diff --git a/google/cloud/retail/logging/error_log.proto b/google/cloud/retail/logging/error_log.proto
index 1286ea8458..b0944768d9 100644
--- a/google/cloud/retail/logging/error_log.proto
+++ b/google/cloud/retail/logging/error_log.proto
@@ -59,9 +59,9 @@ message ErrorContext {
   SourceLocation report_location = 2;
 }
 
-// The error payload that is populated on LRO import APIs. Including:
-//   "google.cloud.retail.v2.ProductService.ImportProducts"
-//   "google.cloud.retail.v2.EventService.ImportUserEvents"
+// The error payload that is populated on LRO import APIs, including
+//   "google.cloud.retail.v2.ProductService.ImportProducts" and
+//   "google.cloud.retail.v2.EventService.ImportUserEvents".
 message ImportErrorContext {
   // The operation resource name of the LRO.
   string operation_name = 1;
diff --git a/google/cloud/retail/v2alpha/catalog.proto b/google/cloud/retail/v2alpha/catalog.proto
index f6c114d7ca..95b7dd9443 100644
--- a/google/cloud/retail/v2alpha/catalog.proto
+++ b/google/cloud/retail/v2alpha/catalog.proto
@@ -104,8 +104,7 @@ message CatalogAttribute {
 
   // The status of the indexable option of a catalog attribute.
   enum IndexableOption {
-    // Value used when unset. Defaults to
-    // [INDEXABLE_ENABLED][google.cloud.retail.v2alpha.CatalogAttribute.IndexableOption.INDEXABLE_ENABLED].
+    // Value used when unset.
     INDEXABLE_OPTION_UNSPECIFIED = 0;
 
     // Indexable option enabled for an attribute.
@@ -117,8 +116,7 @@ message CatalogAttribute {
 
   // The status of the dynamic facetable option of a catalog attribute.
   enum DynamicFacetableOption {
-    // Value used when unset. Defaults to
-    // [DYNAMIC_FACETABLE_ENABLED][google.cloud.retail.v2alpha.CatalogAttribute.DynamicFacetableOption.DYNAMIC_FACETABLE_ENABLED].
+    // Value used when unset.
     DYNAMIC_FACETABLE_OPTION_UNSPECIFIED = 0;
 
     // Dynamic facetable option enabled for an attribute.
@@ -130,8 +128,7 @@ message CatalogAttribute {
 
   // The status of the searchable option of a catalog attribute.
   enum SearchableOption {
-    // Value used when unset. Defaults to
-    // [SEARCHABLE_DISABLED][google.cloud.retail.v2alpha.CatalogAttribute.SearchableOption.SEARCHABLE_DISABLED].
+    // Value used when unset.
     SEARCHABLE_OPTION_UNSPECIFIED = 0;
 
     // Searchable option enabled for an attribute.
@@ -141,6 +138,32 @@ message CatalogAttribute {
     SEARCHABLE_DISABLED = 2;
   }
 
+  // The status of the exact-searchable option of a catalog attribute.
+  enum ExactSearchableOption {
+    // Value used when unset. Defaults to
+    // [EXACT_SEARCHABLE_DISABLED][google.cloud.retail.v2alpha.CatalogAttribute.ExactSearchableOption.EXACT_SEARCHABLE_DISABLED].
+    EXACT_SEARCHABLE_OPTION_UNSPECIFIED = 0;
+
+    // Exact searchable option enabled for an attribute.
+    EXACT_SEARCHABLE_ENABLED = 1;
+
+    // Exact searchable option disabled for an attribute.
+    EXACT_SEARCHABLE_DISABLED = 2;
+  }
+
+  // The status of the retrievable option of a catalog attribute.
+  enum RetrievableOption {
+    // Value used when unset. Defaults to
+    // [RETRIEVABLE_DISABLED][google.cloud.retail.v2alpha.CatalogAttribute.RetrievableOption.RETRIEVABLE_DISABLED].
+    RETRIEVABLE_OPTION_UNSPECIFIED = 0;
+
+    // Retrievable option enabled for an attribute.
+    RETRIEVABLE_ENABLED = 1;
+
+    // Retrievable option disabled for an attribute.
+    RETRIEVABLE_DISABLED = 2;
+  }
+
   // Required. Attribute name.
   // For example: `color`, `brands`, `attributes.custom_attribute`, such as
   // `attributes.xyz`.
@@ -165,13 +188,13 @@ message CatalogAttribute {
   // APIs. This field is `False` for pre-loaded
   // [CatalogAttribute][google.cloud.retail.v2alpha.CatalogAttribute]s.
   //
-  // Only pre-loaded
-  // [CatalogAttribute][google.cloud.retail.v2alpha.CatalogAttribute]s that are
-  // neither in use by products nor predefined can be deleted.
-  // [CatalogAttribute][google.cloud.retail.v2alpha.CatalogAttribute]s that are
-  // either in use by products or are predefined cannot be deleted; however,
-  // their configuration properties will reset to default values upon removal
-  // request.
+  // Only pre-loaded [catalog
+  // attributes][google.cloud.retail.v2alpha.CatalogAttribute] that are neither
+  // in use by products nor predefined can be deleted. [Catalog
+  // attributes][google.cloud.retail.v2alpha.CatalogAttribute] that are
+  // either in use by products or are predefined attributes cannot be deleted;
+  // however, their configuration properties will reset to default values upon
+  // removal request.
   //
   // After catalog changes, it takes about 10 minutes for this field to update.
   bool in_use = 9 [(google.api.field_behavior) = OUTPUT_ONLY];
@@ -185,12 +208,16 @@ message CatalogAttribute {
   // is CATALOG_LEVEL_ATTRIBUTE_CONFIG, if INDEXABLE_ENABLED attribute values
   // are indexed so that it can be filtered, faceted, or boosted in
   // [SearchService.Search][google.cloud.retail.v2alpha.SearchService.Search].
+  //
+  // Must be specified, otherwise throws INVALID_FORMAT error.
   IndexableOption indexable_option = 5;
 
   // If DYNAMIC_FACETABLE_ENABLED, attribute values are available for dynamic
   // facet. Could only be DYNAMIC_FACETABLE_DISABLED if
   // [CatalogAttribute.indexable_option][google.cloud.retail.v2alpha.CatalogAttribute.indexable_option]
   // is INDEXABLE_DISABLED. Otherwise, an INVALID_ARGUMENT error is returned.
+  //
+  // Must be specified, otherwise throws INVALID_FORMAT error.
   DynamicFacetableOption dynamic_facetable_option = 6;
 
   // When
@@ -203,6 +230,8 @@ message CatalogAttribute {
   // will not be searchable by text queries in
   // [SearchService.Search][google.cloud.retail.v2alpha.SearchService.Search],
   // as there are no text values associated to numerical attributes.
+  //
+  // Must be specified, otherwise throws INVALID_FORMAT error.
   SearchableOption searchable_option = 7;
 
   // When
@@ -212,6 +241,15 @@ message CatalogAttribute {
   // This option works for categorical features only,
   // does not work for numerical features, inventory filtering.
   RecommendationsFilteringOption recommendations_filtering_option = 8;
+
+  // If EXACT_SEARCHABLE_ENABLED, attribute values will be exact searchable.
+  // This property only applies to textual custom attributes and requires
+  // indexable set to enabled to enable exact-searchable.
+  ExactSearchableOption exact_searchable_option = 11;
+
+  // If RETRIEVABLE_ENABLED, attribute values are retrievable in the search
+  // results.
+  RetrievableOption retrievable_option = 12;
 }
 
 // Catalog level attribute config.
@@ -336,21 +374,21 @@ message CompletionConfig {
 // will be streamed to the linked branch.
 message MerchantCenterLink {
   // Required. The linked [Merchant center account
-  // id](https://developers.google.com/shopping-content/guides/accountstatuses).
+  // ID](https://developers.google.com/shopping-content/guides/accountstatuses).
   // The account must be a standalone account or a sub-account of a MCA.
   int64 merchant_center_account_id = 1 [(google.api.field_behavior) = REQUIRED];
 
-  // The branch id (e.g. 0/1/2) within this catalog that products from
+  // The branch ID (e.g. 0/1/2) within this catalog that products from
   // merchant_center_account_id are streamed to. When updating this field, an
   // empty value will use the currently configured default branch. However,
   // changing the default branch later on won't change the linked branch here.
   //
-  // A single branch id can only have one linked merchant center account id.
+  // A single branch ID can only have one linked merchant center account ID.
   string branch_id = 2;
 
   // 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]
+  // List of possible values is given in [Included
+  // destination](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"
@@ -375,6 +413,21 @@ message MerchantCenterLink {
   //
   // Example value: `en`.
   string language_code = 5;
+
+  // Criteria for the Merchant Center feeds to be ingested via the link.
+  // All offers will be ingested if the list is empty.
+  // Otherwise the offers will be ingested from selected feeds.
+  repeated MerchantCenterFeedFilter feeds = 6;
+}
+
+// Merchant Center Feed filter criterion.
+message MerchantCenterFeedFilter {
+  // Merchant Center primary feed ID.
+  int64 primary_feed_id = 1;
+
+  // Merchant Center primary feed name. The name is used for the display
+  // purposes only.
+  string primary_feed_name = 2;
 }
 
 // Configures Merchant Center linking.
diff --git a/google/cloud/retail/v2alpha/catalog_service.proto b/google/cloud/retail/v2alpha/catalog_service.proto
index 088c01922d..d14a79a83c 100644
--- a/google/cloud/retail/v2alpha/catalog_service.proto
+++ b/google/cloud/retail/v2alpha/catalog_service.proto
@@ -186,6 +186,17 @@ service CatalogService {
     };
   }
 
