Constant TRANSACTIONS_PER_FETCH_CEILING 

pub const TRANSACTIONS_PER_FETCH_CEILING: usize = 1024;

Ceiling on the transaction entries a fetch request or response may carry, for transaction sync and regular commit sync alike. A client requests at most its own max_transactions_per_transaction_sync_fetch or max_transactions_per_commit_sync_fetch, both validated against this at startup, and the server returns at most one entry per requested reference. Enforced while decoding each message, before its entries are materialised.