Merge branch 'master' into delete-dead-code-source

BlueBrain · Aug 24, 2023 · 3a2a755 · 3a2a755
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diff --git a/docs/src/main/paradox/docs/releases/v1.8-to-v1.9-migration.md b/docs/src/main/paradox/docs/releases/v1.8-to-v1.9-migration.md
@@ -22,4 +22,22 @@ Nexus Fusion also allows to restart the indexing for the different views.
 
 ## Composite views
 
-TODO
+The introduction of @ref:[partial reindexing](./v1.9-release-notes.md#partial-reindexing) for composite views required a model
+change of composite views.
+
+If your Nexus deployment relies on composite views or search, the following environment variable need to be set 
+when launching Delta v1.9 for the first time:
+
+* `MIGRATE_COMPOSITE_VIEWS`: true
+
+The following logs should appear in Delta:
+
+```
+2023-08-24 07:38:24 INFO  c.e.b.n.d.p.c.m.MigrateCompositeViews - Starting composite views migration
+2023-08-24 07:38:28 INFO  c.e.b.n.d.p.c.m.MigrateCompositeViews - '500' composite views events have been migrated
+2023-08-24 07:38:28 INFO  c.e.b.n.d.p.c.m.MigrateCompositeViews - '31' composite views states have been migrated
+2023-08-24 07:38:28 INFO  c.e.b.n.d.p.c.m.MigrateCompositeViews - '62' composite views states have been migrated
+2023-08-24 07:38:34 INFO  c.e.b.n.d.p.c.m.MigrateCompositeViews - Composite views migration is now complete with (500,62) events/states updated
+```
+
+After this completes, the environment variable can be removed and Delta restarted.
diff --git a/docs/src/main/paradox/docs/releases/v1.9-release-notes.md b/docs/src/main/paradox/docs/releases/v1.9-release-notes.md
@@ -2,7 +2,8 @@
 
 TODO add link to full changes on github
 
-TODO add potential migration page
+If you are currently using Nexus Delta from 1.8.x, please
+visit the @ref:[migration instructions](v1.8-to-v1.9-migration.md) for the necessary steps to successfully upgrade.
 
 ## Nexus Delta
 
@@ -47,6 +48,28 @@ Indexing errors can now be listed and filtered for a given view.
 
 @ref:[More information](../delta/api/views/index.md#listing-indexing-failures)
 
+### Composite views
+
+To enhance performance of indexing of composite views, Nexus Delta introduces the following features.
+
+#### Batching queries to the intermediate space
+
+Construct queries to the intermediate space can now be batched.
+
+@ref:[More information](../delta/api/views/composite-view-api.md#batching-queries-to-the-intermediate-space)
+
+#### Partial reindexing
+
+When a composite view is updated, a diff is performed and only the necessary spaces are reindexed.
+
+For example, if a source is added/updated/removed, all the spaces (intermediate space and projection spaces) get reindexed.
+However if a projection is added/updated/removed, now only the space related to this projection is reindexed which reduces the
+number of operations and consequently speed up the indexing.
+
+Preserving the intermediate space also reduces the fragmentation of the Blazegraph journal.
+
+@ref:[More information](../delta/api/views/composite-view-api.md#batching-queries-to-the-intermediate-space)
+
 ### Elasticsearch Views
 
 The Elasticsearch mapping of an Elasticsearch View can be retrieved.