docs(mdx): Date hierarchies (#10082)

Author: ovr

docs/pages/product/apis-integrations/mdx-api.mdx

@@ -53,6 +53,29 @@ directly to the upstream data source.
 - If some queries still go to the upstream data source, it should respond with a
 subsecond latency. Consider tuning the concurrency and quotas to achieve that.
 
+### Date hierarchies
+
+By default, the MDX API creates additional hierarchies for all [time dimensions][ref-time-dimensions] and organizing them in a separate folder called "Calendar" for each dimension.
+This creates a Calendar hierarchy structure containing `Year`, `Quarter`, `Month`, `Week`, and `Day` levels, as well as Calendar Quarter of Year and Calendar Year hierarchies.
+
+```
+- Dimension Calendar:
+  - Year
+  - Quarter
+  - Month
+  - Week
+  - Day
+- Dimension Calendar Quarter of Year:
+  - Quarter
+- Dimension Calendar Year
+  - Year
+```
+
+These hierarchies are particularly useful in Excel because they allow you to filter your data without needing to drill down or expand all levels.
+Additionally, you can combine Calendar Year or Calendar Quarter of Year as filters while placing other dimensions on the axis.
+
+You can set the `CUBE_MDX_CREATE_DATE_HIERARCHIES` environment variable to `false` to disable this behavior.
+
 ### Measure format
 
 The MDX API respects the [`format` parameter][ref-measure-format] of measures so that the
@@ -94,7 +117,7 @@ views:
 
 For historical reasons, the syntax shown above differ from how
 [hierarchies][ref-hierarchies] are supposed to be defined in the data model.
-This is going to be harmonized in the future. 
+This is going to be harmonized in the future.
 
 </InfoBox>
 
@@ -185,7 +208,7 @@ views:
 
 For historical reasons, the syntax shown above differ from how
 [folders][ref-folders] are supposed to be defined in the data model.
-This is going to be harmonized in the future. 
+This is going to be harmonized in the future.
 
 </InfoBox>
 
@@ -203,4 +226,4 @@ Authentication and authorization work the same as for the [SQL API](/product/api
 [ref-deployment]: /product/deployment/cloud/deployments
 [ref-pre-aggregations]: /product/caching/using-pre-aggregations
 [ref-rollup-only-mode]: /product/caching/using-pre-aggregations#rollup-only-mode
-[ref-measure-format]: /product/data-modeling/reference/measures#format
+[ref-measure-format]: /product/data-modeling/reference/measures#format

docs/pages/product/configuration/reference/environment-variables.mdx

@@ -1307,7 +1307,7 @@ If `true`, the DAX API will expose time dimensions as calendar hierarchies.
 
 ## `CUBE_XMLA_LANGUAGE`
 
-This variable is used to [configure the locale][ref-mdx-api-locale] for the [MDX API][ref-mdx-api]. 
+This variable is used to [configure the locale][ref-mdx-api-locale] for the [MDX API][ref-mdx-api].
 
 | Possible Values | Default in Development | Default in Production |
 | --------------- | ---------------------- | --------------------- |
@@ -1325,6 +1325,14 @@ CUBE_XMLA_LANGUAGE=nl-NL
 
 [link-lcid]: https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-lcid/70feba9f-294e-491e-b6eb-56532684c37f
 
+## `CUBE_MDX_CREATE_DATE_HIERARCHIES`
+
+If `true`, the [MDX API][ref-mdx-api] will automatically create additional hierarchies for all [time dimensions][ref-time-dimensions] and organize them in a separate "Calendar" folder for each dimension.
+
+| Possible Values | Default in Development | Default in Production |
+| --------------- | ---------------------- | --------------------- |
+| `true`, `false` | `true`                 | `true`                |
+
 ## `CUBEJS_NESTED_FOLDERS_DELIMITER`
 
 Specifies the delimiter used to flatten the names of nested [folder][ref-folders] in
@@ -1830,4 +1838,5 @@ The port for a Cube deployment to listen to API connections on.
 [ref-context-to-app-id]: /product/configuration/reference/config#context_to_app_id
 [ref-environments]: /product/workspace/environments
 [ref-mdx-api]: /product/apis-integrations/mdx-api
-[ref-mdx-api-locale]: /product/apis-integrations/mdx-api#measure-format
+[ref-mdx-api-locale]: /product/apis-integrations/mdx-api#measure-format
+[ref-time-dimensions]: /product/data-modeling/reference/dimensions#time