+  // Removes all specified
+  // [CatalogAttribute][google.cloud.retail.v2alpha.CatalogAttribute]s from the
+  // [AttributesConfig][google.cloud.retail.v2alpha.AttributesConfig].
+  rpc BatchRemoveCatalogAttributes(BatchRemoveCatalogAttributesRequest)
+      returns (BatchRemoveCatalogAttributesResponse) {
+    option (google.api.http) = {
+      post: "/v2alpha/{attributes_config=projects/*/locations/*/catalogs/*/attributesConfig}:batchRemoveCatalogAttributes"
+      body: "*"
+    };
+  }
+
   // Replaces the specified
   // [CatalogAttribute][google.cloud.retail.v2alpha.CatalogAttribute] in the
   // [AttributesConfig][google.cloud.retail.v2alpha.AttributesConfig] by
@@ -341,7 +352,7 @@ message GetDefaultBranchResponse {
 // method.
 message GetCompletionConfigRequest {
   // Required. Full CompletionConfig resource name. Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/completionConfig
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/completionConfig`
   string name = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = {
@@ -449,6 +460,44 @@ message RemoveCatalogAttributeRequest {
   string key = 2 [(google.api.field_behavior) = REQUIRED];
 }
 
+// Request for
+// [CatalogService.BatchRemoveCatalogAttributes][google.cloud.retail.v2alpha.CatalogService.BatchRemoveCatalogAttributes]
+// method.
+message BatchRemoveCatalogAttributesRequest {
+  // Required. The attributes config resource shared by all catalog attributes
+  // being deleted. Format:
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/attributesConfig`
+  string attributes_config = 1 [
+    (google.api.field_behavior) = REQUIRED,
+    (google.api.resource_reference) = {
+      type: "retail.googleapis.com/AttributesConfig"
+    }
+  ];
+
+  // Required. The attribute name keys of the
+  // [CatalogAttribute][google.cloud.retail.v2alpha.CatalogAttribute]s to
+  // delete. A maximum of 1000 catalog attributes can be deleted in a batch.
+  repeated string attribute_keys = 2 [(google.api.field_behavior) = REQUIRED];
+}
+
+// Response of the
+// [CatalogService.BatchRemoveCatalogAttributes][google.cloud.retail.v2alpha.CatalogService.BatchRemoveCatalogAttributes].
+message BatchRemoveCatalogAttributesResponse {
+  // Catalog attributes that were deleted. Only pre-loaded [catalog
+  // attributes][google.cloud.retail.v2alpha.CatalogAttribute] that are
+  // neither [in
+  // use][google.cloud.retail.v2alpha.CatalogAttribute.in_use] by
+  // products nor predefined can be deleted.
+  repeated string deleted_catalog_attributes = 1;
+
+  // Catalog attributes that were reset. [Catalog
+  // attributes][google.cloud.retail.v2alpha.CatalogAttribute] that are either
+  // [in use][google.cloud.retail.v2alpha.CatalogAttribute.in_use] by products
+  // or are predefined attributes cannot be deleted; however, their
+  // configuration properties will reset to default values upon removal request.
+  repeated string reset_catalog_attributes = 2;
+}
+
 // Request for
 // [CatalogService.ReplaceCatalogAttribute][google.cloud.retail.v2alpha.CatalogService.ReplaceCatalogAttribute]
 // method.
diff --git a/google/cloud/retail/v2alpha/common.proto b/google/cloud/retail/v2alpha/common.proto
index 02cf05ba8e..4a06b4273e 100644
--- a/google/cloud/retail/v2alpha/common.proto
+++ b/google/cloud/retail/v2alpha/common.proto
@@ -72,7 +72,7 @@ enum RecommendationsFilteringOption {
 // The use case of Cloud Retail Search.
 enum SearchSolutionUseCase {
   // The value when it's unspecified. In this case, server behavior defaults to
-  // [SEARCH_SOLUTION_USE_CASE_SEARCH][].
+  // [SEARCH_SOLUTION_USE_CASE_SEARCH][google.cloud.retail.v2alpha.SearchSolutionUseCase.SEARCH_SOLUTION_USE_CASE_SEARCH].
   SEARCH_SOLUTION_USE_CASE_UNSPECIFIED = 0;
 
   // Search use case. Expects the traffic has a non-empty
@@ -97,8 +97,8 @@ message Condition {
     // Value cannot be empty.
     // Value can have at most 3 terms if specified as a partial match. Each
     // space separated string is considered as one term.
-    // Example) "a b c" is 3 terms and allowed, " a b c d" is 4 terms and not
-    // allowed for partial match.
+    // For example, "a b c" is 3 terms and allowed, but " a b c d" is 4 terms
+    // and not allowed for a partial match.
     string value = 1;
 
     // Whether this is supposed to be a full or partial match.
@@ -127,10 +127,12 @@ message Condition {
 }
 
 // A rule is a condition-action pair
+//
 // * A condition defines when a rule is to be triggered.
 // * An action specifies what occurs on that trigger.
-// Currently only boost rules are supported.
-// Currently only supported by the search endpoint.
+// Currently rules only work for [controls][google.cloud.retail.v2alpha.Control]
+// with
+// [SOLUTION_TYPE_SEARCH][google.cloud.retail.v2alpha.SolutionType.SOLUTION_TYPE_SEARCH].
 message Rule {
   // A boost action to apply to results matching condition specified above.
   message BoostAction {
@@ -216,7 +218,8 @@ message Rule {
   }
 
   // Creates a set of terms that will be treated as synonyms of each other.
-  // Example: synonyms of "sneakers" and "shoes".
+  // Example: synonyms of "sneakers" and "shoes":
+  //
   //  * "sneakers" will use a synonym of "shoes".
   //  * "shoes" will use a synonym of "sneakers".
   message TwowaySynonymsAction {
diff --git a/google/cloud/retail/v2alpha/completion_service.proto b/google/cloud/retail/v2alpha/completion_service.proto
index 9f399d2233..323bc05d60 100644
--- a/google/cloud/retail/v2alpha/completion_service.proto
+++ b/google/cloud/retail/v2alpha/completion_service.proto
@@ -36,7 +36,7 @@ option ruby_package = "Google::Cloud::Retail::V2alpha";
 // Auto-completion service for retail.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Please enable Retail Search on Cloud Console before using this feature.
+// Enable Retail Search on Cloud Console before using this feature.
 service CompletionService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -45,7 +45,7 @@ service CompletionService {
   // Completes the specified prefix with keyword suggestions.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc CompleteQuery(CompleteQueryRequest) returns (CompleteQueryResponse) {
     option (google.api.http) = {
       get: "/v2alpha/{catalog=projects/*/locations/*/catalogs/*}:completeQuery"
@@ -60,7 +60,7 @@ service CompletionService {
   // are indexed successfully and ready for serving. The process takes hours.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc ImportCompletionData(ImportCompletionDataRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -110,8 +110,10 @@ message CompleteQueryRequest {
   // number of language codes is 3.
   repeated string language_codes = 3;
 
-  // The device type context for completion suggestions.
-  // It is useful to apply different suggestions on different device types, e.g.
+  // The device type context for completion suggestions. We recommend that you
+  // leave this field empty.
+  //
+  // It can apply different suggestions on different device types, e.g.
   // `DESKTOP`, `MOBILE`. If it is empty, the suggestions are across all device
   // types.
   //
@@ -148,6 +150,11 @@ message CompleteQueryRequest {
   // The maximum allowed max suggestions is 20. If it is set higher, it will be
   // capped by 20.
   int32 max_suggestions = 5;
+
+  // If true, attribute suggestions are enabled and provided in response.
+  //
+  // This field is only available for "cloud-retail" dataset.
+  bool enable_attribute_suggestions = 9;
 }
 
 // Response of the auto-complete query.
@@ -175,6 +182,12 @@ message CompleteQueryResponse {
     string recent_search = 1;
   }
 
+  // Resource that represents attribute results.
+  message AttributeResult {
+    // The list of suggestions for the attribute.
+    repeated string suggestions = 1;
+  }
+
   // Results of the matching suggestions. The result list is ordered and the
   // first result is top suggestion.
   repeated CompletionResult completion_results = 1;
@@ -207,4 +220,14 @@ message CompleteQueryResponse {
   // Recent searches are deduplicated. More recent searches will be reserved
   // when duplication happens.
   repeated RecentSearchResult recent_search_results = 3;
+
+  // A map of matched attribute suggestions. This field is only available for
+  // "cloud-retail" dataset.
+  //
+  // Current supported keys:
+  //
+  // * `brands`
+  //
+  // * `categories`
+  map<string, AttributeResult> attribute_results = 4;
 }
diff --git a/google/cloud/retail/v2alpha/control.proto b/google/cloud/retail/v2alpha/control.proto
index cdd683d573..6ad604ea42 100644
--- a/google/cloud/retail/v2alpha/control.proto
+++ b/google/cloud/retail/v2alpha/control.proto
@@ -30,8 +30,9 @@ option objc_class_prefix = "RETAIL";
 option php_namespace = "Google\\Cloud\\Retail\\V2alpha";
 option ruby_package = "Google::Cloud::Retail::V2alpha";
 
-// Configures dynamic serving time metadata that is used to pre and post
-// process search/recommendation model results.
+// Configures dynamic metadata that can be linked to a
+// [ServingConfig][google.cloud.retail.v2alpha.ServingConfig] and affect search
+// or recommendation results at serving time.
 message Control {
   option (google.api.resource) = {
     type: "retail.googleapis.com/Control"
@@ -45,7 +46,10 @@ message Control {
   // INVALID_ARGUMENT will be returned if either condition is violated.
   oneof control {
     // A facet specification to perform faceted search.
-    SearchRequest.FacetSpec facet_spec = 3;
+    //
+    // Note that this field is deprecated and will throw NOT_IMPLEMENTED if
+    // used for creating a control.
+    SearchRequest.FacetSpec facet_spec = 3 [deprecated = true];
 
     // A rule control - a condition-action pair.
     // Enacts a set action when the condition is triggered.
@@ -63,30 +67,34 @@ message Control {
   // characters. Otherwise, an INVALID_ARGUMENT error is thrown.
   string display_name = 2 [(google.api.field_behavior) = REQUIRED];
 
-  // Output only. List of serving configuration ids that that are associated
-  // with this control. Note the association is managed via the ServingConfig,
-  // this is an output only denormalizeed  view. Assumed to be in the same
-  // catalog.
+  // Output only. List of [serving
+  // config][google.cloud.retail.v2alpha.ServingConfig] ids that are associated
+  // with this control in the same
+  // [Catalog][google.cloud.retail.v2alpha.Catalog].
+  //
+  // Note the association is managed via the
+  // [ServingConfig][google.cloud.retail.v2alpha.ServingConfig], this is an
+  // output only denormalized view.
   repeated string associated_serving_config_ids = 5
       [(google.api.field_behavior) = OUTPUT_ONLY];
 
