Source: Roblox Creator Hub · CC BY 4.0 · View source · Code samples: MIT Imported 2026-10-03. Formatting adapted for this site.
MemoryStoreHashMap
Inherits from: Instance → Object
Provides access to a hash map within MemoryStoreService. A hash map is a collection of items where string keys are associated with arbitrary values (up to the maximum allowed size -- see Memory Stores). The keys have no ordering guarantees.
Inherits from: Instance
Memory category: Instances
Tags: NotCreatable, NotReplicated
Methods
| Name | Type / Returns | Description |
|---|---|---|
| MemoryStoreHashMap:GetAsync | Variant | Retrieves the value of a key in the hash map. |
| MemoryStoreHashMap:ListItemsAsync | MemoryStoreHashMapPages | Returns a MemoryStoreHashMapPages object for enumerating through items in the hash map. |
| MemoryStoreHashMap:RemoveAsync | () | Removes an item from the hash map. |
| MemoryStoreHashMap:SetAsync | boolean | Sets the value of a key in the hash map. |
| MemoryStoreHashMap:UpdateAsync | Variant | Retrieves the value of a key from a hash map and lets you update it to a new value. |
Inherited from Instance
| Name | Type / Returns | Description |
|---|---|---|
| Instance:AddTag | () | Applies a tag to the instance. |
| Instance:children | Instances | Returns an array of the object's children. |
| Instance:ClearAllChildren | () | This method destroys all of an instance's children. |
| Instance:Clone | Instance | Create a copy of an instance and all its descendants, ignoring instances that are not Archivable. |
| Instance:clone | Instance | |
| Instance:Destroy | () | Sets the Instance.Parent property to nil, locks the Instance.Parent property, disconnects all connections, and calls Destroy() on all children. |
| Instance:destroy | () | |
| Instance:FindFirstAncestor | Instance? | Returns the first ancestor of the Instance whose Instance.Name is equal to the given name. |
| Instance:FindFirstAncestorOfClass | Instance? | Returns the first ancestor of the Instance whose Object.ClassName is equal to the given className. |
| Instance:FindFirstAncestorWhichIsA | Instance? | Returns the first ancestor of the Instance for whom Object:IsA() returns true for the given className. |
| Instance:FindFirstChild | Instance? | Returns the first child of the Instance found with the given name. |
| Instance:findFirstChild | Instance | |
| Instance:FindFirstChildOfClass | Instance? | Returns the first child of the Instance whose ClassName is equal to the given class name. |
| Instance:FindFirstChildWhichIsA | Instance? | Returns the first child of the Instance for whom Object:IsA() returns true for the given className. |
| Instance:FindFirstDescendant | Instance? | Returns the first descendant found with the given Instance.Name. |
| Instance:GetActor | Actor? | Returns the Actor associated with the Instance, if any. |
| Instance:GetAttribute | Variant | Returns the value which has been assigned to the given attribute name. |
| Instance:GetAttributeChangedSignal | RBXScriptSignal | Returns an event that fires when the given attribute changes. |
| Instance:GetAttributes | Dictionary | Returns a dictionary of the instance's attributes. |
| Instance:GetChildren | Instances | Returns an array containing all of the instance's children. |
| Instance:getChildren | Instances | |
| Instance:GetDebugId | string | Returns a coded string of the debug ID used internally by Roblox. |
| Instance:GetDescendants | Instances | Returns an array containing all of the descendants of the instance. |
| Instance:GetFullName | string | Returns a string describing the instance's ancestry. |
| Instance:GetStyled | Variant | Returns the styled or explicitly modified value of the specified property, or else the default property value if it hasn't been styled/modified. |
| Instance:GetStyledPropertyChangedSignal | RBXScriptSignal | Returns an event that fires when the given style property changes on the instance. |
| Instance:GetTags | Array | Gets an array of all tags applied to the instance. |
| Instance:HasTag | boolean | Check whether the instance has a given tag. |
| Instance:IsAncestorOf | boolean | Returns true if an Instance is an ancestor of the given descendant. |
| Instance:IsDescendantOf | boolean | Returns true if an Instance is a descendant of the given ancestor. |
| Instance:isDescendantOf | boolean | |
| Instance:IsPropertyModified | boolean | Returns true if the value stored in the specified property is not equal to the code-instantiated default. |
| Instance:QueryDescendants | Instances | Returns an array containing all descendants of the instance that match the selector string. |
| Instance:Remove | () | Sets the object's Parent to nil, and does the same for all its descendants. |
| Instance:remove | () | |
| Instance:RemoveTag | () | Removes a tag from the instance. |
| Instance:ResetPropertyToDefault | () | Resets a property to its default value. |
| Instance:SetAttribute | () | Sets the attribute with the given name to the given value. |
| Instance:WaitForChild | Instance | Returns the child of the Instance with the given name. If the child does not exist, it will yield the current thread until it does. |
Inherited from Object
| Name | Type / Returns | Description |
|---|---|---|
| Object:GetPropertyChangedSignal | RBXScriptSignal | Get an event that fires when a given property of the object changes. |
| Object:IsA | boolean | Returns true if an object's class matches or inherits from a given class. |
| Object:isA | boolean |
MemoryStoreHashMap:GetAsync
Retrieves the value of a key in the hash map.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| key | string | The key whose value you want to retrieve. |
Returns
| Type | Description |
|---|---|
| Variant | The value, or nil if the key doesn't exist. |
| Field | Value |
|---|---|
| tags | ["Yields"] |
| security | None |
| thread safety | Unsafe |
| capabilities | ["DataStore"] |
Code samples: View on Creator Hub (getting-data-hash-map-memory-store).
