diff --git a/google/cloud/retail/v2/catalog.proto b/google/cloud/retail/v2/catalog.proto
index 20cd402c8..f449e9016 100644
--- a/google/cloud/retail/v2/catalog.proto
+++ b/google/cloud/retail/v2/catalog.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/google/cloud/retail/v2/catalog_service.proto b/google/cloud/retail/v2/catalog_service.proto
index 30858061b..41523ac80 100644
--- a/google/cloud/retail/v2/catalog_service.proto
+++ b/google/cloud/retail/v2/catalog_service.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -93,8 +93,8 @@ service CatalogService {
   //   {newBranch}.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc SetDefaultBranch(SetDefaultBranchRequest)
       returns (google.protobuf.Empty) {
     option (google.api.http) = {
@@ -109,8 +109,8 @@ service CatalogService {
   // method under a specified parent catalog.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc GetDefaultBranch(GetDefaultBranchRequest)
       returns (GetDefaultBranchResponse) {
     option (google.api.http) = {
diff --git a/google/cloud/retail/v2/common.proto b/google/cloud/retail/v2/common.proto
index e1e06f87c..afbdcd053 100644
--- a/google/cloud/retail/v2/common.proto
+++ b/google/cloud/retail/v2/common.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/google/cloud/retail/v2/completion_service.proto b/google/cloud/retail/v2/completion_service.proto
index 478dac63e..c18d67d68 100644
--- a/google/cloud/retail/v2/completion_service.proto
+++ b/google/cloud/retail/v2/completion_service.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -36,8 +36,8 @@ option ruby_package = "Google::Cloud::Retail::V2";
 // Auto-completion service for retail.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Contact Retail Support (retail-search-support@google.com) if you are
-// interested in using Retail Search.
+// Please submit a form [here](https://cloud.google.com/contact) to contact
+// cloud sales if you are interested in using Retail Search.
 service CompletionService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -46,8 +46,8 @@ service CompletionService {
   // Completes the specified prefix with keyword suggestions.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc CompleteQuery(CompleteQueryRequest) returns (CompleteQueryResponse) {
     option (google.api.http) = {
       get: "/v2/{catalog=projects/*/locations/*/catalogs/*}:completeQuery"
@@ -59,8 +59,8 @@ service CompletionService {
   // Request processing may be synchronous. Partial updating is not supported.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc ImportCompletionData(ImportCompletionDataRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -135,13 +135,15 @@ message CompleteQueryRequest {
   // * user-data
   //
   // * cloud-retail
-  //   This option is not automatically enabled. Before using cloud-retail,
-  //   contact retail-search-support@google.com first.
+  //   This option requires additional allowlisting. Before using cloud-retail,
+  //   contact Cloud Retail support team first.
   string dataset = 6;
 
-  // Completion max suggestions.
+  // Completion max suggestions. If left unset or set to 0, then will fallback
+  // to the configured value [CompletionConfig.max_suggestions][].
   //
-  // The maximum allowed max suggestions is 20. The default value is 20.
+  // The maximum allowed max suggestions is 20. If it is set higher, it will be
+  // capped by 20.
   int32 max_suggestions = 5;
 }
 
@@ -172,9 +174,9 @@ message CompleteQueryResponse {
   // performance.
   string attribution_token = 2;
 
-  // Matched recent searches of this user. This field is a restricted feature.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in enabling it.
+  // Matched recent searches of this user. The maximum number of recent searches
+  // is 10. This field is a restricted feature. Contact Retail Search support
+  // team if you are interested in enabling it.
   //
   // This feature is only available when
   // [CompleteQueryRequest.visitor_id][google.cloud.retail.v2.CompleteQueryRequest.visitor_id]
diff --git a/google/cloud/retail/v2/import_config.proto b/google/cloud/retail/v2/import_config.proto
index 1fb849daf..25170d4c2 100644
--- a/google/cloud/retail/v2/import_config.proto
+++ b/google/cloud/retail/v2/import_config.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -160,13 +160,13 @@ message ImportProductsRequest {
     // Can only be while using
     // [BigQuerySource][google.cloud.retail.v2.BigQuerySource].
     //
-    // Add the IAM permission “BigQuery Data Viewer” for
+    // Add the IAM permission "BigQuery Data Viewer" for
     // cloud-retail-customer-data-access@system.gserviceaccount.com before
     // using this feature otherwise an error is thrown.
     //
     // This feature is only available for users who have Retail Search enabled.
-    // Contact Retail Support (retail-search-support@google.com) if you are
-    // interested in using Retail Search.
+    // Please submit a form [here](https://cloud.google.com/contact) to contact
+    // cloud sales if you are interested in using Retail Search.
     FULL = 2;
   }
 
@@ -303,7 +303,7 @@ message CompletionDataInputConfig {
   oneof source {
     // Required. BigQuery input source.
     //
-    // Add the IAM permission “BigQuery Data Viewer” for
+    // Add the IAM permission "BigQuery Data Viewer" for
     // cloud-retail-customer-data-access@system.gserviceaccount.com before
     // using this feature otherwise an error is thrown.
     BigQuerySource big_query_source = 1
diff --git a/google/cloud/retail/v2/prediction_service.proto b/google/cloud/retail/v2/prediction_service.proto
index 067f872bf..da588a03c 100644
--- a/google/cloud/retail/v2/prediction_service.proto
+++ b/google/cloud/retail/v2/prediction_service.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/google/cloud/retail/v2/product.proto b/google/cloud/retail/v2/product.proto
index 746dc6259..eaefca4c8 100644
--- a/google/cloud/retail/v2/product.proto
+++ b/google/cloud/retail/v2/product.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -310,13 +310,9 @@ message Product {
   // This field needs to pass all below criteria, otherwise an INVALID_ARGUMENT
   // error is returned:
   //
-  // * Max entries count: 200 by default; 100 for
-  // [Type.VARIANT][google.cloud.retail.v2.Product.Type.VARIANT].
+  // * Max entries count: 200.
   // * The key must be a UTF-8 encoded string with a length limit of 128
   //   characters.
-  // * Max indexable entries count: 200 by default; 40 for
-  // [Type.VARIANT][google.cloud.retail.v2.Product.Type.VARIANT].
-  // * Max searchable entries count: 30.
   // * For indexable attribute, the key must match the pattern:
   //   [a-zA-Z0-9][a-zA-Z0-9_]*. For example, key0LikeThis or KEY_1_LIKE_THIS.
   map<string, CustomAttribute> attributes = 12;
@@ -426,7 +422,7 @@ message Product {
 
   // The material of the product. For example, "leather", "wooden".
   //
-  // A maximum of 5 values are allowed. Each value must be a UTF-8 encoded
+  // A maximum of 20 values are allowed. Each value must be a UTF-8 encoded
   // string with a length limit of 128 characters. Otherwise, an
   // INVALID_ARGUMENT error is returned.
   //
@@ -525,8 +521,12 @@ message Product {
   // * [name][google.cloud.retail.v2.Product.name]
   // * [color_info][google.cloud.retail.v2.Product.color_info]
   //
-  // Maximum number of paths is 20. Otherwise, an INVALID_ARGUMENT error is
+  // Maximum number of paths is 30. Otherwise, an INVALID_ARGUMENT error is
   // returned.
+  //
+  // Note: Returning more fields in
+  // [SearchResponse][google.cloud.retail.v2.SearchResponse] may increase
+  // response payload size and serving latency.
   google.protobuf.FieldMask retrievable_fields = 30;
 
