate size. If I run analyze compute statistics on all the tables in this database and then run this query:

        select sum(num_rows * avg_row_len) from dba_tables;

I get this figure: 1291510

This gets close to the size of the export file - grants and all that are probably the additional.

Glenn Stauffer
DBA
Swarthmore College Received on Tue Jan 16 1996 - 11:00:37 CST