setQueryData() => {copy: false}

[utftu]

Now the setData() method looks like this,

// Use prev data if an isDataEqual function is defined and returns `true`
if (this.options.isDataEqual?.(prevData, data)) {
  data = prevData as TData
} else if (this.options.structuralSharing !== false) {
  // Structurally share data between prev and new data if needed
  data = replaceEqualDeep(prevData, data)
}

but I would like to be able to use the setQueryData() method to set data without creating a deep copy by the library and disabling the structural sharing.

I suggest adding the copy field to the existing config

interface SetDataOptions {
  updatedAt?: number,
  copy?: boolean // new field
}

, which will mean that there is no need to create a deep copy. Then the setData() code should look like this

// Use prev data if an isDataEqual function is defined and returns `true`
if (this.options.isDataEqual?.(prevData, data)) {
  data = prevData as TData
} else if (this.options.structuralSharing !== false && options.copy !== false) {
  // Structurally share data between prev and new data if needed
  data = replaceEqualDeep(prevData, data)
}

and the call to setQueryData() will look like this

setQueryData(queryKey, data, {copy: false})

What is it for?

Now I am developing a library for normalizing the cache and a wrapper for react-query and I would like to eliminate the need to create a deep copy of the data, not counting that it wastes crumbs of performance, this behavior also does not allow having the same entities in different queries

[TkDodo]

Not sure that I fully understand the use-case, but why don't you just set structuralSharing: false ?