set_childkey_take

Call v195 → current #75

Sets the take rate for a child hotkey .

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Call Workflow

set_childkey_take

1. Validation

Signature, nonce, mortality, fees

Signature

Nonce

Mortality

Fee payment

2. Pre-dispatch

Permission & state checks

Permission checks

State validation

3. Dispatch

Execute logic, modify state

ChildKeyTakeSet ChildkeyTake LastTxBlockChildKeyTake

4. Post-dispatch

Final result & fee settlement

ExtrinsicSuccess

Fees settled

Svelte Flow

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Used by: validatorsminersdevelopers

The Big Picture

As a child key operator, you use stake power delegated from parents. Childkey take determines how you split earnings - you keep the take percentage, the rest goes to parents. Higher take means more for you, but parents might choose different children. It's a competitive market for stake utilization.

Why This Matters

Take rate is your compensation as a child operator. Set it too high, and parents will allocate stake elsewhere. Set it too low, and you're not fairly compensated for your work. Find the market-clearing rate that attracts sufficient stake while covering your costs.

Example Scenario

You're a child miner using stake from 3 parents. Current take is 20% but you want 25% to cover increased costs. Call set_childkey_take(hotkey=your_hotkey, netuid=1, take=0.25). Your take increases - parents now receive 75% of your earnings instead of 80%.

Common Questions

Do parents approve my take rate?: No - you set it unilaterally. But parents can reallocate stake to other children if they don't like your rate. It's market-driven, not permission-based.
What's the maximum childkey take?: Set by network parameter (MaxChildKeyTake). Typically capped to prevent exploitative rates. Check current network parameters for the exact limit.
How often can I change my take?: Rate-limited to prevent manipulation. You can't change every block. Check TxChildKeyTakeRateLimit for the current cooldown period.

Use Cases

Negotiate compensation for using parent's stake power
Adjust take rate as mining conditions change
Attract or discourage parent-child relationships
Balance operator compensation with parent returns

From Chain Metadata

Sets the childkey take for a given hotkey. This function allows a coldkey to set the childkey take for a given hotkey. The childkey take determines the proportion of stake that the hotkey keeps for itself when distributing stake to its children.

Part of: Child Hotkeys

Input Parameters

#	Name	Type	Description
0	hotkey	AccountId	Hot wallet address (active operations) (hex -> SS58)
1	netuid	u16	Subnet/network identifier (0-65535)
2	take	u16	take (u16)

Permissions

Origin

Signed

Required Role

Any

Permission data inferred from metadata. May be incomplete.

Requirements

Caller owns child hotkey
Take within allowed range (MinChildKeyTake to MaxChildKeyTake)
Rate limit not exceeded

Effects

Events Emitted

ChildKeyTakeSet

Storage Modified

ChildkeyTake LastTxBlockChildKeyTake

Postconditions

ChildKeyTake updated
New take applies to future emissions

Side Effects

Affects child's share of allocated rewards
Changes parent's portion of child's earnings

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 });

// Build set_childkey_take call
const hotkey = "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY";
const netuid = 1;
const take = 0;

const call = api.tx[stringCamelCase("SubtensorModule")][stringCamelCase("set_childkey_take")](
  hotkey,
  netuid,
  take
);

Runtime Info

View Source

Pallet Index: 7
Call Index: 75
First Version: v195
Current Version: v393

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