-  // Required. Immutable. The solution types that the serving config is used
-  // for. Currently we support setting only one type of solution at creation
-  // time.
+  // Required. Immutable. The solution types that the control is used for.
+  // Currently we support setting only one type of solution at creation time.
   //
   // Only `SOLUTION_TYPE_SEARCH` value is supported at the moment.
   // If no solution type is provided at creation time, will default to
-  // SOLUTION_TYPE_SEARCH.
+  // [SOLUTION_TYPE_SEARCH][google.cloud.retail.v2alpha.SolutionType.SOLUTION_TYPE_SEARCH].
   repeated SolutionType solution_types = 6 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.field_behavior) = IMMUTABLE
   ];
 
-  // Required. Specifies the use case for the control.
+  // Specifies the use case for the control.
   // Affects what condition fields can be set.
   // Only settable by search controls.
-  // Will default to SEARCH_SOLUTION_USE_CASE_SEARCH if not specified.
-  // Currently only allow one search_solution_use_case per control.
-  repeated SearchSolutionUseCase search_solution_use_case = 7
-      [(google.api.field_behavior) = REQUIRED];
+  // Will default to
+  // [SEARCH_SOLUTION_USE_CASE_SEARCH][google.cloud.retail.v2alpha.SearchSolutionUseCase.SEARCH_SOLUTION_USE_CASE_SEARCH]
+  // if not specified. Currently only allow one search_solution_use_case per
+  // control.
+  repeated SearchSolutionUseCase search_solution_use_case = 7;
 }
diff --git a/google/cloud/retail/v2alpha/control_service.proto b/google/cloud/retail/v2alpha/control_service.proto
index d69201a3d1..53744cded2 100644
--- a/google/cloud/retail/v2alpha/control_service.proto
+++ b/google/cloud/retail/v2alpha/control_service.proto
@@ -66,7 +66,7 @@ service ControlService {
   //
   // [Control][google.cloud.retail.v2alpha.Control] cannot be set to a different
   // oneof field, if so an INVALID_ARGUMENT is returned. If the
-  // [Control][google.cloud.retail.v2alpha.Control] to delete does not exist, a
+  // [Control][google.cloud.retail.v2alpha.Control] to update does not exist, a
   // NOT_FOUND error is returned.
   rpc UpdateControl(UpdateControlRequest) returns (Control) {
     option (google.api.http) = {
@@ -84,7 +84,8 @@ service ControlService {
     option (google.api.method_signature) = "name";
   }
 
-  // Lists all Controls linked to this catalog.
+  // Lists all Controls by their parent
+  // [Catalog][google.cloud.retail.v2alpha.Catalog].
   rpc ListControls(ListControlsRequest) returns (ListControlsResponse) {
     option (google.api.http) = {
       get: "/v2alpha/{parent=projects/*/locations/*/catalogs/*}/controls"
@@ -140,7 +141,7 @@ message DeleteControlRequest {
 
 // Request for GetControl method.
 message GetControlRequest {
-  // Required. The resource name of the Control to delete. Format:
+  // Required. The resource name of the Control to get. Format:
   // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/controls/{control_id}`
   string name = 1 [
     (google.api.field_behavior) = REQUIRED,
diff --git a/google/cloud/retail/v2alpha/export_config.proto b/google/cloud/retail/v2alpha/export_config.proto
index dd907d1ea9..831bb2ec55 100644
--- a/google/cloud/retail/v2alpha/export_config.proto
+++ b/google/cloud/retail/v2alpha/export_config.proto
@@ -16,6 +16,8 @@ syntax = "proto3";
 
 package google.cloud.retail.v2alpha;
 
+import "google/api/field_behavior.proto";
+import "google/api/resource.proto";
 import "google/protobuf/timestamp.proto";
 import "google/rpc/status.proto";
 
@@ -40,7 +42,7 @@ message ExportErrorsConfig {
   }
 }
 
-// Metadata related to the progress of the Export operation. This will be
+// Metadata related to the progress of the Export operation. This is
 // returned by the google.longrunning.Operation.metadata field.
 message ExportMetadata {
   // Operation create time.
@@ -79,10 +81,14 @@ message ExportUserEventsResponse {
   OutputResult output_result = 3;
 }
 
-// Output result.
+// Output result that stores the information about where the exported data is
+// stored.
 message OutputResult {
-  // Export result in BigQuery.
+  // The BigQuery location where the result is stored.
   repeated BigQueryOutputResult bigquery_result = 1;
+
+  // The Google Cloud Storage location where the result is stored.
+  repeated GcsOutputResult gcs_result = 2;
 }
 
 // A BigQuery output result.
@@ -93,3 +99,9 @@ message BigQueryOutputResult {
   // The ID of a BigQuery Table.
   string table_id = 2;
 }
+
+// A Gcs output result.
+message GcsOutputResult {
+  // The uri of Gcs output
+  string output_uri = 1;
+}
diff --git a/google/cloud/retail/v2alpha/import_config.proto b/google/cloud/retail/v2alpha/import_config.proto
index 319edb1eac..8b7d87b956 100644
--- a/google/cloud/retail/v2alpha/import_config.proto
+++ b/google/cloud/retail/v2alpha/import_config.proto
@@ -35,7 +35,6 @@ option php_namespace = "Google\\Cloud\\Retail\\V2alpha";
 option ruby_package = "Google::Cloud::Retail::V2alpha";
 
 // Google Cloud Storage location for input content.
-// format.
 message GcsSource {
   // Required. Google Cloud Storage URIs to input files. URI can be up to
   // 2000 characters long. URIs can match the full object path (for example,
@@ -66,12 +65,12 @@ message GcsSource {
   //
   // Supported values for control imports:
   //
-  // * 'control' (default): One JSON
+  // * `control` (default): One JSON
   // [Control][google.cloud.retail.v2alpha.Control] per line.
   //
   // Supported values for catalog attribute imports:
   //
-  // * 'catalog_attribute' (default): One CSV
+  // * `catalog_attribute` (default): One CSV
   // [CatalogAttribute][google.cloud.retail.v2alpha.CatalogAttribute] per line.
   string data_schema = 2;
 }
@@ -83,9 +82,8 @@ message BigQuerySource {
   oneof partition {
     // BigQuery time partitioned table's _PARTITIONDATE in YYYY-MM-DD format.
     //
-    // Only supported when
-    // [ImportProductsRequest.reconciliation_mode][google.cloud.retail.v2alpha.ImportProductsRequest.reconciliation_mode]
-    // is set to `FULL`.
+    // Only supported in
+    // [ImportProductsRequest][google.cloud.retail.v2alpha.ImportProductsRequest].
     google.type.Date partition_date = 6;
   }
 
@@ -124,8 +122,7 @@ message BigQuerySource {
   // * `user_event_ga360`:
   //   The schema is available here:
   //   https://support.google.com/analytics/answer/3437719.
-  // * `user_event_ga4`: This feature is in private preview. Please contact the
-  //   support team for importing Google Analytics 4 events.
+  // * `user_event_ga4`:
   //   The schema is available here:
   //   https://support.google.com/analytics/answer/7029846.
   //
@@ -156,7 +153,7 @@ message ImportErrorsConfig {
   // Required. Errors destination.
   oneof destination {
     // Google Cloud Storage prefix for import errors. This must be an empty,
-    // existing Cloud Storage directory. Import errors will be written to
+    // existing Cloud Storage directory. Import errors are written to
     // sharded files in this directory, one per line, as a JSON-encoded
     // `google.rpc.Status` message.
     string gcs_prefix = 1;
@@ -176,16 +173,6 @@ message ImportProductsRequest {
 
     // Calculates diff and replaces the entire product dataset. Existing
     // products may be deleted if they are not present in the source location.
-    //
-    // Can only be set while using
-    // [BigQuerySource][google.cloud.retail.v2alpha.BigQuerySource]. And the
-    // BigQuery dataset must be created in the data location "us (multiple
-    // regions in United States)", otherwise a PERMISSION_DENIED error is
-    // thrown.
-    //
-    // 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.
     FULL = 2;
   }
 
@@ -208,8 +195,8 @@ message ImportProductsRequest {
   // The desired location of errors incurred during the Import.
   ImportErrorsConfig errors_config = 3;
 
-  // Indicates which fields in the provided imported 'products' to update. If
-  // not set, will by default update all fields.
+  // Indicates which fields in the provided imported `products` to update. If
+  // not set, all fields are updated.
   google.protobuf.FieldMask update_mask = 4;
 
   // The mode of reconciliation between existing products and the products to be
@@ -218,24 +205,19 @@ message ImportProductsRequest {
   ReconciliationMode reconciliation_mode = 5;
 
   // Full Pub/Sub topic name for receiving notification. If this field is set,
-  // when the import is finished, a notification will be sent to
-  // specified Pub/Sub topic. The message data will be JSON string of a
+  // when the import is finished, a notification is sent to
+  // specified Pub/Sub topic. The message data is JSON string of a
   // [Operation][google.longrunning.Operation].
   //
   // Format of the Pub/Sub topic is `projects/{project}/topics/{topic}`. It has
   // to be within the same project as
   // [ImportProductsRequest.parent][google.cloud.retail.v2alpha.ImportProductsRequest.parent].
-  // Make sure that both
-  // `cloud-retail-customer-data-access@system.gserviceaccount.com` and
-  // `service-<project number>@gcp-sa-retail.iam.gserviceaccount.com`
-  // have the `pubsub.topics.publish` IAM permission on the topic.
-  //
-  // Only supported when
-  // [ImportProductsRequest.reconciliation_mode][google.cloud.retail.v2alpha.ImportProductsRequest.reconciliation_mode]
-  // is set to `FULL`.
+  // Make sure that `service-<project
+  // number>@gcp-sa-retail.iam.gserviceaccount.com` has the
+  // `pubsub.topics.publish` IAM permission on the topic.
   string notification_pubsub_topic = 7;
 