MemoryStoreHashMap:ListItemsAsync
Returns a MemoryStoreHashMapPages object for enumerating through items in the hash map. The valid range is 1 to 200 inclusive.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| count | int | Maximum possible number of items that can be returned. |
Returns
| Type | Description |
|---|---|
| MemoryStoreHashMapPages | A MemoryStoreHashMapPages instance that enumerates the items as MemoryStoreHashMapPages instances. |
| Field | Value |
|---|---|
| tags | ["Yields"] |
| security | None |
| thread safety | Unsafe |
| capabilities | ["DataStore"] |
Code samples: View on Creator Hub (listing-data-hash-map-memory-store).
MemoryStoreHashMap:RemoveAsync
Removes an item from the hash map.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| key | string | The key to remove. |
Returns
| Type | Description |
|---|---|
| () |
| Field | Value |
|---|---|
| tags | ["Yields"] |
| security | None |
| thread safety | Unsafe |
| capabilities | ["DataStore"] |
Code samples: View on Creator Hub (removing-data-hash-map-memory-store).
MemoryStoreHashMap:SetAsync
Sets the value of a key in the hash map, overwriting any existing value.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| key | string | The key whose value to set. | |
| value | Variant | The value to set. | |
| expiration | int64 | Item expiration in seconds, after which the item is automatically removed from the hash map. The maximum expiration time is 45 days (3,888,000 seconds). |
Returns
| Type | Description |
|---|---|
| boolean | true if the key already had a value that was overwritten, or false if the key was newly created. |
| Field | Value |
|---|---|
| tags | ["Yields"] |
| security | None |
| thread safety | Unsafe |
| capabilities | ["DataStore"] |
Code samples: View on Creator Hub (adding-data-hash-map-memory-store).
MemoryStoreHashMap:UpdateAsync
Retrieves the value of a key from a hash map and lets you update it to a new value.
This method accepts a callback function that retrieves the existing key value and passes it to a transform function, which returns the new value for the item, with these exceptions:
- If the key does not exist, the old value passed to the function is
nil. - If the function returns
nil, the update is canceled.
The new value is saved only if the key was not updated (for example, by a different game server) since the moment it was read. If the value changed in that time, the transform function is called again with the most recent item value. This cycle repeats until the value is saved successfully or the transform function returns nil to abort the operation.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
| key | string | The key whose value you want to update. | |
| transformFunction | Function | The transform function, which you provide. This function takes the old value as an input and returns the new value. | |
| expiration | int64 | Item expiration in seconds, after which the item is automatically removed from the hash map. The maximum expiration time is 45 days (3,888,000 seconds). |
Returns
| Type | Description |
|---|---|
| Variant | The last value returned by the transform function. |
| Field | Value |
|---|---|
| tags | ["Yields"] |
| security | None |
| thread safety | Unsafe |
| capabilities | ["DataStore"] |
Code samples: View on Creator Hub (updating-hash-map-memory-store).
Properties
Inherited from Instance
| Name | Type / Returns | Description |
|---|---|---|
| Instance.Archivable | boolean | Determines if an Instance and its descendants can be cloned using Instance:Clone(), and can be saved/published. |
| Instance.archivable | boolean | |
| Instance.Capabilities | SecurityCapabilities | The set of capabilities allowed to be used for scripts inside this container. |
| Instance.IsInSandbox | boolean | Indicates whether the instance is inside a sandboxed container. |
| Instance.Name | string | A non-unique identifier of the Instance. |
| Instance.Parent | Instance | Determines the hierarchical parent of the Instance. |
| Instance.PredictionMode | PredictionMode | Reflects the client-side prediction mode applied to the instance under server-authoritative physics. |
| Instance.RobloxLocked | boolean | A deprecated property that used to protect CoreGui objects. |
| Instance.Sandboxed | boolean | When enabled, the instance can only access abilities in its Capabilities list. |
| Instance.UniqueId | UniqueId | A unique identifier for the instance. |
Inherited from Object
| Name | Type / Returns | Description |
|---|---|---|
| Object.ClassName | string | A read-only string representing the class this Object belongs to. |
| Object.className | string |
Events
Inherited from Instance
| Name | Type / Returns | Description |
|---|---|---|
| Instance.AncestryChanged | Fires when the Instance.Parent property of this object or one of its ancestors is changed. | |
| Instance.AttributeChanged | Fires whenever an attribute is changed on the Instance. | |
| Instance.ChildAdded | Fires after an object is parented to this Instance. | |
| Instance.childAdded | ||
| Instance.ChildRemoved | Fires after a child is removed from this Instance. | |
| Instance.DescendantAdded | Fires after a descendant is added to the Instance. | |
| Instance.DescendantRemoving | Fires immediately before a descendant of the Instance is removed. | |
| Instance.Destroying | Fires immediately before (or is deferred until after) the instance is destroyed via Instance:Destroy(). | |
| Instance.StyledPropertiesChanged | Fires whenever any style property is changed on the instance, including when a property is set to nil. |
Inherited from Object
| Name | Type / Returns | Description |
|---|---|---|
| Object.Changed | Fires immediately after a property of the object changes, with some limitations. |