   // Output only. Product variants grouped together on primary product which
diff --git a/google/cloud/retail/v2/product_service.proto b/google/cloud/retail/v2/product_service.proto
index dac78fbc5..3c381eb3e 100644
--- a/google/cloud/retail/v2/product_service.proto
+++ b/google/cloud/retail/v2/product_service.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -143,8 +143,8 @@ service ProductService {
   // [RemoveFulfillmentPlaces][google.cloud.retail.v2.ProductService.RemoveFulfillmentPlaces].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc SetInventory(SetInventoryRequest) returns (google.longrunning.Operation) {
     option (google.api.http) = {
       post: "/v2/{inventory.name=projects/*/locations/*/catalogs/*/branches/*/products/**}:setInventory"
@@ -170,8 +170,8 @@ service ProductService {
   // [ListProducts][google.cloud.retail.v2.ProductService.ListProducts].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc AddFulfillmentPlaces(AddFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -198,8 +198,8 @@ service ProductService {
   // [ListProducts][google.cloud.retail.v2.ProductService.ListProducts].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc RemoveFulfillmentPlaces(RemoveFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
diff --git a/google/cloud/retail/v2/purge_config.proto b/google/cloud/retail/v2/purge_config.proto
index 588bb39b7..6c8ce100f 100644
--- a/google/cloud/retail/v2/purge_config.proto
+++ b/google/cloud/retail/v2/purge_config.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/google/cloud/retail/v2/retail_v2.yaml b/google/cloud/retail/v2/retail_v2.yaml
index 5bc9b3326..2f26c7fe1 100644
--- a/google/cloud/retail/v2/retail_v2.yaml
+++ b/google/cloud/retail/v2/retail_v2.yaml
@@ -59,8 +59,8 @@ http:
   - selector: google.longrunning.Operations.GetOperation
     get: '/v2/{name=projects/*/locations/*/operations/*}'
     additional_bindings:
-    - get: '/v2/{name=projects/*/locations/*/catalogs/*/operations/*}'
     - get: '/v2/{name=projects/*/locations/*/catalogs/*/branches/*/operations/*}'
+    - get: '/v2/{name=projects/*/locations/*/catalogs/*/operations/*}'
   - selector: google.longrunning.Operations.ListOperations
     get: '/v2/{name=projects/*/locations/*}/operations'
     additional_bindings:
diff --git a/google/cloud/retail/v2/search_service.proto b/google/cloud/retail/v2/search_service.proto
index 4522d5466..acc6010c5 100644
--- a/google/cloud/retail/v2/search_service.proto
+++ b/google/cloud/retail/v2/search_service.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -39,8 +39,8 @@ option ruby_package = "Google::Cloud::Retail::V2";
 // Service for search.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Contact Retail Support (retail-search-support@google.com) if you are
-// interested in using Retail Search.
+// Please submit a form [here](https://cloud.google.com/contact) to contact
+// cloud sales if you are interested in using Retail Search.
 service SearchService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -49,8 +49,8 @@ service SearchService {
   // Performs a search.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc Search(SearchRequest) returns (SearchResponse) {
     option (google.api.http) = {
       post: "/v2/{placement=projects/*/locations/*/catalogs/*/placements/*}:search"
@@ -74,35 +74,35 @@ message SearchRequest {
       // [FacetKey.query][google.cloud.retail.v2.SearchRequest.FacetSpec.FacetKey.query]
       // is not specified:
       //
-      // Textual facet keys:
-      // * brands
-      // * categories
-      // * genders
-      // * ageGroups
-      // * availability
-      // * colorFamilies
-      // * colors
-      // * sizes
-      // * materials
-      // * patterns
-      // * conditions
-      // * attributes.key
-      // * pickupInStore
-      // * shipToStore
-      // * sameDayDelivery
-      // * nextDayDelivery
-      // * customFulfillment1
-      // * customFulfillment2
-      // * customFulfillment3
-      // * customFulfillment4
-      // * customFulfillment5
+      // * textual_field =
+      //     * "brands"
+      //     * "categories"
+      //     * "genders"
+      //     * "ageGroups"
+      //     * "availability"
+      //     * "colorFamilies"
+      //     * "colors"
+      //     * "sizes"
+      //     * "materials"
+      //     * "patterns"
+      //     * "conditions"
+      //     * "attributes.key"
+      //     * "pickupInStore"
+      //     * "shipToStore"
+      //     * "sameDayDelivery"
+      //     * "nextDayDelivery"
+      //     * "customFulfillment1"
+      //     * "customFulfillment2"
+      //     * "customFulfillment3"
+      //     * "customFulfillment4"
+      //     * "customFulfillment5"
       //
-      // Numeric facet keys:
-      // * price
-      // * discount
-      // * rating
-      // * ratingCount
-      // * attributes.key
+      // * numerical_field =
+      //     * "price"
+      //     * "discount"
+      //     * "rating"
+      //     * "ratingCount"
+      //     * "attributes.key"
       string key = 1 [(google.api.field_behavior) = REQUIRED];
 
       // Set only if values should be bucketized into intervals. Must be set
@@ -166,7 +166,8 @@ message SearchRequest {
       // order](https://en.wikipedia.org/wiki/Natural_sort_order); numerical
       // intervals are sorted in the order given by
       // [FacetSpec.FacetKey.intervals][google.cloud.retail.v2.SearchRequest.FacetSpec.FacetKey.intervals];
-      // [FulfillmentInfo.ids][] are sorted in the order given by
+      // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+      // are sorted in the order given by
       // [FacetSpec.FacetKey.restricted_values][google.cloud.retail.v2.SearchRequest.FacetSpec.FacetKey.restricted_values].
       string order_by = 4;
 
@@ -287,12 +288,11 @@ message SearchRequest {
       // Examples:
       //
       // * To boost products with product ID "product_1" or "product_2", and
-      // color "Red" or "Blue":
-      //   ```
-      //   (id: ANY("product_1", "product_2"))
-      //   AND
-      //   (colorFamilies: ANY("Red", "Blue"))
-      //   ```
+      // color
+      //   "Red" or "Blue":<br>
+      //   *(id: ANY("product_1", "product_2"))<br>*
+      //   *AND<br>*
+      //   *(colorFamilies: ANY("Red", "Blue"))<br>*
       string condition = 1;
 
       // Strength of the condition boost, which should be in [-1, 1]. Negative
@@ -343,6 +343,11 @@ message SearchRequest {
     // The condition under which query expansion should occur. Default to
     // [Condition.DISABLED][google.cloud.retail.v2.SearchRequest.QueryExpansionSpec.Condition.DISABLED].
     Condition condition = 1;
+
+    // Whether to pin unexpanded results. If this field is set to true,
+    // unexpanded products are always at the top of the search results, followed
+    // by the expanded results.
+    bool pin_unexpanded_results = 2;
   }
 
   // Required. The resource name of the search engine placement, such as
@@ -409,7 +414,8 @@ message SearchRequest {
 
   // The filter syntax consists of an expression language for constructing a
   // predicate from one or more fields of the products being filtered. Filter
-  // expression is case-sensitive.
+  // expression is case-sensitive. See more details at this [user
+  // guide](/retail/private/docs/filter-and-order#filter).
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string filter = 10;
@@ -427,7 +433,9 @@ message SearchRequest {
 
   // The order in which products are returned. Products can be ordered by
   // a field in an [Product][google.cloud.retail.v2.Product] object. Leave it
-  // unset if ordered by relevance. OrderBy expression is case-sensitive.
+  // unset if ordered by relevance. OrderBy expression is case-sensitive. See
+  // more details at this [user
+  // guide](/retail/private/docs/filter-and-order#order).
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string order_by = 11;
@@ -441,16 +449,17 @@ message SearchRequest {
   // The specification for dynamically generated facets. Notice that only
   // textual facets can be dynamically generated.
   //
-  // This feature requires additional allowlisting. Contact Retail Support
-  // (retail-search-support@google.com) if you are interested in using dynamic
-  // facet feature.
+  // This feature requires additional allowlisting. Contact Retail Search
+  // support team if you are interested in using dynamic facet feature.
   DynamicFacetSpec dynamic_facet_spec = 21;
 
