From helicopter view it is more or less to create a frontend such as customer care people use for messaging/chatting type of services based on using SQL type of queries. I have no idea how this works in the blockchain as DB, since any SQL type of query can have performance impact. I only know that with 20 years experience in high end IT and telecommunications industry and solutions, I was selling a product that just did that!

The same product had also instance reporting through pre-aggregation of parameters, and we had a whole bunch of those parameters in a multi dimensional DB to allow all sort of cross views/reporting. The pre-aggregation was there to create the instant response on a report request. OLAP technology was used. The difficult part of the product was the data loader, ie the data stream from the core engines (te messaging engines, such as SMS, MMS, RCS) towards this customer care and reporting product, since it needed to support 10.000 - 50.000 tx/sec (and under race track conditions (ie no hardware failures) up to 100.000 tx/sec), and we succeeded in creating this. We had this tool separate from the core messaging engines for the obvious reason that the processing required for data loading, data aggregation and the SQL queries for customer care shall not have impact on the performance of the core messaging service.

Relating this back to blockchains (just a DB again in my helicopter view again), you want to create a copy of the blockchain and perform these type of tasks offline from the core blockchain that needs to totally focus on speed of transactions. If somehow the blockchain is sooooo superfast it can handle everything on the same blockchain, go for it, but I would say: try to find another solution since transaction speed is super super important for scale.

**NOTE: I'm not a software architect, I'm also not a software designer so my suggestions above shall be taken with precautions; However the information I provided can be taken as real and correct.**

**Note: 300 SBD bounty? Seriously? If you want a good working system being able to handle proper performance, this will cost factor of 100s more! If you just want to have the functionality but no performance at all, maybe 300 SBD or lets say factor of 10 (ie 3.000 SBD) could be sufficient**