Database is growing each day

[Optira]

Hi,

I use subsonic on a raspberry and backup the folder /var/subsonic each day to a tgz-file.
Unforntunately the backup file (subsonic db) grows each day a few MB, also if I don't use Subsonic!

Samples of tgz-file size (no new file added in this time!):
03.05.2017 295 MB
.
.
.
12.05.2017 323 MB
.
.
.
20.07.2017 493 MB
21.07.2017 498 MB
22.07.2017 501 MB
23.07.2017 510 MB
24.07.2017 511 MB
25.07.2017 514 MB
26.07.2017 520 MB
27.07.2017 525 MB
28.07.2017 528 MB
29.07.2017 533 MB
30.07.2017 546 MB

Why and what can I do?

[Optira]

Hi,

nobody?

At the moment the tgz-file has 650 MB