-  // If true, will perform the FULL import even if it would delete a large
+  // If true, this performs the FULL import even if it would delete a large
   // proportion of the products in the default branch, which could potentially
   // cause outages if you have live predict/search traffic.
   //
@@ -277,8 +259,8 @@ message ImportCompletionDataRequest {
       [(google.api.field_behavior) = REQUIRED];
 
   // Pub/Sub topic for receiving notification. If this field is set,
-  // when the import is finished, a notification will be sent to
-  // specified Pub/Sub topic. The message data will be JSON string of a
+  // when the import is finished, a notification is sent to
+  // specified Pub/Sub topic. The message data is JSON string of a
   // [Operation][google.longrunning.Operation].
   // Format of the Pub/Sub topic is `projects/{project}/topics/{topic}`.
   string notification_pubsub_topic = 3;
@@ -338,7 +320,7 @@ message CompletionDataInputConfig {
   }
 }
 
-// Metadata related to the progress of the Import operation. This will be
+// Metadata related to the progress of the Import operation. This is
 // returned by the google.longrunning.Operation.metadata field.
 message ImportMetadata {
   // Operation create time.
@@ -358,11 +340,24 @@ message ImportMetadata {
   string request_id = 5 [deprecated = true];
 
   // Pub/Sub topic for receiving notification. If this field is set,
-  // when the import is finished, a notification will be sent to
-  // specified Pub/Sub topic. The message data will be JSON string of a
+  // when the import is finished, a notification is sent to
+  // specified Pub/Sub topic. The message data is JSON string of a
   // [Operation][google.longrunning.Operation].
   // Format of the Pub/Sub topic is `projects/{project}/topics/{topic}`.
   string notification_pubsub_topic = 6;
+
+  // Metadata related to transform user events.
+  TransformedUserEventsMetadata transformed_user_events_metadata = 7;
+}
+
+// Metadata related to transform user events operation.
+message TransformedUserEventsMetadata {
+  // Count of entries in the source user events BigQuery table.
+  int64 source_events_count = 1;
+
+  // Count of entries in the transformed user events BigQuery table, which could
+  // be different from the actually imported number of user events.
+  int64 transformed_events_count = 2;
 }
 
 // Response of the
diff --git a/google/cloud/retail/v2alpha/model.proto b/google/cloud/retail/v2alpha/model.proto
index 5f4ead9f7d..1b60792dbf 100644
--- a/google/cloud/retail/v2alpha/model.proto
+++ b/google/cloud/retail/v2alpha/model.proto
@@ -34,7 +34,7 @@ option ruby_package = "Google::Cloud::Retail::V2alpha";
 // [Model][google.cloud.retail.v2alpha.Model]. A
 // [Model][google.cloud.retail.v2alpha.Model] can be associated with a
 // [ServingConfig][google.cloud.retail.v2alpha.ServingConfig] and then queried
-// through the Predict api.
+// through the Predict API.
 message Model {
   option (google.api.resource) = {
     type: "retail.googleapis.com/Model"
@@ -44,7 +44,7 @@ message Model {
   // The PageOptimizationConfig for model training.
   //
   // This determines how many panels to optimize for, and which serving
-  // configurations to consider for each panel.
+  // configs to consider for each panel.
   // The purpose of this model is to optimize which
   // [ServingConfig][google.cloud.retail.v2alpha.ServingConfig] to show on which
   // panels in way that optimizes the visitors shopping journey.
@@ -56,9 +56,9 @@ message Model {
       oneof candidate {
         // This has to be a valid
         // [ServingConfig][google.cloud.retail.v2alpha.ServingConfig]
-        // identifier. e.g. for a ServingConfig with full name:
-        // `projects/*/locations/global/catalogs/default_catalog/servingConfigs/my_candidate_config`
-        // this would be 'my_candidate_config'
+        // identifier. For example, for a ServingConfig with full name:
+        // `projects/*/locations/global/catalogs/default_catalog/servingConfigs/my_candidate_config`,
+        // this would be `my_candidate_config`.
         string serving_config_id = 1;
       }
     }
@@ -71,13 +71,11 @@ message Model {
       string display_name = 1 [(google.api.field_behavior) = OPTIONAL];
 
       // Required. The candidates to consider on the panel.
-      //
-      // Limit = 10.
       repeated Candidate candidates = 2
           [(google.api.field_behavior) = REQUIRED];
 
-      // Required. The default candidate (in case the model fails at serving
-      // time, we can fall back to the default).
+      // Required. The default candidate. If the model fails at serving time,
+      // we fall back to the default.
       Candidate default_candidate = 3 [(google.api.field_behavior) = REQUIRED];
     }
 
@@ -127,7 +125,7 @@ message Model {
       // home_page_ctr_diversity_low,
       //    pdp_cvr_no_diversity </i>
       //
-      // `Restriction` = UNIQUE_SERVING_CONFIG_RESTRICTION
+      // `Restriction` = `UNIQUE_SERVING_CONFIG_RESTRICTION`
       //
       // `Valid combinations`:
       //
@@ -160,7 +158,7 @@ message Model {
       // home_page_ctr_diversity_low,
       //  pdp_cvr_no_diversity </i>
       //
-      // `Restriction` = UNIQUE_MODEL_RESTRICTION
+      // `Restriction` = `UNIQUE_MODEL_RESTRICTION`
       //
       // `Valid combinations`:
       //
@@ -192,7 +190,7 @@ message Model {
       // home_page_ctr_diversity_low,
       //  pdp_cvr_no_diversity </i>
       //
-      // `Restriction` = UNIQUE_MODEL_RESTRICTION
+      // `Restriction` = `UNIQUE_MODEL_RESTRICTION`
       //
       // `Valid combinations`:
       //
@@ -247,10 +245,10 @@ message Model {
   }
 
   // Represents an ordered combination of valid serving configs, which
-  // / may be used for PAGE_OPTIMIZATION recommendations.
+  // can be used for `PAGE_OPTIMIZATION` recommendations.
   message ServingConfigList {
     // Optional. A set of valid serving configs that may be used for
-    // PAGE_OPTIMIZATION.
+    // `PAGE_OPTIMIZATION`.
     repeated string serving_config_ids = 1
         [(google.api.field_behavior) = OPTIONAL];
   }
@@ -266,7 +264,7 @@ message Model {
     // The model is serving and can be queried.
     ACTIVE = 2;
 
-    // The model is trained on tuned hyperparameters, and can be
+    // The model is trained on tuned hyperparameters and can be
     // queried.
     TUNED = 3;
   }
@@ -285,26 +283,26 @@ message Model {
 
   // Describes whether periodic tuning is enabled for this model
   // or not. Periodic tuning is scheduled at most every three months. You can
-  // start a tuning process manually by using the ModelTune
+  // start a tuning process manually by using the `TuneModel`
   // method, which starts a tuning process immediately and resets the quarterly
   // schedule. Enabling or disabling periodic tuning does not affect any
   // current tuning processes.
   enum PeriodicTuningState {
-    // Unspecified default value - should never be explicitly set.
+    // Unspecified default value, should never be explicitly set.
     PERIODIC_TUNING_STATE_UNSPECIFIED = 0;
 
     // The model has periodic tuning disabled. Tuning
-    // can be reenabled by calling the EnableModelPeriodicTuning
-    // method or by calling the TuneModel method.
+    // can be reenabled by calling the `EnableModelPeriodicTuning`
+    // method or by calling the `TuneModel` method.
     PERIODIC_TUNING_DISABLED = 1;
 
     // The model cannot be tuned with periodic tuning OR the
-    // TuneModel method. Hide the options in customer UI and
+    // `TuneModel` method. Hide the options in customer UI and
     // reject any requests through the backend self serve API.
     ALL_TUNING_DISABLED = 3;
 
     // The model has periodic tuning enabled. Tuning
-    // can be disabled by calling the DisableModelPeriodicTuning
+    // can be disabled by calling the `DisableModelPeriodicTuning`
     // method.
     PERIODIC_TUNING_ENABLED = 2;
   }
@@ -312,7 +310,7 @@ message Model {
   // Describes whether this model have sufficient training data
   // to be continuously trained.
   enum DataState {
-    // Unspecified default value - should never be explicitly set.
+    // Unspecified default value, should never be explicitly set.
     DATA_STATE_UNSPECIFIED = 0;
 
     // The model has sufficient training data.
@@ -335,7 +333,7 @@ message Model {
   // Required. The fully qualified resource name of the model.
   //
   // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}`
   // catalog_id has char limit of 50.
   // recommendation_model_id has char limit of 40.
   string name = 1 [(google.api.field_behavior) = REQUIRED];
@@ -343,21 +341,21 @@ message Model {
   // Required. The display name of the model.
   //
   // Should be human readable, used to display Recommendation Models in the
-  // Retail Cloud Cosole Dashboard. UTF-8 encoded string with limit of 1024
+  // Retail Cloud Console Dashboard. UTF-8 encoded string with limit of 1024
   // characters.
   string display_name = 2 [(google.api.field_behavior) = REQUIRED];
 
   // Optional. The training state that the model is in (e.g.
-  // TRAINING or PAUSED).
+  // `TRAINING` or `PAUSED`).
   //
   // Since part of the cost of running the service
   // is frequency of training - this can be used to determine when to train
   // model in order to control cost. If not specified: the default value for
-  // CreateModel method is TRAINING. the default value for
-  // UpdateModel method is to keep the state the same as before.
+  // `CreateModel` method is `TRAINING`. The default value for
+  // `UpdateModel` method is to keep the state the same as before.
   TrainingState training_state = 3 [(google.api.field_behavior) = OPTIONAL];
 
-  // Output only. The serving state of the model: ACTIVE, NOT_ACTIVE.
+  // Output only. The serving state of the model: `ACTIVE`, `NOT_ACTIVE`.
   ServingState serving_state = 4 [(google.api.field_behavior) = OUTPUT_ONLY];
 
