NXP-31254: Document file:content/digest and coldstorage:coldContent/d…

…igest index

README.md

@@ -31,19 +31,26 @@ This will build all the modules except _ci_ and generate the correspondent artif
 
 ## DB configuration
 
-The Cold Storage addon periodically checks the documents on which a retrieve has been requested. This scan is scheduled [every hour](https://github.com/nuxeo/nuxeo-coldstorage/blob/lts-2021/nuxeo-coldstorage-package/src/main/resources/install/templates/coldstorage/nuxeo.defaults#L7) by default.
-
-This check is done with the following query:
-```
-SELECT * FROM Document WHERE ecm:mixinType = 'ColdStorage' AND coldstorage:beingRetrieved = 1
-```
-An index on the `coldstorage:beingRetrieved` property is defined by this [contribution](https://github.com/nuxeo/nuxeo-coldstorage/blob/lts-2021/nuxeo-coldstorage/src/main/resources/OSGI-INF/coldstorage-core-types-contrib.xml#L7) to optimize the execution of this query. However, in case of an existing very large repository where such index creation could take too long, consider creating a partial index prior to starting Nuxeo with the Cold Storage addon installed. For example, on MongoDB:
-```
-db.default.createIndex(
-   { "coldstorage:beingRetrieved": 1 },
-   { partialFilterExpression: { "coldstorage:beingRetrieved": true } }
-)
-```
+Create the following db indexes for an optimal functioning of the addon:
+ - `coldstorage:beingRetrieved`
+ - `coldstorage:coldContent/digest`
+ - `file:content/digest`
+
+ Typically on MongoDB:
+ ```
+ db.default.createIndex(
+    { "coldstorage:beingRetrieved": 1 },
+    { partialFilterExpression: { "coldstorage:beingRetrieved": true } }
+ );
+
+ db.default.createIndex(
+    { "file:content/digest": 1 }
+ );
+
+ db.default.createIndex(
+    { "coldstorage:coldContent/digest": 1 }
+ );
+ ```
 
 ### Frontend Contribution