You have a Russian tool made for extraction of the .db files, GUIFORUNPACKERv.1.1. You have to look for it elsewhere, because GSC's forum is still down.
Working 100% and is fast.
Found a download link: http://stalkerin.gameru.net/downloads/stutils/packers/GUIFORUNPACKERv.1.1.rar
Unpacking Order:
levels:
1. levels.db0 (optional)
2. levels.db1 (optional)
3. levels.db2 (optional)
localization:
4. xenglish.db (optional)
resources:
5. configs.db
6. resources.db0
7. resources.db1
8. resources.db2
patches:
9. Start with the oldest patch, lowest number oldest patch.