Noob Q: Is the PG database its own source code backup?

I find myself hacking away in pgAdmin most of the time now, after early
on keeping PG source code in text files I could preserve in SVN. At this
point I cannot point to anything other than the pg db itself that has a
full description.

Is this normal? Or do folks assiduously maintain an external set of
scripts and always work from those, resisting the temptation to just
hack at the db with pgAdmin or psql? Or_______?

kt