-  // Boost specification to boost certain products.
+  // Boost specification to boost certain products. See more details at this
+  // [user guide](/retail/private/docs/boosting).
   BoostSpec boost_spec = 13;
 
   // The query expansion specification that specifies the conditions under which
-  // query expansion will occur.
+  // query expansion will occur. See more details at this [user
+  // guide](/retail/private/docs/result-size#query_expansion).
   QueryExpansionSpec query_expansion_spec = 14;
 
   // The keys to fetch and rollup the matching
@@ -462,10 +471,9 @@ message SearchRequest {
   // [Product][google.cloud.retail.v2.Product]s attributes will lead to extra
   // query latency. Maximum number of keys is 10.
   //
-  // For
-  // [Product.fulfillment_info][google.cloud.retail.v2.Product.fulfillment_info],
-  // a fulfillment type and a fulfillment ID must be provided in the format of
-  // "fulfillmentType.filfillmentId". E.g., in "pickupInStore.store123",
+  // For [FulfillmentInfo][google.cloud.retail.v2.FulfillmentInfo], a
+  // fulfillment type and a fulfillment ID must be provided in the format of
+  // "fulfillmentType.fulfillmentId". E.g., in "pickupInStore.store123",
   // "pickupInStore" is fulfillment type and "store123" is the store ID.
   //
   // Supported keys are:
@@ -476,24 +484,42 @@ message SearchRequest {
   // * discount
   // * attributes.key, where key is any key in the
   //   [Product.attributes][google.cloud.retail.v2.Product.attributes] map.
-  // * pickupInStore.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.PICKUP_IN_STORE][].
-  // * shipToStore.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.SHIP_TO_STORE][].
-  // * sameDayDelivery.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.SAME_DAY_DELIVERY][].
-  // * nextDayDelivery.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.NEXT_DAY_DELIVERY][].
-  // * customFulfillment1.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_1][].
-  // * customFulfillment2.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_2][].
-  // * customFulfillment3.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_3][].
-  // * customFulfillment4.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_4][].
-  // * customFulfillment5.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_5][].
+  // * pickupInStore.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "pickup-in-store".
+  // * shipToStore.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "ship-to-store".
+  // * sameDayDelivery.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "same-day-delivery".
+  // * nextDayDelivery.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "next-day-delivery".
+  // * customFulfillment1.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "custom-type-1".
+  // * customFulfillment2.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "custom-type-2".
+  // * customFulfillment3.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "custom-type-3".
+  // * customFulfillment4.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "custom-type-4".
+  // * customFulfillment5.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2.FulfillmentInfo.type]
+  //   "custom-type-5".
   //
   // If this field is set to an invalid value other than these, an
   // INVALID_ARGUMENT error is returned.
@@ -583,10 +609,9 @@ message SearchResponse {
     //       }
     //     }
     //
-    // For
-    // [Product.fulfillment_info][google.cloud.retail.v2.Product.fulfillment_info],
-    // the rollup values is a double value with type
-    // [google.protobuf.Value][google.protobuf.Value]. For example:
+    // For [FulfillmentInfo][google.cloud.retail.v2.FulfillmentInfo], the rollup
+    // values is a double value with type
+    // [google.protobuf.Value][google.protobuf.Value]. For example,
     // `{key: "pickupInStore.store1" value { number_value: 10 }}` means a there
     // are 10 variants in this product are available in the store "store1".
     map<string, google.protobuf.Value> variant_rollup_values = 5;
@@ -625,6 +650,11 @@ message SearchResponse {
   message QueryExpansionInfo {
     // Bool describing whether query expansion has occurred.
     bool expanded_query = 1;
+
+    // Number of pinned results. This field will only be set when expansion
+    // happens and [SearchRequest.query_expansion_spec.pin_unexpanded_results][]
+    // is set to true.
+    int64 pinned_result_count = 2;
   }
 
   // A list of matched items. The order represents the ranking.
diff --git a/google/cloud/retail/v2/user_event.proto b/google/cloud/retail/v2/user_event.proto
index 7534edf3d..e4bb810b1 100644
--- a/google/cloud/retail/v2/user_event.proto
+++ b/google/cloud/retail/v2/user_event.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -258,9 +258,21 @@ message UserEvent {
 message ProductDetail {
   // Required. [Product][google.cloud.retail.v2.Product] information.
   //
-  // Only [Product.id][google.cloud.retail.v2.Product.id] field is used when
-  // ingesting an event, all other product fields are ignored as we will look
-  // them up from the catalog.
+  // Required field(s):
+  //
+  // * [Product.id][google.cloud.retail.v2.Product.id]
+  //
+  // Optional override field(s):
+  //
+  // * [Product.price_info][google.cloud.retail.v2.Product.price_info]
+  //
+  // If any supported optional fields are provided, we will treat them as a full
+  // override when looking up product information from the catalog. Thus, it is
+  // important to ensure that the overriding fields are accurate and
+  // complete.
+  //
+  // All other product fields are ignored and instead populated via catalog
+  // lookup after event ingestion.
   Product product = 1 [(google.api.field_behavior) = REQUIRED];
 
   // Quantity of the product associated with the user event.
diff --git a/google/cloud/retail/v2/user_event_service.proto b/google/cloud/retail/v2/user_event_service.proto
index 4dbd1dc7f..2d48a511d 100644
--- a/google/cloud/retail/v2/user_event_service.proto
+++ b/google/cloud/retail/v2/user_event_service.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/google/cloud/retail/v2alpha/catalog.proto b/google/cloud/retail/v2alpha/catalog.proto
index 189232995..63c09331d 100644
--- a/google/cloud/retail/v2alpha/catalog.proto
+++ b/google/cloud/retail/v2alpha/catalog.proto
@@ -104,7 +104,7 @@ message MerchantCenterLink {
 
   // String representing the destination to import for, all if left empty.
   // List of possible values can be found here.
-  // [https://support.google.com/merchants/answer/7501026?hl=en]
+  // [https://support.google.com/merchants/answer/7501026]
   // List of allowed string values:
   // "shopping-ads", "buy-on-google-listings", "display-ads", "local-inventory
   // -ads", "free-listings", "free-local-listings"
diff --git a/google/cloud/retail/v2alpha/catalog_service.proto b/google/cloud/retail/v2alpha/catalog_service.proto
index 59f839523..ac77b9240 100644
--- a/google/cloud/retail/v2alpha/catalog_service.proto
+++ b/google/cloud/retail/v2alpha/catalog_service.proto
@@ -93,8 +93,8 @@ service CatalogService {
   //   {newBranch}.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc SetDefaultBranch(SetDefaultBranchRequest)
       returns (google.protobuf.Empty) {
     option (google.api.http) = {
@@ -109,8 +109,8 @@ service CatalogService {
   // method under a specified parent catalog.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc GetDefaultBranch(GetDefaultBranchRequest)
       returns (GetDefaultBranchResponse) {
     option (google.api.http) = {
diff --git a/google/cloud/retail/v2alpha/completion_service.proto b/google/cloud/retail/v2alpha/completion_service.proto
index 60179156b..73476ff6c 100644
--- a/google/cloud/retail/v2alpha/completion_service.proto
+++ b/google/cloud/retail/v2alpha/completion_service.proto
@@ -36,8 +36,8 @@ option ruby_package = "Google::Cloud::Retail::V2alpha";
 // Auto-completion service for retail.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Contact Retail Support (retail-search-support@google.com) if you are
-// interested in using Retail Search.
+// Please submit a form [here](https://cloud.google.com/contact) to contact
+// cloud sales if you are interested in using Retail Search.
 service CompletionService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -46,8 +46,8 @@ service CompletionService {
   // Completes the specified prefix with keyword suggestions.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc CompleteQuery(CompleteQueryRequest) returns (CompleteQueryResponse) {
     option (google.api.http) = {
       get: "/v2alpha/{catalog=projects/*/locations/*/catalogs/*}:completeQuery"
@@ -59,8 +59,8 @@ service CompletionService {
   // Request processing may be synchronous. Partial updating is not supported.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc ImportCompletionData(ImportCompletionDataRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -125,22 +125,26 @@ message CompleteQueryRequest {
   string device_type = 4;
 
