[exim] exim_tidydb doesn't make databases smaller

Hi.

Shouldn't exim_tidydb make databases physically smaller?

# ls -al /var/spool/exim/db/callout
-rw-r----- 1 exim exim 677601280 11-23 13:25 /var/spool/exim/db/callout

# exim_tidydb -t 2d /var/spool/exim/ callout > /dev/null
# ls -al /var/spool/exim/db/callout
-rw-r----- 1 exim exim 677601280 11-23 13:25 /var/spool/exim/db/callout

# exim_tidydb -t 1d /var/spool/exim/ callout > /dev/null
# ls -al /var/spool/exim/db/callout
-rw-r----- 1 exim exim 677601280 11-23 13:26 /var/spool/exim/db/callout

# exim_tidydb -t 0d /var/spool/exim/ callout > /dev/null
# ls -al /var/spool/exim/db/callout
-rw-r----- 1 exim exim 677593088 11-23 13:27 /var/spool/exim/db/callout

and no, no errors, after few calls it made db empty:
# exim_tidydb -t 0d /var/spool/exim/ callout
Tidying Exim hints database /var/spool/exim//db/callout
Tidying complete

but still

-rw-r----- 1 exim exim 677593088 11-23 13:28 /var/spool/exim/db/callout

The problem is that it grows and grows filling my /var. How to make it shrink
db?

Thanks,
--
Arkadiusz Miśkiewicz, arekm / maven.pl