migrating to 6

[calvinmetcalf]

pouchdb currently uses version 5 so if we wanted to upgrade we'd need a non-one off migration tool, I'm happy to write it, I'd just need to know how the keys are different.

[dominictarr]

the old style was like this: ($SEP$SUBLEVEL$SEP)*$KEY where the ()* pattern may repeat zero or more times... by default $SEP = \xff and $SUBLEVEL is the name of your sublevel.
level-sublevel was rewritten mainly to make encodings more flexible.
couchdb uses encoding with ordering properties similar to this: https://github.com/deanlandolt/bytewise
so you should which you can use by requireing level-sublevel/bytewise it structures keys
like this: bytewise.encode([[$sublevel*], $key]) if there is no sublevels the top level is bytewise.encode([[], $key])

[calvinmetcalf]

so something like

db.createReadStream().pipe(require('through2').obj(function (item, _, next) {
    this.push({type:'del',key:item.key});
    var split = item.key.split('\xff').slice(1);
    var key = split.pop();
    this.push({key: bytewise.encode([split, key]), value. item.value);
    next();
})).pipe(db.createWriteStream());

[dominictarr]

not quite, db.sublevel('foo').sublevel('bar').put('baz', cb)
would create a key that looked like this:
\xfffoo\xff\xffbar\xffbaz note each sublevel has $SEP$SUBLEVEL$SEP even if there is another sublevel inside it.

[calvinmetcalf]

https://github.com/calvinmetcalf/sublevel-migrate

[rvagg]

The awkwardness of the 5/6 differences and the way we have been baking a single sublevel into a db instance are making me think that for the more simple metadata storage uses it might be best to switch to an independent solution (like bytewise or something custom) and leave sublevel for the top level application concerns. The pain is mainly in the wide usage of sublevel as a middle tier solution across so many disparate level* extensions--at least that's how I've been using it, and I think that pattern might be misguided.

[dominictarr]

@rvagg can you go into more detail with some concrete examples?