   // Determines which dataset to use for fetching completion. "user-data" will
-  // use the imported dataset through [ImportCompletionData][]. "cloud-retail"
-  // will use the dataset generated by cloud retail based on user events. If
-  // leave empty, it will use the "user-data".
+  // use the imported dataset through
+  // [CompletionService.ImportCompletionData][google.cloud.retail.v2alpha.CompletionService.ImportCompletionData].
+  // "cloud-retail" will use the dataset generated by cloud retail based on user
+  // events. If leave empty, it will use the "user-data".
   //
   // Current supported values:
   //
   // * user-data
   //
   // * cloud-retail
-  //   This option is not automatically enabled. Before using cloud-retail,
-  //   contact retail-search-support@google.com first.
+  //   This option requires additional allowlisting. Before using cloud-retail,
+  //   contact Cloud Retail support team first.
   string dataset = 6;
 
-  // Completion max suggestions.
+  // Completion max suggestions. If left unset or set to 0, then will fallback
+  // to the configured value
+  // [CompletionConfig.max_suggestions][google.cloud.retail.v2alpha.CompletionConfig.max_suggestions].
   //
-  // The maximum allowed max suggestions is 20. The default value is 20.
+  // The maximum allowed max suggestions is 20. If it is set higher, it will be
+  // capped by 20.
   int32 max_suggestions = 5;
 }
 
@@ -171,9 +175,9 @@ message CompleteQueryResponse {
   // performance.
   string attribution_token = 2;
 
-  // Matched recent searches of this user. This field is a restricted feature.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in enabling it.
+  // Matched recent searches of this user. The maximum number of recent searches
+  // is 10. This field is a restricted feature. Contact Retail Search support
+  // team if you are interested in enabling it.
   //
   // This feature is only available when
   // [CompleteQueryRequest.visitor_id][google.cloud.retail.v2alpha.CompleteQueryRequest.visitor_id]
diff --git a/google/cloud/retail/v2alpha/import_config.proto b/google/cloud/retail/v2alpha/import_config.proto
index b120083de..448390a23 100644
--- a/google/cloud/retail/v2alpha/import_config.proto
+++ b/google/cloud/retail/v2alpha/import_config.proto
@@ -160,13 +160,13 @@ message ImportProductsRequest {
     // Can only be while using
     // [BigQuerySource][google.cloud.retail.v2alpha.BigQuerySource].
     //
-    // Add the IAM permission “BigQuery Data Viewer” for
+    // Add the IAM permission "BigQuery Data Viewer" for
     // cloud-retail-customer-data-access@system.gserviceaccount.com before
     // using this feature otherwise an error is thrown.
     //
     // This feature is only available for users who have Retail Search enabled.
-    // Contact Retail Support (retail-search-support@google.com) if you are
-    // interested in using Retail Search.
+    // Please submit a form [here](https://cloud.google.com/contact) to contact
+    // cloud sales if you are interested in using Retail Search.
     FULL = 2;
   }
 
@@ -303,7 +303,7 @@ message CompletionDataInputConfig {
   oneof source {
     // Required. BigQuery input source.
     //
-    // Add the IAM permission “BigQuery Data Viewer” for
+    // Add the IAM permission "BigQuery Data Viewer" for
     // cloud-retail-customer-data-access@system.gserviceaccount.com before
     // using this feature otherwise an error is thrown.
     BigQuerySource big_query_source = 1
diff --git a/google/cloud/retail/v2alpha/product.proto b/google/cloud/retail/v2alpha/product.proto
index d6c536bc9..936e6d8b2 100644
--- a/google/cloud/retail/v2alpha/product.proto
+++ b/google/cloud/retail/v2alpha/product.proto
@@ -316,13 +316,9 @@ message Product {
   // This field needs to pass all below criteria, otherwise an INVALID_ARGUMENT
   // error is returned:
   //
-  // * Max entries count: 200 by default; 100 for
-  // [Type.VARIANT][google.cloud.retail.v2alpha.Product.Type.VARIANT].
+  // * Max entries count: 200.
   // * The key must be a UTF-8 encoded string with a length limit of 128
   //   characters.
-  // * Max indexable entries count: 200 by default; 40 for
-  // [Type.VARIANT][google.cloud.retail.v2alpha.Product.Type.VARIANT].
-  // * Max searchable entries count: 30.
   // * For indexable attribute, the key must match the pattern:
   //   [a-zA-Z0-9][a-zA-Z0-9_]*. For example, key0LikeThis or KEY_1_LIKE_THIS.
   map<string, CustomAttribute> attributes = 12;
@@ -432,7 +428,7 @@ message Product {
 
   // The material of the product. For example, "leather", "wooden".
   //
-  // A maximum of 5 values are allowed. Each value must be a UTF-8 encoded
+  // A maximum of 20 values are allowed. Each value must be a UTF-8 encoded
   // string with a length limit of 128 characters. Otherwise, an
   // INVALID_ARGUMENT error is returned.
   //
@@ -533,8 +529,12 @@ message Product {
   // * [name][google.cloud.retail.v2alpha.Product.name]
   // * [color_info][google.cloud.retail.v2alpha.Product.color_info]
   //
-  // Maximum number of paths is 20. Otherwise, an INVALID_ARGUMENT error is
+  // Maximum number of paths is 30. Otherwise, an INVALID_ARGUMENT error is
   // returned.
+  //
+  // Note: Returning more fields in
+  // [SearchResponse][google.cloud.retail.v2alpha.SearchResponse] may increase
+  // response payload size and serving latency.
   google.protobuf.FieldMask retrievable_fields = 30;
 
