Increase number of decimal places in sdk.Decimal

[ValarDragon]

Decimals are needed in fee distribution / inflation, to ensure that you still get rewards when you only have like 1 piece of a validators stake. Currently a validator's tm power could be as large as 2**63 - 1. Thus we require decimals to account for you getting 1 / (2**63 - 1) of a token of rewards. log_10(2**63 - 1) = 18.9, so we need at least 19 decimal digits, not the 10 we have now.

We need to lower this max tm power (tendermint/tendermint#2985). Per latest comment, max amount of tm power per validator would be at most 2**63 - 1 / num_validators, taking num_validators as 100, that'd require 17 decimal digits at least.

[cwgoes]

Isn't the effective bound on Tendermint power dependent on total supply, not purely the TM maximums?

[ValarDragon]

Yes, the total supply part is independent of the decimal places of precision required though. The total supply is tracked via #2513

[cwgoes]

I will add some tests for this in #3099.

[jackzampolin]

Is this still an issue?

[ValarDragon]

Yes.