docs(mdx): Date hierarchies

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

@@ -1325,6 +1325,16 @@ 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.
+
+These hierarchies include a Calendar hierarchy structure containing `Year`, `Quarter`, `Month`, `Week`, and `Day` levels, as well as Calendar Quarter of Year and Calendar Year hierarchies. They allow filtering data in Excel without needing to drill down or expand all levels, and enable combining Calendar Year or Calendar Quarter of Year as filters while placing other dimensions on the axis.
+
+| 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 +1840,5 @@ 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