   // Output only. Product variants grouped together on primary product which
diff --git a/google/cloud/retail/v2alpha/product_service.proto b/google/cloud/retail/v2alpha/product_service.proto
index 89f59e490..4590a90b5 100644
--- a/google/cloud/retail/v2alpha/product_service.proto
+++ b/google/cloud/retail/v2alpha/product_service.proto
@@ -146,8 +146,8 @@ service ProductService {
   // [RemoveFulfillmentPlaces][google.cloud.retail.v2alpha.ProductService.RemoveFulfillmentPlaces].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc SetInventory(SetInventoryRequest) returns (google.longrunning.Operation) {
     option (google.api.http) = {
       post: "/v2alpha/{inventory.name=projects/*/locations/*/catalogs/*/branches/*/products/**}:setInventory"
@@ -173,8 +173,8 @@ service ProductService {
   // [ListProducts][google.cloud.retail.v2alpha.ProductService.ListProducts].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc AddFulfillmentPlaces(AddFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -201,8 +201,8 @@ service ProductService {
   // [ListProducts][google.cloud.retail.v2alpha.ProductService.ListProducts].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc RemoveFulfillmentPlaces(RemoveFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
diff --git a/google/cloud/retail/v2alpha/search_service.proto b/google/cloud/retail/v2alpha/search_service.proto
index 109b93992..250eeada6 100644
--- a/google/cloud/retail/v2alpha/search_service.proto
+++ b/google/cloud/retail/v2alpha/search_service.proto
@@ -39,8 +39,8 @@ option ruby_package = "Google::Cloud::Retail::V2alpha";
 // Service for search.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Contact Retail Support (retail-search-support@google.com) if you are
-// interested in using Retail Search.
+// Please submit a form [here](https://cloud.google.com/contact) to contact
+// cloud sales if you are interested in using Retail Search.
 service SearchService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -49,8 +49,8 @@ service SearchService {
   // Performs a search.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc Search(SearchRequest) returns (SearchResponse) {
     option (google.api.http) = {
       post: "/v2alpha/{placement=projects/*/locations/*/catalogs/*/placements/*}:search"
@@ -68,42 +68,42 @@ message SearchRequest {
     // Specifies how a facet is computed.
     message FacetKey {
       // Required. Supported textual and numerical facet keys in
-      // [Product][google.cloud.retail.v2alpha.Product] object, over which the
-      // facet values are computed. Facet key is case-sensitive.
+      // [Product][google.cloud.retail.v2.Product] object, over which the facet
+      // values are computed. Facet key is case-sensitive.
       //
       // Allowed facet keys when
-      // [FacetKey.query][google.cloud.retail.v2alpha.SearchRequest.FacetSpec.FacetKey.query]
+      // [FacetKey.query][google.cloud.retail.v2.SearchRequest.FacetSpec.FacetKey.query]
       // is not specified:
       //
-      // Textual facet keys:
-      // * brands
-      // * categories
-      // * genders
-      // * ageGroups
-      // * availability
-      // * colorFamilies
-      // * colors
-      // * sizes
-      // * materials
-      // * patterns
-      // * conditions
-      // * attributes.key
-      // * pickupInStore
-      // * shipToStore
-      // * sameDayDelivery
-      // * nextDayDelivery
-      // * customFulfillment1
-      // * customFulfillment2
-      // * customFulfillment3
-      // * customFulfillment4
-      // * customFulfillment5
+      // * textual_field =
+      //     * "brands"
+      //     * "categories"
+      //     * "genders"
+      //     * "ageGroups"
+      //     * "availability"
+      //     * "colorFamilies"
+      //     * "colors"
+      //     * "sizes"
+      //     * "materials"
+      //     * "patterns"
+      //     * "conditions"
+      //     * "attributes.key"
+      //     * "pickupInStore"
+      //     * "shipToStore"
+      //     * "sameDayDelivery"
+      //     * "nextDayDelivery"
+      //     * "customFulfillment1"
+      //     * "customFulfillment2"
+      //     * "customFulfillment3"
+      //     * "customFulfillment4"
+      //     * "customFulfillment5"
       //
-      // Numeric facet keys:
-      // * price
-      // * discount
-      // * rating
-      // * ratingCount
-      // * attributes.key
+      // * numerical_field =
+      //     * "price"
+      //     * "discount"
+      //     * "rating"
+      //     * "ratingCount"
+      //     * "attributes.key"
       string key = 1 [(google.api.field_behavior) = REQUIRED];
 
       // Set only if values should be bucketized into intervals. Must be set
@@ -167,7 +167,8 @@ message SearchRequest {
       // order](https://en.wikipedia.org/wiki/Natural_sort_order); numerical
       // intervals are sorted in the order given by
       // [FacetSpec.FacetKey.intervals][google.cloud.retail.v2alpha.SearchRequest.FacetSpec.FacetKey.intervals];
-      // [FulfillmentInfo.ids][] are sorted in the order given by
+      // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+      // are sorted in the order given by
       // [FacetSpec.FacetKey.restricted_values][google.cloud.retail.v2alpha.SearchRequest.FacetSpec.FacetKey.restricted_values].
       string order_by = 4;
 
@@ -289,12 +290,11 @@ message SearchRequest {
       // Examples:
       //
       // * To boost products with product ID "product_1" or "product_2", and
-      // color "Red" or "Blue":
-      //   ```
-      //   (id: ANY("product_1", "product_2"))
-      //   AND
-      //   (colorFamilies: ANY("Red", "Blue"))
-      //   ```
+      // color
+      //   "Red" or "Blue":<br>
+      //   *(id: ANY("product_1", "product_2"))<br>*
+      //   *AND<br>*
+      //   *(colorFamilies: ANY("Red", "Blue"))<br>*
       string condition = 1;
 
       // Strength of the condition boost, which should be in [-1, 1]. Negative
@@ -345,6 +345,11 @@ message SearchRequest {
     // The condition under which query expansion should occur. Default to
     // [Condition.DISABLED][google.cloud.retail.v2alpha.SearchRequest.QueryExpansionSpec.Condition.DISABLED].
     Condition condition = 1;
+
+    // Whether to pin unexpanded results. If this field is set to true,
+    // unexpanded products are always at the top of the search results, followed
+    // by the expanded results.
+    bool pin_unexpanded_results = 2;
   }
 
   // The relevance threshold of the search results. The higher relevance
@@ -433,7 +438,8 @@ message SearchRequest {
 
   // The filter syntax consists of an expression language for constructing a
   // predicate from one or more fields of the products being filtered. Filter
-  // expression is case-sensitive.
+  // expression is case-sensitive. See more details at this [user
+  // guide](/retail/private/docs/filter-and-order#filter).
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string filter = 10;
@@ -452,7 +458,9 @@ message SearchRequest {
 
   // The order in which products are returned. Products can be ordered by
   // a field in an [Product][google.cloud.retail.v2alpha.Product] object. Leave
-  // it unset if ordered by relevance. OrderBy expression is case-sensitive.
+  // it unset if ordered by relevance. OrderBy expression is case-sensitive. See
+  // more details at this [user
+  // guide](/retail/private/docs/filter-and-order#order).
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string order_by = 11;
@@ -466,16 +474,17 @@ message SearchRequest {
   // The specification for dynamically generated facets. Notice that only
   // textual facets can be dynamically generated.
   //
-  // This feature requires additional allowlisting. Contact Retail Support
-  // (retail-search-support@google.com) if you are interested in using dynamic
-  // facet feature.
+  // This feature requires additional allowlisting. Contact Retail Search
+  // support team if you are interested in using dynamic facet feature.
   DynamicFacetSpec dynamic_facet_spec = 21;
 
-  // Boost specification to boost certain products.
+  // Boost specification to boost certain products. See more details at this
+  // [user guide](/retail/private/docs/boosting).
   BoostSpec boost_spec = 13;
 
   // The query expansion specification that specifies the conditions under which
-  // query expansion will occur.
+  // query expansion will occur. See more details at this [user
+  // guide](/retail/private/docs/result-size#query_expansion).
   QueryExpansionSpec query_expansion_spec = 14;
 
   // The relevance threshold of the search results.
@@ -483,7 +492,8 @@ message SearchRequest {
   // Defaults to
   // [RelevanceThreshold.HIGH][google.cloud.retail.v2alpha.SearchRequest.RelevanceThreshold.HIGH],
   // which means only the most relevant results are shown, and the least number
-  // of results are returned.
+  // of results are returned. See more details at this [user
+  // guide](/retail/private/docs/result-size#relevance_thresholding).
   RelevanceThreshold relevance_threshold = 15;
 
