Speeding up RPC-only indexing with bisection hooks

[PaulRBerg]

Problem

RPC-only indexing is painfully slow. Some of our indexers have been running for days without catching up to the chain tip.
The main culprits: small max block ranges, flaky RPC endpoints, and the usual RPC headaches.

Solution

Let’s allow users to plug in custom “bisection” hooks (functions/oracles—call them what you want). These would let the Envio indexer run a binary search to quickly rule out block ranges that don’t contain relevant transactions.

A couple of examples:

• State root check: Did the smart contract’s state root change at all? If yes → there was at least one tx in this range.
• ERC-20 balance check: Did the token balance of the contract change?

Users could combine hooks too (e.g. to filter out false positives where balances stay the same even if txs occurred).

The big win: indexing gets much faster since we skip huge swaths of “empty” blocks.