Some time ago I talked about a certain idea of mine called Hierarchical Self-Purging Blockchains which you can read following the link. It's just a concept and there is no whitepaper or anything. But I just found another use case for my idea. Take a look at this table from @steemchille who is the creator of https://steemworld.org

From Block	To Block	File Size (uncompressed)
1	100,000	6 MB
10,000,000	10,100,000	104 MB
20,000,000	20,100,000	1.6 GB

More and more Transactions are happening on pretty much every single popular blockchain and other non-blockchains like IOTA and NANO. I'll use another quote from his recent post below:

What most people might think:

Just call blockchain -> getMentions( permlink ) and show the results on SteemWorld ;)

Reality:

Nope! One needs to go through all the > 21.8 million blocks. Each block can contain many operations. Did you ever try to collect a specific information from a 95 GB file? It's fun, but it always takes many hours!

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Keep in mind:

There is one new block ~ every 3 seconds and the blocks are growing in size as more and more people are using Steem on a daily basis. I think the huge increase in the recent months is really a good sign!

Not All Blockchains are like STEEM. Let's look at currency specialized projects

STEEM is a social media platform. EOS is a smart contract platform. These things won't benifit much from a Hierarchical Blockchain. You need to have the kind of data/information that can be discarded after achieving a certain task. In a blockchain based game, one could discard the record of the moves of individual game sessions and simply keep the final data. In the case of a "Currency" what ultimately matters is that we maintain an accurate and immutable record of who owns what.

Private Transactions on Mobile devices

Privacy coins, whether employing mixing like Dash or encryption like Zcash, Monero, and many others, require a full node in order to broadcast privately. Because light wallets (also known as thin clients) have to communicate with a full node in order to send transactions. In order to communicate with the node, however, certain data must be transmitted to complete the transaction, and in order for the node to read it that data must not be private. Any coin presently using enhanced privacy functions on mobile devices, web wallets, etc., therefore has to compromise by trusting the node with its data. While this setup is an improvement over simply not using any anonymization features, many privacy coins eschew this imperfect approach because of the potential for creating honeypots of privacy-seeking users with a central point of de-anonymization.
Source

All blockchains are growing in a rapid pace and mobile devices are certainly not going to keep up. Smartphone users from developing nations with cheap devices will be barely willing to store 1 GB file on their phone. Even an iPhone user may not be willing to store more than 10 GB even for the sake of privacy. Ease of use is really important. If if you can trust a node owner, you can't trust that a government won't be able to coerce those node owners. If full nodes can be run on mobiles, we can keep the whole privacy business trustless and without central point of failure.

Light Wallet+Full Wallet Combo

The advantage of a Hierarchical Blockchain is that a statement like the subtitle above won't sound ridiculous. A mobile wallet could use a Light Wallet like it's done today and this Light Wallet would deal with a Full node of a lower level of the blockchain which has a tiny block time of few seconds or even under 1 second. The Full Wallet could be from a higher level which could even have a multi-hour block time. This should keep the size of a full node minimum and make it grow at a small pace so that the mobile wallets can have that privacy in a totally trustless manner.

This is just an idea and I haven'made any software based on that. I'm not even skilled enough to develop for a blockchain project. But I see an idea that could vastly reduce the growth of a blockchain file size while allowing massive on chain scaling,privacy as a side effect of self-purging nature while also giving the ability to use privacy features on mobile devices. So at least I can at least say that my time spent thinking wasn't wasted.

Thank for reading.Until next time,
Happy steeming!

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