   // The keys to fetch and rollup the matching
@@ -497,10 +507,9 @@ message SearchRequest {
   // [Product][google.cloud.retail.v2alpha.Product]s attributes will lead to
   // extra query latency. Maximum number of keys is 10.
   //
-  // For
-  // [Product.fulfillment_info][google.cloud.retail.v2alpha.Product.fulfillment_info],
-  // a fulfillment type and a fulfillment ID must be provided in the format of
-  // "fulfillmentType.filfillmentId". E.g., in "pickupInStore.store123",
+  // For [FulfillmentInfo][google.cloud.retail.v2alpha.FulfillmentInfo], a
+  // fulfillment type and a fulfillment ID must be provided in the format of
+  // "fulfillmentType.fulfillmentId". E.g., in "pickupInStore.store123",
   // "pickupInStore" is fulfillment type and "store123" is the store ID.
   //
   // Supported keys are:
@@ -511,24 +520,51 @@ message SearchRequest {
   // * discount
   // * attributes.key, where key is any key in the
   //   [Product.attributes][google.cloud.retail.v2alpha.Product.attributes] map.
-  // * pickupInStore.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.PICKUP_IN_STORE][].
-  // * shipToStore.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.SHIP_TO_STORE][].
-  // * sameDayDelivery.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.SAME_DAY_DELIVERY][].
-  // * nextDayDelivery.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.NEXT_DAY_DELIVERY][].
-  // * customFulfillment1.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_1][].
-  // * customFulfillment2.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_2][].
-  // * customFulfillment3.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_3][].
-  // * customFulfillment4.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_4][].
-  // * customFulfillment5.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_5][].
+  // * pickupInStore.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "pickup-in-store".
+  // * shipToStore.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "ship-to-store".
+  // * sameDayDelivery.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "same-day-delivery".
+  // * nextDayDelivery.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "next-day-delivery".
+  // * customFulfillment1.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "custom-type-1".
+  // * customFulfillment2.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "custom-type-2".
+  // * customFulfillment3.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "custom-type-3".
+  // * customFulfillment4.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "custom-type-4".
+  // * customFulfillment5.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2alpha.FulfillmentInfo.place_ids]
+  // for
+  // [FulfillmentInfo.type][google.cloud.retail.v2alpha.FulfillmentInfo.type]
+  //   "custom-type-5".
   //
   // If this field is set to an invalid value other than these, an
   // INVALID_ARGUMENT error is returned.
@@ -620,9 +656,8 @@ message SearchResponse {
     //       }
     //     }
     //
-    // For
-    // [Product.fulfillment_info][google.cloud.retail.v2alpha.Product.fulfillment_info],
-    // the rollup values is a double value with type
+    // For [FulfillmentInfo][google.cloud.retail.v2alpha.FulfillmentInfo], the
+    // rollup values is a double value with type
     // [google.protobuf.Value][google.protobuf.Value]. For example,
     // `{key: "pickupInStore.store1" value { number_value: 10 }}` means a there
     // are 10 variants in this product are available in the store "store1".
@@ -662,6 +697,11 @@ message SearchResponse {
   message QueryExpansionInfo {
     // Bool describing whether query expansion has occurred.
     bool expanded_query = 1;
+
+    // Number of pinned results. This field will only be set when expansion
+    // happens and [SearchRequest.query_expansion_spec.pin_unexpanded_results][]
+    // is set to true.
+    int64 pinned_result_count = 2;
   }
 
   // A list of matched items. The order represents the ranking.
diff --git a/google/cloud/retail/v2alpha/user_event.proto b/google/cloud/retail/v2alpha/user_event.proto
index 99a2941e3..7ea735756 100644
--- a/google/cloud/retail/v2alpha/user_event.proto
+++ b/google/cloud/retail/v2alpha/user_event.proto
@@ -261,9 +261,21 @@ message UserEvent {
 message ProductDetail {
   // Required. [Product][google.cloud.retail.v2alpha.Product] information.
   //
-  // Only [Product.id][google.cloud.retail.v2alpha.Product.id] field is used
-  // when ingesting an event, all other product fields are ignored as we will
-  // look them up from the catalog.
+  // Required field(s):
+  //
+  // * [Product.id][google.cloud.retail.v2alpha.Product.id]
+  //
+  // Optional override field(s):
+  //
+  // * [Product.price_info][google.cloud.retail.v2alpha.Product.price_info]
+  //
+  // If any supported optional fields are provided, we will treat them as a full
+  // override when looking up product information from the catalog. Thus, it is
+  // important to ensure that the overriding fields are accurate and
+  // complete.
+  //
+  // All other product fields are ignored and instead populated via catalog
+  // lookup after event ingestion.
   Product product = 1 [(google.api.field_behavior) = REQUIRED];
 
   // Quantity of the product associated with the user event.
diff --git a/google/cloud/retail/v2beta/catalog_service.proto b/google/cloud/retail/v2beta/catalog_service.proto
index 0d499d383..c87e2ba96 100644
--- a/google/cloud/retail/v2beta/catalog_service.proto
+++ b/google/cloud/retail/v2beta/catalog_service.proto
@@ -93,8 +93,8 @@ service CatalogService {
   //   {newBranch}.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc SetDefaultBranch(SetDefaultBranchRequest)
       returns (google.protobuf.Empty) {
     option (google.api.http) = {
@@ -109,8 +109,8 @@ service CatalogService {
   // method under a specified parent catalog.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc GetDefaultBranch(GetDefaultBranchRequest)
       returns (GetDefaultBranchResponse) {
     option (google.api.http) = {
diff --git a/google/cloud/retail/v2beta/completion_service.proto b/google/cloud/retail/v2beta/completion_service.proto
index bb574675b..cd9de876b 100644
--- a/google/cloud/retail/v2beta/completion_service.proto
+++ b/google/cloud/retail/v2beta/completion_service.proto
@@ -36,8 +36,8 @@ option ruby_package = "Google::Cloud::Retail::V2beta";
 // Auto-completion service for retail.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Contact Retail Support (retail-search-support@google.com) if you are
-// interested in using Retail Search.
+// Please submit a form [here](https://cloud.google.com/contact) to contact
+// cloud sales if you are interested in using Retail Search.
 service CompletionService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -46,8 +46,8 @@ service CompletionService {
   // Completes the specified prefix with keyword suggestions.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc CompleteQuery(CompleteQueryRequest) returns (CompleteQueryResponse) {
     option (google.api.http) = {
       get: "/v2beta/{catalog=projects/*/locations/*/catalogs/*}:completeQuery"
@@ -59,8 +59,8 @@ service CompletionService {
   // Request processing may be synchronous. Partial updating is not supported.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc ImportCompletionData(ImportCompletionDataRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -135,13 +135,15 @@ message CompleteQueryRequest {
   // * user-data
   //
   // * cloud-retail
-  //   This option is not automatically enabled. Before using cloud-retail,
-  //   contact retail-search-support@google.com first.
+  //   This option requires additional allowlisting. Before using cloud-retail,
+  //   contact Cloud Retail support team first.
   string dataset = 6;
 
-  // Completion max suggestions.
+  // Completion max suggestions. If left unset or set to 0, then will fallback
+  // to the configured value [CompletionConfig.max_suggestions][].
   //
-  // The maximum allowed max suggestions is 20. The default value is 20.
+  // The maximum allowed max suggestions is 20. If it is set higher, it will be
+  // capped by 20.
   int32 max_suggestions = 5;
 }
 
@@ -172,9 +174,9 @@ message CompleteQueryResponse {
   // performance.
   string attribution_token = 2;
 
-  // Matched recent searches of this user. This field is a restricted feature.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in enabling it.
+  // Matched recent searches of this user. The maximum number of recent searches
+  // is 10. This field is a restricted feature. Contact Retail Search support
+  // team if you are interested in enabling it.
   //
   // This feature is only available when
   // [CompleteQueryRequest.visitor_id][google.cloud.retail.v2beta.CompleteQueryRequest.visitor_id]
diff --git a/google/cloud/retail/v2beta/import_config.proto b/google/cloud/retail/v2beta/import_config.proto
index bd8db707e..d9a2f2741 100644
--- a/google/cloud/retail/v2beta/import_config.proto
+++ b/google/cloud/retail/v2beta/import_config.proto
@@ -160,13 +160,13 @@ message ImportProductsRequest {
     // Can only be while using
     // [BigQuerySource][google.cloud.retail.v2beta.BigQuerySource].
     //
-    // Add the IAM permission “BigQuery Data Viewer” for
+    // Add the IAM permission "BigQuery Data Viewer" for
     // cloud-retail-customer-data-access@system.gserviceaccount.com before
     // using this feature otherwise an error is thrown.
     //
     // This feature is only available for users who have Retail Search enabled.
-    // Contact Retail Support (retail-search-support@google.com) if you are
-    // interested in using Retail Search.
+    // Please submit a form [here](https://cloud.google.com/contact) to contact
+    // cloud sales if you are interested in using Retail Search.
     FULL = 2;
   }
 
