ledger_data Devnet 2025-01-28.json is a large (10.21 GB) file containing a ledger state in JSON format. As this is not an efficient way to store the ledger, it's much larger than the actual memory required by rippled to store the ledger.
The example scripts in this repo currently count "MPTokenIssuance" and "MPToken" ledger entry types.
simple_count.js simply uses substring matching to count the number of a particular type of ledger object.
count_objects.js parses the objects and checks the value of the "LedgerEntryType" field.
Usage:
npm i
node simple_count
node count_objects
node ledger_data_permissioned_domain