   // Output only. Timestamp the Recommendation Model was created at.
@@ -373,8 +371,19 @@ message Model {
   // Required. The type of model e.g. `home-page`.
   //
   // Currently supported values: `recommended-for-you`, `others-you-may-like`,
-  // `frequently-bought-together`, `page-optimization`, 'similar-items',
-  // 'buy-it-again', `recently-viewed`(readonly value).
+  // `frequently-bought-together`, `page-optimization`, `similar-items`,
+  // `buy-it-again`, `on-sale-items`, and `recently-viewed`(readonly value).
+  //
+  //
+  // This field together with
+  // [optimization_objective][google.cloud.retail.v2alpha.Model.optimization_objective]
+  // describe model metadata to use to control model training and serving.
+  // See https://cloud.google.com/retail/docs/models
+  // for more details on what the model metadata control and which combination
+  // of parameters are valid. For invalid combinations of parameters (e.g. type
+  // = `frequently-bought-together` and optimization_objective = `ctr`), you
+  // receive an error 400 if you try to create/update a recommendation with
+  // this set of knobs.
   string type = 7 [(google.api.field_behavior) = REQUIRED];
 
   // Optional. The optimization objective e.g. `cvr`.
@@ -390,13 +399,23 @@ message Model {
   // `others-you-may-like` => `ctr`
   //
   // `frequently-bought-together` => `revenue_per_order`
+  //
+  // This field together with
+  // [optimization_objective][google.cloud.retail.v2alpha.Model.type]
+  // describe model metadata to use to control model training and serving.
+  // See https://cloud.google.com/retail/docs/models
+  // for more details on what the model metadata control and which combination
+  // of parameters are valid. For invalid combinations of parameters (e.g. type
+  // = `frequently-bought-together` and optimization_objective = `ctr`), you
+  // receive an error 400 if you try to create/update a recommendation with
+  // this set of knobs.
   string optimization_objective = 8 [(google.api.field_behavior) = OPTIONAL];
 
   // Optional. The state of periodic tuning.
   //
   // The period we use is 3 months - to do a
-  // one-off tune earlier use the TuneModel method. Default value
-  // is PERIODIC_TUNING_ENABLED.
+  // one-off tune earlier use the `TuneModel` method. Default value
+  // is `PERIODIC_TUNING_ENABLED`.
   PeriodicTuningState periodic_tuning_state = 11
       [(google.api.field_behavior) = OPTIONAL];
 
@@ -410,18 +429,18 @@ message Model {
   // recommendation. Empty field implies no tune is goig on.
   string tuning_operation = 15 [(google.api.field_behavior) = OUTPUT_ONLY];
 
-  // Output only. The state of data requirements for this model: DATA_OK and
-  // DATA_ERROR.
+  // Output only. The state of data requirements for this model: `DATA_OK` and
+  // `DATA_ERROR`.
   //
   // Recommendation model cannot be trained if the data is in
-  // DATA_ERROR state. Recommendation model can have DATA_ERROR state even if
-  // serving state is ACTIVE: models were trained successfully before, but
+  // `DATA_ERROR` state. Recommendation model can have `DATA_ERROR` state even
+  // if serving state is `ACTIVE`: models were trained successfully before, but
   // cannot be refreshed because model no longer has sufficient
   // data for training.
   DataState data_state = 16 [(google.api.field_behavior) = OUTPUT_ONLY];
 
-  // Optional. If RECOMMENDATIONS_FILTERING_ENABLED, recommendation filtering by
-  // attributes is enabled for the model.
+  // Optional. If `RECOMMENDATIONS_FILTERING_ENABLED`, recommendation filtering
+  // by attributes is enabled for the model.
   RecommendationsFilteringOption filtering_option = 18
       [(google.api.field_behavior) = OPTIONAL];
 
diff --git a/google/cloud/retail/v2alpha/model_service.proto b/google/cloud/retail/v2alpha/model_service.proto
index 30690f538f..af057c5142 100644
--- a/google/cloud/retail/v2alpha/model_service.proto
+++ b/google/cloud/retail/v2alpha/model_service.proto
@@ -36,11 +36,11 @@ option ruby_package = "Google::Cloud::Retail::V2alpha";
 
 // Service for performing CRUD operations on models.
 // Recommendation models contain all the metadata necessary to generate a set of
-// models for the Predict() api. A model is queried
+// models for the `Predict()` API. A model is queried
 // indirectly via a ServingConfig, which associates a model with a
 // given Placement (e.g. Frequently Bought Together on Home Page).
 //
-// This service allows customers to e.g.:
+// This service allows you to do the following:
 //
 // * Initiate training of a model.
 // * Pause training of an existing model.
@@ -59,8 +59,8 @@ service ModelService {
     };
     option (google.api.method_signature) = "parent,model";
     option (google.longrunning.operation_info) = {
-      response_type: "Model"
-      metadata_type: "CreateModelMetadata"
+      response_type: "google.cloud.retail.v2alpha.Model"
+      metadata_type: "google.cloud.retail.v2alpha.CreateModelMetadata"
     };
   }
 
@@ -99,8 +99,9 @@ service ModelService {
   }
 
   // Update of model metadata. Only fields that
-  // currently can be updated are: filtering_option, periodic_tuning_state.
-  // If other values are provided, this API method will ignore them.
+  // currently can be updated are: `filtering_option` and
+  // `periodic_tuning_state`.
+  // If other values are provided, this API method ignores them.
   rpc UpdateModel(UpdateModelRequest) returns (Model) {
     option (google.api.http) = {
       patch: "/v2alpha/{model.name=projects/*/locations/*/catalogs/*/models/*}"
@@ -117,8 +118,8 @@ service ModelService {
     };
     option (google.api.method_signature) = "name";
     option (google.longrunning.operation_info) = {
-      response_type: "TuneModelResponse"
-      metadata_type: "TuneModelMetadata"
+      response_type: "google.cloud.retail.v2alpha.TuneModelResponse"
+      metadata_type: "google.cloud.retail.v2alpha.TuneModelMetadata"
     };
   }
 }
@@ -126,27 +127,29 @@ service ModelService {
 // Request for creating a model.
 message CreateModelRequest {
   // Required. The parent resource under which to create the model. Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}`
   string parent = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = { type: "retail.googleapis.com/Catalog" }
   ];
 
-  // Required. The payload of the [Model]  to create.
+  // Required. The payload of the [Model][google.cloud.retail.v2alpha.Model]  to
+  // create.
   Model model = 2 [(google.api.field_behavior) = REQUIRED];
 
-  // Optional. Whether to run a dry_run to validate the request (without
+  // Optional. Whether to run a dry run to validate the request (without
   // actually creating the model).
   bool dry_run = 3 [(google.api.field_behavior) = OPTIONAL];
 }
 
 // Request for updating an existing model.
 message UpdateModelRequest {
-  // Required. The body of the updated [Model].
+  // Required. The body of the updated
+  // [Model][google.cloud.retail.v2alpha.Model].
   Model model = 1 [(google.api.field_behavior) = REQUIRED];
 
   // Optional. Indicates which fields in the provided 'model' to
-  // update. If not set, will by default update all fields.
+  // update. If not set, by default updates all fields.
   google.protobuf.FieldMask update_mask = 2
       [(google.api.field_behavior) = OPTIONAL];
 }
@@ -155,7 +158,7 @@ message UpdateModelRequest {
 message PauseModelRequest {
   // Required. The name of the model to pause.
   // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}`
   string name = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = { type: "retail.googleapis.com/Model" }
@@ -166,7 +169,7 @@ message PauseModelRequest {
 message ResumeModelRequest {
   // Required. The name of the model to resume.
   // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}`
   string name = 1 [(google.api.field_behavior) = REQUIRED];
 }
 
@@ -174,7 +177,7 @@ message ResumeModelRequest {
 message ListModelsRequest {
   // Required. The parent for which to list models.
   // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}`
   string parent = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = { type: "retail.googleapis.com/Catalog" }
@@ -191,9 +194,9 @@ message ListModelsRequest {
 
 // Request for deleting a model.
 message DeleteModelRequest {
-  // Required. The resource name of the [Model] to delete.
-  // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}
+  // Required. The resource name of the
+  // [Model][google.cloud.retail.v2alpha.Model] to delete. Format:
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}`
   string name = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = { type: "retail.googleapis.com/Model" }
@@ -214,7 +217,7 @@ message ListModelsResponse {
 message TuneModelRequest {
   // Required. The resource name of the model to tune.
   // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}`
   string name = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = { type: "retail.googleapis.com/Model" }
@@ -225,7 +228,7 @@ message TuneModelRequest {
 message CreateModelMetadata {
   // The resource name of the model that this create applies to.
   // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}`
   string model = 1;
 }
 
@@ -233,7 +236,7 @@ message CreateModelMetadata {
 message TuneModelMetadata {
   // The resource name of the model that this tune applies to.
   // Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/models/{model_id}`
   string model = 1;
 }
 
diff --git a/google/cloud/retail/v2alpha/prediction_service.proto b/google/cloud/retail/v2alpha/prediction_service.proto
index b76aed50b1..b88e97e7a3 100644
--- a/google/cloud/retail/v2alpha/prediction_service.proto
+++ b/google/cloud/retail/v2alpha/prediction_service.proto
@@ -19,6 +19,7 @@ package google.cloud.retail.v2alpha;
 import "google/api/annotations.proto";
 import "google/api/client.proto";
 import "google/api/field_behavior.proto";
+import "google/api/resource.proto";
 import "google/cloud/retail/v2alpha/user_event.proto";
 import "google/protobuf/struct.proto";
 
@@ -61,7 +62,7 @@ message PredictRequest {
   // The ID of the Recommendations AI serving config or placement.
   // Before you can request predictions from your model, you must create at
   // least one serving config or placement for it. For more information, see
-  // [Managing serving configurations]
+  // [Manage serving configs]
   // (https://cloud.google.com/retail/docs/manage-configs).
   //
   // The full list of available serving configs can be seen at
@@ -84,13 +85,13 @@ message PredictRequest {
   // [UserInfo.user_id][google.cloud.retail.v2alpha.UserInfo.user_id] unset.
   UserEvent user_event = 2 [(google.api.field_behavior) = REQUIRED];
 
-  // Maximum number of results to return per page. Set this property
-  // to the number of prediction results needed. If zero, the service will
-  // choose a reasonable default. The maximum allowed value is 100. Values
-  // above 100 will be coerced to 100.
+  // Maximum number of results to return. Set this property to the number of
+  // prediction results needed. If zero, the service will choose a reasonable
+  // default. The maximum allowed value is 100. Values above 100 will be coerced
+  // to 100.
   int32 page_size = 3;
 