@@ -303,7 +303,7 @@ message CompletionDataInputConfig {
   oneof source {
     // Required. BigQuery input source.
     //
-    // Add the IAM permission “BigQuery Data Viewer” for
+    // Add the IAM permission "BigQuery Data Viewer" for
     // cloud-retail-customer-data-access@system.gserviceaccount.com before
     // using this feature otherwise an error is thrown.
     BigQuerySource big_query_source = 1
diff --git a/google/cloud/retail/v2beta/product.proto b/google/cloud/retail/v2beta/product.proto
index d729036bf..7a1331afb 100644
--- a/google/cloud/retail/v2beta/product.proto
+++ b/google/cloud/retail/v2beta/product.proto
@@ -315,13 +315,9 @@ message Product {
   // This field needs to pass all below criteria, otherwise an INVALID_ARGUMENT
   // error is returned:
   //
-  // * Max entries count: 200 by default; 100 for
-  // [Type.VARIANT][google.cloud.retail.v2beta.Product.Type.VARIANT].
+  // * Max entries count: 200.
   // * The key must be a UTF-8 encoded string with a length limit of 128
   //   characters.
-  // * Max indexable entries count: 200 by default; 40 for
-  // [Type.VARIANT][google.cloud.retail.v2beta.Product.Type.VARIANT].
-  // * Max searchable entries count: 30.
   // * For indexable attribute, the key must match the pattern:
   //   [a-zA-Z0-9][a-zA-Z0-9_]*. For example, key0LikeThis or KEY_1_LIKE_THIS.
   map<string, CustomAttribute> attributes = 12;
@@ -431,7 +427,7 @@ message Product {
 
   // The material of the product. For example, "leather", "wooden".
   //
-  // A maximum of 5 values are allowed. Each value must be a UTF-8 encoded
+  // A maximum of 20 values are allowed. Each value must be a UTF-8 encoded
   // string with a length limit of 128 characters. Otherwise, an
   // INVALID_ARGUMENT error is returned.
   //
@@ -532,8 +528,12 @@ message Product {
   // * [name][google.cloud.retail.v2beta.Product.name]
   // * [color_info][google.cloud.retail.v2beta.Product.color_info]
   //
-  // Maximum number of paths is 20. Otherwise, an INVALID_ARGUMENT error is
+  // Maximum number of paths is 30. Otherwise, an INVALID_ARGUMENT error is
   // returned.
+  //
+  // Note: Returning more fields in
+  // [SearchResponse][google.cloud.retail.v2beta.SearchResponse] may increase
+  // response payload size and serving latency.
   google.protobuf.FieldMask retrievable_fields = 30;
 
   // Output only. Product variants grouped together on primary product which
diff --git a/google/cloud/retail/v2beta/product_service.proto b/google/cloud/retail/v2beta/product_service.proto
index a8a1911f9..53937b4b6 100644
--- a/google/cloud/retail/v2beta/product_service.proto
+++ b/google/cloud/retail/v2beta/product_service.proto
@@ -145,8 +145,8 @@ service ProductService {
   // [RemoveFulfillmentPlaces][google.cloud.retail.v2beta.ProductService.RemoveFulfillmentPlaces].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc SetInventory(SetInventoryRequest) returns (google.longrunning.Operation) {
     option (google.api.http) = {
       post: "/v2beta/{inventory.name=projects/*/locations/*/catalogs/*/branches/*/products/**}:setInventory"
@@ -172,8 +172,8 @@ service ProductService {
   // [ListProducts][google.cloud.retail.v2beta.ProductService.ListProducts].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc AddFulfillmentPlaces(AddFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -200,8 +200,8 @@ service ProductService {
   // [ListProducts][google.cloud.retail.v2beta.ProductService.ListProducts].
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc RemoveFulfillmentPlaces(RemoveFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
diff --git a/google/cloud/retail/v2beta/search_service.proto b/google/cloud/retail/v2beta/search_service.proto
index 41f583605..764c0e6e0 100644
--- a/google/cloud/retail/v2beta/search_service.proto
+++ b/google/cloud/retail/v2beta/search_service.proto
@@ -39,8 +39,8 @@ option ruby_package = "Google::Cloud::Retail::V2beta";
 // Service for search.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Contact Retail Support (retail-search-support@google.com) if you are
-// interested in using Retail Search.
+// Please submit a form [here](https://cloud.google.com/contact) to contact
+// cloud sales if you are interested in using Retail Search.
 service SearchService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -49,8 +49,8 @@ service SearchService {
   // Performs a search.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Contact Retail Support (retail-search-support@google.com) if you are
-  // interested in using Retail Search.
+  // Please submit a form [here](https://cloud.google.com/contact) to contact
+  // cloud sales if you are interested in using Retail Search.
   rpc Search(SearchRequest) returns (SearchResponse) {
     option (google.api.http) = {
       post: "/v2beta/{placement=projects/*/locations/*/catalogs/*/placements/*}:search"
@@ -68,42 +68,42 @@ message SearchRequest {
     // Specifies how a facet is computed.
     message FacetKey {
       // Required. Supported textual and numerical facet keys in
-      // [Product][google.cloud.retail.v2beta.Product] object, over which the
-      // facet values are computed. Facet key is case-sensitive.
+      // [Product][google.cloud.retail.v2.Product] object, over which the facet
+      // values are computed. Facet key is case-sensitive.
       //
       // Allowed facet keys when
-      // [FacetKey.query][google.cloud.retail.v2beta.SearchRequest.FacetSpec.FacetKey.query]
+      // [FacetKey.query][google.cloud.retail.v2.SearchRequest.FacetSpec.FacetKey.query]
       // is not specified:
       //
-      // Textual facet keys:
-      // * brands
-      // * categories
-      // * genders
-      // * ageGroups
-      // * availability
-      // * colorFamilies
-      // * colors
-      // * sizes
-      // * materials
-      // * patterns
-      // * conditions
-      // * attributes.key
-      // * pickupInStore
-      // * shipToStore
-      // * sameDayDelivery
-      // * nextDayDelivery
-      // * customFulfillment1
-      // * customFulfillment2
-      // * customFulfillment3
-      // * customFulfillment4
-      // * customFulfillment5
+      // * textual_field =
+      //     * "brands"
+      //     * "categories"
+      //     * "genders"
+      //     * "ageGroups"
+      //     * "availability"
+      //     * "colorFamilies"
+      //     * "colors"
+      //     * "sizes"
+      //     * "materials"
+      //     * "patterns"
+      //     * "conditions"
+      //     * "attributes.key"
+      //     * "pickupInStore"
+      //     * "shipToStore"
+      //     * "sameDayDelivery"
+      //     * "nextDayDelivery"
+      //     * "customFulfillment1"
+      //     * "customFulfillment2"
+      //     * "customFulfillment3"
+      //     * "customFulfillment4"
+      //     * "customFulfillment5"
       //
-      // Numeric facet keys:
-      // * price
-      // * discount
-      // * rating
-      // * ratingCount
-      // * attributes.key
+      // * numerical_field =
+      //     * "price"
+      //     * "discount"
+      //     * "rating"
+      //     * "ratingCount"
+      //     * "attributes.key"
       string key = 1 [(google.api.field_behavior) = REQUIRED];
 
       // Set only if values should be bucketized into intervals. Must be set
@@ -167,7 +167,8 @@ message SearchRequest {
       // order](https://en.wikipedia.org/wiki/Natural_sort_order); numerical
       // intervals are sorted in the order given by
       // [FacetSpec.FacetKey.intervals][google.cloud.retail.v2beta.SearchRequest.FacetSpec.FacetKey.intervals];
-      // [FulfillmentInfo.ids][] are sorted in the order given by
+      // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+      // are sorted in the order given by
       // [FacetSpec.FacetKey.restricted_values][google.cloud.retail.v2beta.SearchRequest.FacetSpec.FacetKey.restricted_values].
       string order_by = 4;
 
