Removing tech-preview header and updating documentation for retrievers and RRF

docs/reference/search/retriever.asciidoc

@@ -1,8 +1,6 @@
 [[retriever]]
 === Retriever
 
-preview::["This functionality is in technical preview and may be changed or removed in a future release. The syntax will likely change before GA. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features."]
-
 A retriever is a specification to describe top documents returned from a
 search. A retriever replaces other elements of the <<search-search, search API>>
 that also return top documents such as <<query-dsl, `query`>> and
@@ -75,7 +73,7 @@ Collapses the top documents by a specified key into a single top document per ke
 ===== Restrictions
 
 When a retriever tree contains a compound retriever (a retriever with two or more child
-retrievers) *only* the query element is allowed.
+retrievers) the <<search-after, search after>> parameter is not supported.
 
 [discrete]
 [[standard-retriever-example]]
@@ -245,12 +243,6 @@ include::{es-ref-dir}/rest-api/common-parms.asciidoc[tag=rrf-rank-window-size]
 
 include::{es-ref-dir}/rest-api/common-parms.asciidoc[tag=rrf-filter]
 
-===== Restrictions
-
-An RRF retriever is a compound retriever. Child retrievers may not use
-elements that are restricted by having a compound retriever as part of
-the retriever tree.
-
 [discrete]
 [[rrf-retriever-example-hybrid]]
 ==== Example: Hybrid search
@@ -413,10 +405,6 @@ Applies the specified <<query-dsl-bool-query, boolean query filter>> to the chil
 If the child retriever already specifies any filters, then this top-level filter is applied in conjuction
 with the filter defined in the child retriever.
 
-===== Restrictions
-
-A text similarity re-ranker retriever is a compound retriever. Child retrievers may not use elements that are restricted by having a compound retriever as part of the retriever tree.
-
 [discrete]
 [[text-similarity-reranker-retriever-example-cohere]]
 ==== Example: Cohere Rerank

docs/reference/search/rrf.asciidoc

@@ -1,8 +1,6 @@
 [[rrf]]
 === Reciprocal rank fusion
 
-preview::["This functionality is in technical preview and may be changed or removed in a future release. The syntax will likely change before GA. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features."]
-
 https://plg.uwaterloo.ca/~gvcormac/cormacksigir09-rrf.pdf[Reciprocal rank fusion (RRF)]
 is a method for combining multiple result sets with different relevance indicators into a single result set.
 RRF requires no tuning, and the different relevance indicators do not have to be related to each other to achieve high-quality results.
@@ -95,19 +93,21 @@ The `rrf` retriever supports:
 
 * <<search-aggregations, aggregations>>
 * <<search-from-param, from>>
+* <<search-suggesters, suggesters>>
+* <<highlighting, highlighting>>
+* <<collapse-search-results, collapse>>
+* <<profiling-queries, profiling>>
 
 The `rrf` retriever does not currently support:
 
 * <<search-api-scroll-query-param, scroll>>
-* <<search-api-pit, point in time>>
 * <<search-sort-param, sort>>
 * <<rescore, rescore>>
-* <<search-suggesters, suggesters>>
-* <<highlighting, highlighting>>
-* <<collapse-search-results, collapse>>
-* <<profiling-queries, profiling>>
 
 Using unsupported features as part of a search with an `rrf` retriever results in an exception.
++
+IMPORTANT: It is best to avoid providing a <<search-api-pit, point in time>> as part of the request, as
+RRF creates one internally that is shared by all sub-retrievers to ensure consistent results.
 
 [[rrf-using-multiple-standard-retrievers]]
 ==== Reciprocal rank fusion using multiple standard retrievers

docs/reference/search/search-your-data/retrievers-overview.asciidoc

@@ -1,9 +1,7 @@
 [[retrievers-overview]]
 === Retrievers
 
-preview::[]
-
-A retriever is an abstraction that was added to the Search API in *8.14.0*.
+A retriever is an abstraction that was added to the Search API in *8.14.0* and was made GA in *8.16.0*.
 This abstraction enables the configuration of multi-stage retrieval pipelines within a single `_search` call.
 This simplifies your search application logic, because you no longer need to configure complex searches via multiple {es} calls or implement additional client-side logic to combine results from different queries.
 
@@ -32,8 +30,7 @@ with different relevance indicators into a single result set.
 An RRF retriever is a *compound retriever*, where its `filter` element is
 propagated to its sub retrievers.
 +
-Sub retrievers may not use elements that are restricted by having a compound retriever as part of the retriever tree.
-See the <<rrf-using-multiple-standard-retrievers,RRF documentation>> for detailed examples and information on how to use the RRF retriever.
+
 * <<text-similarity-reranker-retriever,*Text Similarity Re-ranker Retriever*>>. Used for <<semantic-reranking,semantic reranking>>.
 Requires first creating a `rerank` task using the <<put-inference-api,{es} Inference API>>.
 

server/src/main/java/org/elasticsearch/search/retriever/CompoundRetrieverBuilder.java

@@ -194,6 +194,9 @@ public ActionRequestValidationException validate(
                 validationException
             );
         }
+        for (RetrieverSource innerRetriever : innerRetrievers) {
+            validationException = innerRetriever.retriever().validate(source, validationException, allowPartialSearchResults);
+        }
         return validationException;
     }