-  // This field is not used for now; leave it unset.
+  // This field is not used; leave it unset.
   string page_token = 4 [deprecated = true];
 
   // Filter for restricting prediction results with a length limit of 5,000
@@ -116,12 +117,11 @@ message PredictRequest {
   //  * filterOutOfStockItems  tag=(-"promotional")
   //  * filterOutOfStockItems
   //
-  // If your filter blocks all prediction results, the API will return generic
-  // (unfiltered) popular products. If you only want results strictly matching
-  // the filters, set `strictFiltering` to True in `PredictRequest.params` to
-  // receive empty results instead.
-  // Note that the API will never return items with storageStatus of "EXPIRED"
-  // or "DELETED" regardless of filter choices.
+  // If your filter blocks all prediction results, the API will return *no*
+  // results. If instead you want empty result sets to return generic
+  // (unfiltered) popular products, set `strictFiltering` to False in
+  // `PredictRequest.params`. Note that the API will never return items with
+  // storageStatus of "EXPIRED" or "DELETED" regardless of filter choices.
   //
   // If `filterSyntaxV2` is set to true under the `params` field, then
   // attribute-based expressions are expected instead of the above described
@@ -148,7 +148,7 @@ message PredictRequest {
   // * `returnScore`: Boolean. If set to true, the prediction 'score'
   //    corresponding to each returned product will be set in the
   //    `results.metadata` field in the prediction response. The given
-  //    'score' indicates the probability of an product being clicked/purchased
+  //    'score' indicates the probability of a product being clicked/purchased
   //    given the user's context and history.
   // * `strictFiltering`: Boolean. True by default. If set to false, the service
   //    will return generic (unfiltered) popular products instead of empty if
diff --git a/google/cloud/retail/v2alpha/product.proto b/google/cloud/retail/v2alpha/product.proto
index f4826f1bdd..7dd20a744b 100644
--- a/google/cloud/retail/v2alpha/product.proto
+++ b/google/cloud/retail/v2alpha/product.proto
@@ -105,6 +105,13 @@ message Product {
   oneof expiration {
     // The timestamp when this product becomes unavailable for
     // [SearchService.Search][google.cloud.retail.v2alpha.SearchService.Search].
+    // Note that this is only applicable to
+    // [Type.PRIMARY][google.cloud.retail.v2alpha.Product.Type.PRIMARY] and
+    // [Type.COLLECTION][google.cloud.retail.v2alpha.Product.Type.COLLECTION],
+    // and ignored for
+    // [Type.VARIANT][google.cloud.retail.v2alpha.Product.Type.VARIANT]. In
+    // general, we suggest the users to delete the stale products explicitly,
+    // instead of using this field to determine staleness.
     //
     // If it is set, the [Product][google.cloud.retail.v2alpha.Product] is not
     // available for
@@ -125,7 +132,14 @@ message Product {
     // [expiration_date](https://support.google.com/merchants/answer/6324499).
     google.protobuf.Timestamp expire_time = 16;
 
-    // Input only. The TTL (time to live) of the product.
+    // Input only. The TTL (time to live) of the product. Note that this is only
+    // applicable to
+    // [Type.PRIMARY][google.cloud.retail.v2alpha.Product.Type.PRIMARY] and
+    // [Type.COLLECTION][google.cloud.retail.v2alpha.Product.Type.COLLECTION],
+    // and ignored for
+    // [Type.VARIANT][google.cloud.retail.v2alpha.Product.Type.VARIANT]. In
+    // general, we suggest the users to delete the stale products explicitly,
+    // instead of using this field to determine staleness.
     //
     // If it is set, it must be a non-negative value, and
     // [expire_time][google.cloud.retail.v2alpha.Product.expire_time] is set as
@@ -200,7 +214,7 @@ message Product {
   // The [type][google.cloud.retail.v2alpha.Product.type] of the members must be
   // either [Type.PRIMARY][google.cloud.retail.v2alpha.Product.Type.PRIMARY] or
   // [Type.VARIANT][google.cloud.retail.v2alpha.Product.Type.VARIANT] otherwise
-  // and INVALID_ARGUMENT error is thrown. Should not set it for other types. A
+  // an INVALID_ARGUMENT error is thrown. Should not set it for other types. A
   // maximum of 1000 values are allowed. Otherwise, an INVALID_ARGUMENT error is
   // return.
   repeated string collection_member_ids = 5;
@@ -231,7 +245,7 @@ message Product {
   //
   //
   // To represent full path of category, use '>' sign to separate different
-  // hierarchies. If '>' is part of the category name, please replace it with
+  // hierarchies. If '>' is part of the category name, replace it with
   // other character(s).
   //
   // For example, if a shoes product belongs to both
@@ -364,6 +378,11 @@ message Product {
   // The timestamp when this [Product][google.cloud.retail.v2alpha.Product]
   // becomes available for
   // [SearchService.Search][google.cloud.retail.v2alpha.SearchService.Search].
+  // Note that this is only applicable to
+  // [Type.PRIMARY][google.cloud.retail.v2alpha.Product.Type.PRIMARY] and
+  // [Type.COLLECTION][google.cloud.retail.v2alpha.Product.Type.COLLECTION], and
+  // ignored for
+  // [Type.VARIANT][google.cloud.retail.v2alpha.Product.Type.VARIANT].
   google.protobuf.Timestamp available_time = 18;
 
   // The online availability of the
@@ -551,7 +570,9 @@ message Product {
   // Note: Returning more fields in
   // [SearchResponse][google.cloud.retail.v2alpha.SearchResponse] can increase
   // response payload size and serving latency.
-  google.protobuf.FieldMask retrievable_fields = 30;
+  //
+  // This field is deprecated. Use the retrievable site-wide control instead.
+  google.protobuf.FieldMask retrievable_fields = 30 [deprecated = true];
 