@@ -289,12 +290,11 @@ message SearchRequest {
       // Examples:
       //
       // * To boost products with product ID "product_1" or "product_2", and
-      // color "Red" or "Blue":
-      //   ```
-      //   (id: ANY("product_1", "product_2"))
-      //   AND
-      //   (colorFamilies: ANY("Red", "Blue"))
-      //   ```
+      // color
+      //   "Red" or "Blue":<br>
+      //   *(id: ANY("product_1", "product_2"))<br>*
+      //   *AND<br>*
+      //   *(colorFamilies: ANY("Red", "Blue"))<br>*
       string condition = 1;
 
       // Strength of the condition boost, which should be in [-1, 1]. Negative
@@ -345,6 +345,11 @@ message SearchRequest {
     // The condition under which query expansion should occur. Default to
     // [Condition.DISABLED][google.cloud.retail.v2beta.SearchRequest.QueryExpansionSpec.Condition.DISABLED].
     Condition condition = 1;
+
+    // Whether to pin unexpanded results. If this field is set to true,
+    // unexpanded products are always at the top of the search results, followed
+    // by the expanded results.
+    bool pin_unexpanded_results = 2;
   }
 
   // Required. The resource name of the search engine placement, such as
@@ -411,7 +416,8 @@ message SearchRequest {
 
   // The filter syntax consists of an expression language for constructing a
   // predicate from one or more fields of the products being filtered. Filter
-  // expression is case-sensitive.
+  // expression is case-sensitive. See more details at this [user
+  // guide](/retail/private/docs/filter-and-order#filter).
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string filter = 10;
@@ -429,7 +435,9 @@ message SearchRequest {
 
   // The order in which products are returned. Products can be ordered by
   // a field in an [Product][google.cloud.retail.v2beta.Product] object. Leave
-  // it unset if ordered by relevance. OrderBy expression is case-sensitive.
+  // it unset if ordered by relevance. OrderBy expression is case-sensitive. See
+  // more details at this [user
+  // guide](/retail/private/docs/filter-and-order#order).
   //
   // If this field is unrecognizable, an INVALID_ARGUMENT is returned.
   string order_by = 11;
@@ -443,16 +451,17 @@ message SearchRequest {
   // The specification for dynamically generated facets. Notice that only
   // textual facets can be dynamically generated.
   //
-  // This feature requires additional allowlisting. Contact Retail Support
-  // (retail-search-support@google.com) if you are interested in using dynamic
-  // facet feature.
+  // This feature requires additional allowlisting. Contact Retail Search
+  // support team if you are interested in using dynamic facet feature.
   DynamicFacetSpec dynamic_facet_spec = 21;
 
-  // Boost specification to boost certain products.
+  // Boost specification to boost certain products. See more details at this
+  // [user guide](/retail/private/docs/boosting).
   BoostSpec boost_spec = 13;
 
   // The query expansion specification that specifies the conditions under which
-  // query expansion will occur.
+  // query expansion will occur. See more details at this [user
+  // guide](/retail/private/docs/result-size#query_expansion).
   QueryExpansionSpec query_expansion_spec = 14;
 
   // The keys to fetch and rollup the matching
@@ -466,10 +475,9 @@ message SearchRequest {
   // [Product][google.cloud.retail.v2beta.Product]s attributes will lead to
   // extra query latency. Maximum number of keys is 10.
   //
-  // For
-  // [Product.fulfillment_info][google.cloud.retail.v2beta.Product.fulfillment_info],
-  // a fulfillment type and a fulfillment ID must be provided in the format of
-  // "fulfillmentType.filfillmentId". E.g., in "pickupInStore.store123",
+  // For [FulfillmentInfo][google.cloud.retail.v2beta.FulfillmentInfo], a
+  // fulfillment type and a fulfillment ID must be provided in the format of
+  // "fulfillmentType.fulfillmentId". E.g., in "pickupInStore.store123",
   // "pickupInStore" is fulfillment type and "store123" is the store ID.
   //
   // Supported keys are:
@@ -480,24 +488,42 @@ message SearchRequest {
   // * discount
   // * attributes.key, where key is any key in the
   //   [Product.attributes][google.cloud.retail.v2beta.Product.attributes] map.
-  // * pickupInStore.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.PICKUP_IN_STORE][].
-  // * shipToStore.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.SHIP_TO_STORE][].
-  // * sameDayDelivery.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.SAME_DAY_DELIVERY][].
-  // * nextDayDelivery.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.NEXT_DAY_DELIVERY][].
-  // * customFulfillment1.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_1][].
-  // * customFulfillment2.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_2][].
-  // * customFulfillment3.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_3][].
-  // * customFulfillment4.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_4][].
-  // * customFulfillment5.id, where id is any [FulfillmentInfo.ids][] for type
-  //   [FulfillmentInfo.Type.CUSTOM_TYPE_5][].
+  // * pickupInStore.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "pickup-in-store".
+  // * shipToStore.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "ship-to-store".
+  // * sameDayDelivery.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "same-day-delivery".
+  // * nextDayDelivery.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "next-day-delivery".
+  // * customFulfillment1.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "custom-type-1".
+  // * customFulfillment2.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "custom-type-2".
+  // * customFulfillment3.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "custom-type-3".
+  // * customFulfillment4.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "custom-type-4".
+  // * customFulfillment5.id, where id is any
+  // [FulfillmentInfo.place_ids][google.cloud.retail.v2beta.FulfillmentInfo.place_ids]
+  // for [FulfillmentInfo.type][google.cloud.retail.v2beta.FulfillmentInfo.type]
+  //   "custom-type-5".
   //
   // If this field is set to an invalid value other than these, an
   // INVALID_ARGUMENT error is returned.
@@ -589,9 +615,8 @@ message SearchResponse {
     //       }
     //     }
     //
-    // For
-    // [Product.fulfillment_info][google.cloud.retail.v2beta.Product.fulfillment_info],
-    // the rollup values is a double value with type
+    // For [FulfillmentInfo][google.cloud.retail.v2beta.FulfillmentInfo], the
+    // rollup values is a double value with type
     // [google.protobuf.Value][google.protobuf.Value]. For example,
     // `{key: "pickupInStore.store1" value { number_value: 10 }}` means a there
     // are 10 variants in this product are available in the store "store1".
@@ -631,6 +656,11 @@ message SearchResponse {
   message QueryExpansionInfo {
     // Bool describing whether query expansion has occurred.
     bool expanded_query = 1;
+
+    // Number of pinned results. This field will only be set when expansion
+    // happens and [SearchRequest.query_expansion_spec.pin_unexpanded_results][]
+    // is set to true.
+    int64 pinned_result_count = 2;
   }
 
   // A list of matched items. The order represents the ranking.
diff --git a/google/cloud/retail/v2beta/user_event.proto b/google/cloud/retail/v2beta/user_event.proto
index f132eedcc..325b6e54e 100644
--- a/google/cloud/retail/v2beta/user_event.proto
+++ b/google/cloud/retail/v2beta/user_event.proto
@@ -259,9 +259,21 @@ message UserEvent {
 message ProductDetail {
   // Required. [Product][google.cloud.retail.v2beta.Product] information.
   //
-  // Only [Product.id][google.cloud.retail.v2beta.Product.id] field is used when
-  // ingesting an event, all other product fields are ignored as we will look
-  // them up from the catalog.
+  // Required field(s):
+  //
+  // * [Product.id][google.cloud.retail.v2beta.Product.id]
+  //
+  // Optional override field(s):
+  //
+  // * [Product.price_info][google.cloud.retail.v2beta.Product.price_info]
+  //
+  // If any supported optional fields are provided, we will treat them as a full
+  // override when looking up product information from the catalog. Thus, it is
+  // important to ensure that the overriding fields are accurate and
+  // complete.
+  //
+  // All other product fields are ignored and instead populated via catalog
+  // lookup after event ingestion.
   Product product = 1 [(google.api.field_behavior) = REQUIRED];
 
   // Quantity of the product associated with the user event.