ethereum/go-ethereum

Feature Request: A query that returns the most recent event for a given filter.

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#20593 opened on Jan 25, 2020

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help wantedtype:feature

Description

Thanks to the developers for this great software!

This is a "would be nice to have" feature request to add a flag to the JSON-RPC/GraphQL query input have Geth search for the events in reverse chronological order and only return the most recent log (or the batch from that block).

Unless I'm mistaken, at the moment it is only possible to construct queries that return all of the events for a given filter.

If you have a case where you only want the most recent event, but you don't know when it occurred, you still need to get back all of the events and filter (potentially not ideal on a client machine).

See also:

https://ethereum.stackexchange.com/questions/41976/how-to-get-only-latest-log-from-my-event https://ethereum.stackexchange.com/questions/8699/how-to-get-only-latest-logged-event-via-web3-api

Thanks,

Lee

Contributor guide

Tech stack
gographql
Domain
blockchainapi
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Go programmingEthereum event logsGeth RPC layer
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Explore the existing event filtering code in the go ethereum codebase, specifically the eth/filters package. Understand how filters are currently constructed and applied. Investigate how the GraphQL endpoint handles event queries (likely in internal/graphql). Propose a way to add a 'latestOnly' flag that modifies the query to return only the most recent log. Check if there are any existing PRs or discussions on this feature.