MaxChildKeyTakeSet

Event Re-added v195 → v219, v233 → v247, v252 → v265, v273 → v277, v290 → v315, v320 → current #45

Emitted when maximum child key take rate is changed.

Useful for: validatorsdelegatorssubnet ownersanalytics

The Big Picture

When parent hotkeys share rewards with child keys, the child can set their own take (commission) on their allocated portion. MaxChildKeyTake caps this, preventing child keys from taking excessive commissions. This protects the economic structure of validator organizations and ensures allocated rewards flow through reasonably to stakers.

Why This Matters

If you're delegating to a parent hotkey with children, you need to understand the full take structure. The parent takes their cut, then allocated funds go to children, who take their cut. MaxChildKeyTake limits how much children can extract, protecting your effective return.

Example Scenario

Governance sets MaxChildKeyTake to 20%. MaxChildKeyTakeSet fires. Child keys trying to set 30% take will fail - they're capped at 20%. This ensures that even in complex validator hierarchies, rewards flow through to end stakers reasonably.

Common Questions

How does this interact with delegate take?: They're separate. Delegate take is what the main validator charges. Child key take is what children charge on their allocation. Both have their own min/max limits.
Why cap child key take separately from delegate take?: Parent-child relationships have different economics. Children are often partners or referrers, not independent validators. Different caps allow different incentive structures.
What if a child key is currently above the new max?: Similar to delegates: they're grandfathered but can't increase. If they ever lower their take, they can't raise it back above the new max.

Use Cases

Track maximum commission child keys can charge
Understand validator organization commission limits
Monitor network policies for parent-child relationships
Build validator structure analysis tools

How to Use This Event

→ Monitor for changes affecting validator organizations
→ Track governance policies for complex validator structures
→ Build tools analyzing child key economics

From Chain Metadata

maximum childkey take set

Triggers

Emitted by

sudo_set_max_childkey_take

Preconditions

Caller has admin/sudo privileges

Effects

Storage Modified

MaxChildkeyTake

Postconditions

MaxChildKeyTake updated

Side Effects

Child keys cannot set take above this value

Event Data

#	Name	Type	Description
0	arg0	u16	Event field #0 (u16)

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Subscribe to MaxChildKeyTakeSet events
api.query.system.events((events) => {
  events
    .filter(({ event }) =>
      event.section === stringCamelCase("SubtensorModule") &&
      event.method === "MaxChildKeyTakeSet"
    )
    .forEach(({ event }) => {
      console.log("MaxChildKeyTakeSet:", event.data.toHuman());
    });
});

Version History

Version:

v195 block 3,791,350 1 args

v233 block 4,920,350 1 args

v252 block 5,163,656 1 args

v273 block 5,659,032 1 args

v290 block 5,947,548 1 args

v320 block 6,523,566 1 args Current

Runtime Info

View Source

Pallet Index: 7
Event Index: 45
First Version: v195
Current Version: v393

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