Postgres support

[mapkyca]

Closes #76

This is very much experimental, because Postgres was giving me a headache, but I'm like a dog with a bone with this sort of thing ;)

Things not working quite yet:

• Full text search
• A better way to do on delete insertions (not supported by postgres)

[aaronpk]

What do you mean "on delete insertions"? Postgres supports triggers which let you do some pretty fancy stuff.

[mapkyca]

Probably, but I didn't really have time to figure out the various UPSERT syntaxes ;) Someone who's a bit more of a postgres wizz will be able to make this much better I'm sure! But hopefully this is a useful starting point ...

[kylewm]

ah, I see MySQL's insert ... on duplicate key update ... is not supported by Postgres. It looks like version 9.5 will introduce insert ... on conflict (_id) do update ... but it'll be quite a while until that's in most server distros.

it looks like the recommended way to make atomic upserts in older versions is with PLSQL and an exception handler, yuck. http://www.postgresql.org/docs/current/static/plpgsql-control-structures.html#PLPGSQL-UPSERT-EXAMPLE

[aaronpk]

Yeah or just do it in code to avoid the problem. As soon as you start relying on the database for fancy tricks like "on duplicate key update" you're going to be less portable.

[kylewm]

Yeah, that is what @mapkyca did