   // Output only. Product variants grouped together on primary product which
   // share similar product attributes. It's automatically grouped by
@@ -564,4 +585,15 @@ message Product {
   // [ProductService.GetProduct][google.cloud.retail.v2alpha.ProductService.GetProduct].
   // Do not set this field in API requests.
   repeated Product variants = 31 [(google.api.field_behavior) = OUTPUT_ONLY];
+
+  // Output only. A list of local inventories specific to different places.
+  //
+  // This is only available for users who have Retail Search enabled, and it can
+  // be managed by
+  // [ProductService.AddLocalInventories][google.cloud.retail.v2alpha.ProductService.AddLocalInventories]
+  // and
+  // [ProductService.RemoveLocalInventories][google.cloud.retail.v2alpha.ProductService.RemoveLocalInventories]
+  // APIs.
+  repeated LocalInventory local_inventories = 35
+      [(google.api.field_behavior) = OUTPUT_ONLY];
 }
diff --git a/google/cloud/retail/v2alpha/product_service.proto b/google/cloud/retail/v2alpha/product_service.proto
index 1a5f702bb0..ec82c437f4 100644
--- a/google/cloud/retail/v2alpha/product_service.proto
+++ b/google/cloud/retail/v2alpha/product_service.proto
@@ -141,9 +141,9 @@ service ProductService {
   //
   // This process is asynchronous and does not require the
   // [Product][google.cloud.retail.v2alpha.Product] to exist before updating
-  // fulfillment information. If the request is valid, the update will be
-  // enqueued and processed downstream. As a consequence, when a response is
-  // returned, updates are not immediately manifested in the
+  // fulfillment information. If the request is valid, the update is enqueued
+  // and processed downstream. As a consequence, when a response is returned,
+  // updates are not immediately manifested in the
   // [Product][google.cloud.retail.v2alpha.Product] queried by
   // [ProductService.GetProduct][google.cloud.retail.v2alpha.ProductService.GetProduct]
   // or
@@ -153,10 +153,10 @@ service ProductService {
   // [ProductService.CreateProduct][google.cloud.retail.v2alpha.ProductService.CreateProduct]
   // and
   // [ProductService.UpdateProduct][google.cloud.retail.v2alpha.ProductService.UpdateProduct],
-  // the specified inventory field value(s) will overwrite any existing value(s)
+  // the specified inventory field value(s) overwrite any existing value(s)
   // while ignoring the last update time for this field. Furthermore, the last
-  // update time for the specified inventory fields will be overwritten to the
-  // time of the
+  // update times for the specified inventory fields are overwritten by the
+  // times of the
   // [ProductService.CreateProduct][google.cloud.retail.v2alpha.ProductService.CreateProduct]
   // or
   // [ProductService.UpdateProduct][google.cloud.retail.v2alpha.ProductService.UpdateProduct]
@@ -164,11 +164,11 @@ service ProductService {
   //
   // If no inventory fields are set in
   // [CreateProductRequest.product][google.cloud.retail.v2alpha.CreateProductRequest.product],
-  // then any pre-existing inventory information for this product will be used.
+  // then any pre-existing inventory information for this product is used.
   //
   // If no inventory fields are set in
   // [SetInventoryRequest.set_mask][google.cloud.retail.v2alpha.SetInventoryRequest.set_mask],
-  // then any existing inventory information will be preserved.
+  // then any existing inventory information is preserved.
   //
   // Pre-existing inventory information can only be updated with
   // [ProductService.SetInventory][google.cloud.retail.v2alpha.ProductService.SetInventory],
@@ -176,8 +176,17 @@ service ProductService {
   // and
   // [ProductService.RemoveFulfillmentPlaces][google.cloud.retail.v2alpha.ProductService.RemoveFulfillmentPlaces].
   //
+  // The returned [Operation][google.longrunning.Operation]s is obsolete after
+  // one day, and the [GetOperation][google.longrunning.Operations.GetOperation]
+  // API returns `NOT_FOUND` afterwards.
+  //
+  // If conflicting updates are issued, the
+  // [Operation][google.longrunning.Operation]s associated with the stale
+  // updates are not marked as [done][google.longrunning.Operation.done] until
+  // they are obsolete.
+  //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc SetInventory(SetInventoryRequest) returns (google.longrunning.Operation) {
     option (google.api.http) = {
       post: "/v2alpha/{inventory.name=projects/*/locations/*/catalogs/*/branches/*/products/**}:setInventory"
@@ -203,8 +212,17 @@ service ProductService {
   // or
   // [ProductService.ListProducts][google.cloud.retail.v2alpha.ProductService.ListProducts].
   //
+  // The returned [Operation][google.longrunning.Operation]s will be obsolete
+  // after 1 day, and [GetOperation][google.longrunning.Operations.GetOperation]
+  // API will return NOT_FOUND afterwards.
+  //
+  // If conflicting updates are issued, the
+  // [Operation][google.longrunning.Operation]s associated with the stale
+  // updates will not be marked as [done][google.longrunning.Operation.done]
+  // until being obsolete.
+  //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc AddFulfillmentPlaces(AddFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -231,8 +249,17 @@ service ProductService {
   // or
   // [ProductService.ListProducts][google.cloud.retail.v2alpha.ProductService.ListProducts].
   //
+  // The returned [Operation][google.longrunning.Operation]s will be obsolete
+  // after 1 day, and [GetOperation][google.longrunning.Operations.GetOperation]
+  // API will return NOT_FOUND afterwards.
+  //
+  // If conflicting updates are issued, the
+  // [Operation][google.longrunning.Operation]s associated with the stale
+  // updates will not be marked as [done][google.longrunning.Operation.done]
+  // until being obsolete.
+  //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc RemoveFulfillmentPlaces(RemoveFulfillmentPlacesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -266,8 +293,17 @@ service ProductService {
   // [ProductService.UpdateProduct][google.cloud.retail.v2alpha.ProductService.UpdateProduct]
   // has no effect on local inventories.
   //
+  // The returned [Operation][google.longrunning.Operation]s will be obsolete
+  // after 1 day, and [GetOperation][google.longrunning.Operations.GetOperation]
+  // API will return NOT_FOUND afterwards.
+  //
+  // If conflicting updates are issued, the
+  // [Operation][google.longrunning.Operation]s associated with the stale
+  // updates will not be marked as [done][google.longrunning.Operation.done]
+  // until being obsolete.
+  //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc AddLocalInventories(AddLocalInventoriesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -299,8 +335,17 @@ service ProductService {
   // [ProductService.UpdateProduct][google.cloud.retail.v2alpha.ProductService.UpdateProduct]
   // has no effect on local inventories.
   //
+  // The returned [Operation][google.longrunning.Operation]s will be obsolete
+  // after 1 day, and [GetOperation][google.longrunning.Operations.GetOperation]
+  // API will return NOT_FOUND afterwards.
+  //
+  // If conflicting updates are issued, the
+  // [Operation][google.longrunning.Operation]s associated with the stale
+  // updates will not be marked as [done][google.longrunning.Operation.done]
+  // until being obsolete.
+  //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc RemoveLocalInventories(RemoveLocalInventoriesRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
diff --git a/google/cloud/retail/v2alpha/retail_v2alpha.yaml b/google/cloud/retail/v2alpha/retail_v2alpha.yaml
index 65d5b6a58a..8955dd1bc4 100644
--- a/google/cloud/retail/v2alpha/retail_v2alpha.yaml
+++ b/google/cloud/retail/v2alpha/retail_v2alpha.yaml
@@ -64,12 +64,16 @@ backend:
   rules:
   - selector: google.cloud.retail.v2alpha.CatalogService.UpdateCatalog
     deadline: 10.0
+  - selector: google.cloud.retail.v2alpha.CompletionService.ImportCompletionData
+    deadline: 300.0
   - selector: 'google.cloud.retail.v2alpha.ModelService.*'
     deadline: 60.0
   - selector: 'google.cloud.retail.v2alpha.ProductService.*'
     deadline: 30.0
   - selector: google.cloud.retail.v2alpha.ProductService.ImportProducts
     deadline: 300.0
+  - selector: google.cloud.retail.v2alpha.UserEventService.CollectUserEvent
+    deadline: 10.0
   - selector: google.cloud.retail.v2alpha.UserEventService.ImportUserEvents
     deadline: 600.0
   - selector: google.cloud.retail.v2alpha.UserEventService.PurgeUserEvents
@@ -82,6 +86,7 @@ http:
   - selector: google.longrunning.Operations.GetOperation
     get: '/v2alpha/{name=projects/*/locations/*/catalogs/*/branches/*/operations/*}'
     additional_bindings:
+    - get: '/v2alpha/{name=projects/*/locations/*/catalogs/*/branches/*/places/*/operations/*}'
     - get: '/v2alpha/{name=projects/*/locations/*/catalogs/*/operations/*}'
     - get: '/v2alpha/{name=projects/*/locations/*/operations/*}'
     - get: '/v2alpha/{name=projects/*/operations/*}'
diff --git a/google/cloud/retail/v2alpha/search_service.proto b/google/cloud/retail/v2alpha/search_service.proto
index 24bfa34aac..37526c1f75 100644
--- a/google/cloud/retail/v2alpha/search_service.proto
+++ b/google/cloud/retail/v2alpha/search_service.proto
@@ -37,7 +37,7 @@ option ruby_package = "Google::Cloud::Retail::V2alpha";
 // Service for search.
 //
 // This feature is only available for users who have Retail Search enabled.
-// Please enable Retail Search on Cloud Console before using this feature.
+// Enable Retail Search on Cloud Console before using this feature.
 service SearchService {
   option (google.api.default_host) = "retail.googleapis.com";
   option (google.api.oauth_scopes) =
@@ -46,7 +46,7 @@ service SearchService {
   // Performs a search.
   //
   // This feature is only available for users who have Retail Search enabled.
-  // Please enable Retail Search on Cloud Console before using this feature.
+  // Enable Retail Search on Cloud Console before using this feature.
   rpc Search(SearchRequest) returns (SearchResponse) {
     option (google.api.http) = {
       post: "/v2alpha/{placement=projects/*/locations/*/catalogs/*/placements/*}:search"
@@ -218,7 +218,7 @@ message SearchRequest {
     FacetKey facet_key = 1 [(google.api.field_behavior) = REQUIRED];
 
     // Maximum of facet values that should be returned for this facet. If
-    // unspecified, defaults to 20. The maximum allowed value is 300. Values
+    // unspecified, defaults to 50. The maximum allowed value is 300. Values
     // above 300 will be coerced to 300.
     //
     // If this field is negative, an INVALID_ARGUMENT is returned.
@@ -396,7 +396,8 @@ message SearchRequest {
       // [Mode.AUTO][google.cloud.retail.v2alpha.SearchRequest.PersonalizationSpec.Mode.AUTO].
       MODE_UNSPECIFIED = 0;
 
-      // Let CRS decide whether to use personalization.
+      // Let CRS decide whether to use personalization based on quality of user
+      // event data.
       AUTO = 1;
 
       // Disable personalization.
@@ -458,15 +459,21 @@ message SearchRequest {
   // The search mode of each search request.
   enum SearchMode {
     // Default value. In this case both product search and faceted search will
-    // be performed. Both [SearchResponse.SearchResult] and
-    // [SearchResponse.Facet] will be returned.
+    // be performed. Both
+    // [SearchResponse.SearchResult][google.cloud.retail.v2alpha.SearchResponse.SearchResult]
+    // and
+    // [SearchResponse.Facet][google.cloud.retail.v2alpha.SearchResponse.Facet]
+    // will be returned.
     SEARCH_MODE_UNSPECIFIED = 0;
 
     // Only product search will be performed. The faceted search will be
     // disabled.
     //
-    // Only [SearchResponse.SearchResult] will be returned.
-    // [SearchResponse.Facet] will not be returned, even if
+    // Only
+    // [SearchResponse.SearchResult][google.cloud.retail.v2alpha.SearchResponse.SearchResult]
+    // will be returned.
+    // [SearchResponse.Facet][google.cloud.retail.v2alpha.SearchResponse.Facet]
+    // will not be returned, even if
     // [SearchRequest.facet_specs][google.cloud.retail.v2alpha.SearchRequest.facet_specs]
     // or
     // [SearchRequest.dynamic_facet_spec][google.cloud.retail.v2alpha.SearchRequest.dynamic_facet_spec]
@@ -481,7 +488,9 @@ message SearchRequest {
     // and
     // [SearchRequest.dynamic_facet_spec][google.cloud.retail.v2alpha.SearchRequest.dynamic_facet_spec]
     // should be set. Otherwise, an INVALID_ARGUMENT error is returned. Only
-    // [SearchResponse.Facet] will be returned. [SearchResponse.SearchResult]
+    // [SearchResponse.Facet][google.cloud.retail.v2alpha.SearchResponse.Facet]
+    // will be returned.
+    // [SearchResponse.SearchResult][google.cloud.retail.v2alpha.SearchResponse.SearchResult]
     // will not be returned.
     FACETED_SEARCH_ONLY = 2;
   }
@@ -490,7 +499,7 @@ message SearchRequest {
   // `projects/*/locations/global/catalogs/default_catalog/servingConfigs/default_serving_config`
   // or the name of the legacy placement resource, such as
   // `projects/*/locations/global/catalogs/default_catalog/placements/default_search`.
-  // This field is used to identify the serving configuration name and the set
+  // This field is used to identify the serving config name and the set
   // of models that will be used to make the search.
   string placement = 1 [(google.api.field_behavior) = REQUIRED];
 
@@ -713,7 +722,7 @@ message SearchRequest {
   // [UserEvent.page_categories][google.cloud.retail.v2alpha.UserEvent.page_categories];
   //
   // To represent full path of category, use '>' sign to separate different
-  // hierarchies. If '>' is part of the category name, please replace it with
+  // hierarchies. If '>' is part of the category name, replace it with
   // other character(s).
   //
   // Category pages include special pages such as sales or promotions. For
@@ -726,6 +735,15 @@ message SearchRequest {
   SearchMode search_mode = 31;
 
   // The specification for personalization.
+  //
+  // Notice that if both
+  // [ServingConfig.personalization_spec][google.cloud.retail.v2alpha.ServingConfig.personalization_spec]
+  // and
+  // [SearchRequest.personalization_spec][google.cloud.retail.v2alpha.SearchRequest.personalization_spec]
+  // are set.
+  // [SearchRequest.personalization_spec][google.cloud.retail.v2alpha.SearchRequest.personalization_spec]
+  // will override
+  // [ServingConfig.personalization_spec][google.cloud.retail.v2alpha.ServingConfig.personalization_spec].
   PersonalizationSpec personalization_spec = 32;
 
