PoolKey Guide

PoolKey is a crucial struct in Uniswap V4 that uniquely identifies a liquidity pool. It encapsulates all the essential parameters that define a pool's characteristics.

Structure

struct PoolKey {
    Currency currency0;
    Currency currency1;
    uint24 fee;
    int24 tickSpacing;
    IHooks hooks;
}

Fields

Field Name	Type	Description
currency0	Currency	The lower currency of the pool, sorted numerically
currency1	Currency	The higher currency of the pool, sorted numerically
fee	uint24	The pool swap fee, capped at 1,000,000. If the first bit is 1, the pool has a dynamic fee
tickSpacing	int24	The spacing between ticks for the pool
hooks	IHooks	The address of the hooks contract associated with the pool

Important Notes

• The currency0 and currency1 fields are always sorted numerically, with currency0 being the lower value. This ensures consistent pool identification regardless of the order in which tokens are provided.
• The fee field can represent either a static fee or indicate that the pool uses a dynamic fee mechanism.
• The tickSpacing field determines the granularity of price ranges that can be used for liquidity provision.
• The hooks field is an interface of our Hooks that the PoolManager uses to call these functions