Balance Views Grouped By Keyset

[lollerfirst]

Issues:

• Mint: Limits and balance views per keyset #650
• Add MINT_MAX_BALANCE_ISSUED setting #646

Balance views new SQL:

CREATE VIEW {db.table_with_schema('balance_issued')} AS
SELECT id AS keyset, COALESCE(s, 0) AS balance FROM (
    SELECT id, SUM(amount) AS s
    FROM {db.table_with_schema('promises')}
    WHERE amount > 0
    GROUP BY id
);

CREATE VIEW {db.table_with_schema('balance_redeemed')} AS
SELECT id AS keyset, COALESCE(s, 0) AS balance FROM (
    SELECT id, SUM(amount) AS s
    FROM {db.table_with_schema('proofs_used')}
    WHERE amount > 0
    GROUP BY id
);

CREATE VIEW {db.table_with_schema('balance')} AS
SELECT keyset, s_issued - s_used AS balance FROM (
    SELECT bi.keyset AS keyset,
        bi.balance AS s_issued,
        COALESCE(bu.balance, 0) AS s_used
    FROM {db.table_with_schema('balance_issued')} bi
    LEFT OUTER JOIN {db.table_with_schema('balance_redeemed')} bu
    ON bi.keyset = bu.keyset
);

New migration m022_keyset_specific_balance_views takes care of deleting the previous views and replacing them with these.

Some minor relative changes to get_balance() functions.

[lollerfirst]

# Max mint balance in satoshis
# MINT_MAX_BALANCE=1000000
# Max peg-in amount in satoshis
# MINT_MAX_PEG_IN=100000
# Max peg-out amount in satoshis
# MINT_MAX_PEG_OUT=100000
# Use to allow only peg-out to LN
# MINT_PEG_OUT_ONLY=FALSE

I think the scope of this PR should be limited to fixing the balance views. We can do the limits settings for different units in a follow-up. Sounds good?

[callebtc]

I think the scope of this PR should be limited to fixing the balance views.

agreed!

[callebtc]

Please rebase to main

[lollerfirst]

re-based.