Increase value size limit

[d47081]

Old subject kevacoin-project#27

I think that current 3072 bytes for value is not enough and absolutely not useful in most cases.

For example, I'm interested in saving longer text in blockchain, like blog articles, web page archives, etc.

I can use third-party tools to save those data anyway, by parts, but base64 encoded where plain text or gemtext is better for ecosystem, because content explorers able to research raw data and provide decentralized search for others.

So what about increase values length to at least 10Kb, or more?

We can make some colorized indicators, according to #7 - so users will know that not all miners currently can accept their transactions. For example, green - for legacy limits, orange for partial and red when length was reached.

Note from original source:

Kevacoin is based on Bitcoin and Litecoin, with Segregated Witness (SegWit) enabled since the beginning. With SegWit, Bitcoin theoretically has a maximum block size of about 4MB. However, the non-witness part of the block has a scaling factor of 4 and the witness part a factor of 1. According to this article, 2.3MB block size would be expected with average SegWit transactions. That is about 0.6MB for the non-witness data. Kevacoin's key-value pairs are non-witness data, and will occupy part of 0.6MB if Kevacoin has the same block size setting as Bitcoin. With the maximum value size of 3KB, 0.6MB seems to be inadequate.

Kevacoin allows maximum block size of 6MB (MAX_BLOCK_WEIGHT is 6000000). The non-witness data size can be about 1MB. It is about 400KB extra space reserved for key-value pairs. Similar to Bitcoin, it is very unlikely the 6MB can be fully used due to the structure of the transaction. The expected maximal block size is about 3MB for Kevacoin.

Some related commits:

• kevacoin-project@f7a73a4