pouchdb or alternative where I can control how much data stored locally?

Question

In the design stage for an app that collects large amounts of data...

Ideally, I want it to be an offline-first app and was looking to Pouchdb/Counchdb - However, the data needs to be kept for years for legal reasons, and my concern is that this is going to consume too much local storage over time.

My thoughts were:

1. handle sync between pouchdb and couchdb myself, allowing me to purge inactive documents from the local store without impacting the couchdb. This feels messy and probably a lot of work
2. Build a local store using dexie.js and completely write the sync function. It also looks hard work, but may be less as I'm not trying to mess with a sync function
3. Search harder:)

Conceptually, I guess I'm looking for a 'DB cache' - holding active json document versions and removing documents that have not been touched for X period. It might be that 'offline' mode is handled separate to the DB cache..

Answer 1

Not sure yet if this is the correct answer..

1. setup a filter on couchdb to screen out old documents (lets say we have a 'date_modified' field in the doc and we filter out any docs with date_modified older than one month)
2. have a local routine on the client that deletes documents from the local pouchdb that are older than one month ( actually using the remove() method against the local pouchdb, not updating it with _deleted:true) - from https://pouchdb.com/2015/04/05/filtered-replication.html it appears removed documents don't sync.
3. docs updated on the Pouchdb will replicate normally

there might be a race condition here for replication, we'll see