   // The labels applied to a resource must meet the following requirements:
@@ -829,6 +847,21 @@ message SearchResponse {
     // `{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;
+
+    // Specifies previous events related to this product for this user based on
+    // [UserEvent][google.cloud.retail.v2alpha.UserEvent] with same
+    // [SearchRequest.visitor_id][google.cloud.retail.v2alpha.SearchRequest.visitor_id]
+    // or [UserInfo.user_id][google.cloud.retail.v2alpha.UserInfo.user_id].
+    //
+    // This is set only when
+    // [SearchRequest.PersonalizationSpec.mode][google.cloud.retail.v2alpha.SearchRequest.PersonalizationSpec.mode]
+    // is
+    // [SearchRequest.PersonalizationSpec.Mode.AUTO][google.cloud.retail.v2alpha.SearchRequest.PersonalizationSpec.Mode.AUTO].
+    //
+    // Possible values:
+    //
+    // * `purchased`: Indicates that this product has been purchased before.
+    repeated string personal_labels = 7;
   }
 
   // A facet result.
diff --git a/google/cloud/retail/v2alpha/serving_config.proto b/google/cloud/retail/v2alpha/serving_config.proto
index d052401245..d4d02c70c4 100644
--- a/google/cloud/retail/v2alpha/serving_config.proto
+++ b/google/cloud/retail/v2alpha/serving_config.proto
@@ -32,14 +32,25 @@ option ruby_package = "Google::Cloud::Retail::V2alpha";
 
 // Configures metadata that is used to generate serving time results (e.g.
 // search results or recommendation predictions).
-// The ServingConfig is passed in the search and predict request and together
-// with the Catalog.default_branch, generates results.
 message ServingConfig {
   option (google.api.resource) = {
     type: "retail.googleapis.com/ServingConfig"
     pattern: "projects/{project}/locations/{location}/catalogs/{catalog}/servingConfigs/{serving_config}"
   };
 
+  // What type of diversity - data or rule based.
+  // If none is specified, default to rule based.
+  enum DiversityType {
+    // Default value.
+    DIVERSITY_TYPE_UNSPECIFIED = 0;
+
+    // Rule based diversity.
+    RULE_BASED_DIVERSITY = 2;
+
+    // Data driven diversity.
+    DATA_DRIVEN_DIVERSITY = 3;
+  }
+
   // Immutable. Fully qualified name
   // `projects/*/locations/global/catalogs/*/servingConfig/*`
   string name = 1 [(google.api.field_behavior) = IMMUTABLE];
@@ -51,7 +62,8 @@ message ServingConfig {
   // characters. Otherwise, an INVALID_ARGUMENT error is returned.
   string display_name = 2 [(google.api.field_behavior) = REQUIRED];
 
-  // The id of the model to use at serving time.
+  // The id of the model in the same
+  // [Catalog][google.cloud.retail.v2alpha.Catalog] to use at serving time.
   // Currently only RecommendationModels are supported:
   // https://cloud.google.com/retail/recommendations-ai/docs/create-models
   // Can be changed but only to a compatible model (e.g.
@@ -70,13 +82,13 @@ message ServingConfig {
   // click-through and conversion rates.
   //  Allowed values are:
   //
-  // * 'no-price-reranking'
-  // * 'low-price-raranking'
-  // * 'medium-price-reranking'
-  // * 'high-price-reranking'
+  // * `no-price-reranking`
+  // * `low-price-raranking`
+  // * `medium-price-reranking`
+  // * `high-price-reranking`
   //
   // If not specified, we choose default based on model type. Default value:
-  // 'no-price-reranking'.
+  // `no-price-reranking`.
   //
   // Can only be set if
   // [solution_types][google.cloud.retail.v2alpha.ServingConfig.solution_types]
@@ -205,16 +217,16 @@ message ServingConfig {
   repeated string ignore_control_ids = 15;
 
   // How much diversity to use in recommendation model results e.g.
-  // 'medium-diversity' or 'high-diversity'. Currently supported values:
+  // `medium-diversity` or `high-diversity`. Currently supported values:
   //
-  // * 'no-diversity'
-  // * 'low-diversity'
-  // * 'medium-diversity'
-  // * 'high-diversity'
-  // * 'auto-diversity'
+  // * `no-diversity`
+  // * `low-diversity`
+  // * `medium-diversity`
+  // * `high-diversity`
+  // * `auto-diversity`
   //
   // If not specified, we choose default based on recommendation model
-  // type. Default value: 'no-diversity'.
+  // type. Default value: `no-diversity`.
   //
   // Can only be set if
   // [solution_types][google.cloud.retail.v2alpha.ServingConfig.solution_types]
@@ -222,13 +234,16 @@ message ServingConfig {
   // [SOLUTION_TYPE_RECOMMENDATION][google.cloud.retail.v2main.SolutionType.SOLUTION_TYPE_RECOMMENDATION].
   string diversity_level = 8;
 
-  // Whether to add additional category filters on the 'similar-items' model.
+  // What kind of diversity to use - data driven or rule based.
+  DiversityType diversity_type = 20;
+
+  // Whether to add additional category filters on the `similar-items` model.
   // If not specified, we enable it by default.
   //  Allowed values are:
   //
-  // * 'no-category-match': No additional filtering of original results from
+  // * `no-category-match`: No additional filtering of original results from
   //   the model and the customer's filters.
-  // * 'relaxed-category-match': Only keep results with categories that match
+  // * `relaxed-category-match`: Only keep results with categories that match
   //   at least one item categories in the PredictRequests's context item.
   //   * If customer also sends filters in the PredictRequest, then the results
   //   will satisfy both conditions (user given and category match).
@@ -239,6 +254,23 @@ message ServingConfig {
   // [SOLUTION_TYPE_RECOMMENDATION][google.cloud.retail.v2main.SolutionType.SOLUTION_TYPE_RECOMMENDATION].
   string enable_category_filter_level = 16;
 
+  // The specification for personalization spec.
+  //
+  // Can only be set if
+  // [solution_types][google.cloud.retail.v2alpha.ServingConfig.solution_types]
+  // is
+  // [SOLUTION_TYPE_SEARCH][google.cloud.retail.v2main.SolutionType.SOLUTION_TYPE_SEARCH].
+  //
+  // Notice that if both
+  // [ServingConfig.personalization_spec][google.cloud.retail.v2alpha.ServingConfig.personalization_spec]
+  // and
+  // [SearchRequest.personalization_spec][google.cloud.retail.v2alpha.SearchRequest.personalization_spec]
+  // are set.
+  // [SearchRequest.personalization_spec][google.cloud.retail.v2alpha.SearchRequest.personalization_spec]
+  // will override
+  // [ServingConfig.personalization_spec][google.cloud.retail.v2alpha.ServingConfig.personalization_spec].
+  SearchRequest.PersonalizationSpec personalization_spec = 21;
+
   // Required. Immutable. Specifies the solution types that a serving config can
   // be associated with. Currently we support setting only one type of solution.
   repeated SolutionType solution_types = 19 [
diff --git a/google/cloud/retail/v2alpha/serving_config_service.proto b/google/cloud/retail/v2alpha/serving_config_service.proto
index 311126510e..387091079c 100644
--- a/google/cloud/retail/v2alpha/serving_config_service.proto
+++ b/google/cloud/retail/v2alpha/serving_config_service.proto
@@ -159,7 +159,7 @@ message UpdateServingConfigRequest {
 // Request for DeleteServingConfig method.
 message DeleteServingConfigRequest {
   // Required. The resource name of the ServingConfig to delete. Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}`
   string name = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = {
@@ -171,7 +171,7 @@ message DeleteServingConfigRequest {
 // Request for GetServingConfig method.
 message GetServingConfigRequest {
   // Required. The resource name of the ServingConfig to get. Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}`
   string name = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = {
@@ -183,7 +183,7 @@ message GetServingConfigRequest {
 // Request for ListServingConfigs method.
 message ListServingConfigsRequest {
   // Required. The catalog resource name. Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}`
   string parent = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = { type: "retail.googleapis.com/Catalog" }
@@ -211,7 +211,7 @@ message ListServingConfigsResponse {
 // Request for AddControl method.
 message AddControlRequest {
   // Required. The source ServingConfig resource name . Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}`
   string serving_config = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = {
@@ -227,7 +227,7 @@ message AddControlRequest {
 // Request for RemoveControl method.
 message RemoveControlRequest {
   // Required. The source ServingConfig resource name . Format:
-  // projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}
+  // `projects/{project_number}/locations/{location_id}/catalogs/{catalog_id}/servingConfigs/{serving_config_id}`
   string serving_config = 1 [
     (google.api.field_behavior) = REQUIRED,
     (google.api.resource_reference) = {
diff --git a/google/cloud/retail/v2alpha/user_event.proto b/google/cloud/retail/v2alpha/user_event.proto
index ca25f3003f..6d24ca2448 100644
--- a/google/cloud/retail/v2alpha/user_event.proto
+++ b/google/cloud/retail/v2alpha/user_event.proto
@@ -229,7 +229,7 @@ message UserEvent {
   // The categories associated with a category page.
   //
   // To represent full path of category, use '>' sign to separate different
-  // hierarchies. If '>' is part of the category name, please replace it with
+  // hierarchies. If '>' is part of the category name, replace it with
   // other character(s).
   //
   // Category pages include special pages such as sales or promotions. For
diff --git a/google/cloud/retail/v2alpha/user_event_service.proto b/google/cloud/retail/v2alpha/user_event_service.proto
index 35fe33f4ba..5e0702bca5 100644
--- a/google/cloud/retail/v2alpha/user_event_service.proto
+++ b/google/cloud/retail/v2alpha/user_event_service.proto
@@ -20,6 +20,7 @@ import "google/api/annotations.proto";
 import "google/api/client.proto";
 import "google/api/field_behavior.proto";
 import "google/api/httpbody.proto";
+import "google/api/resource.proto";
 import "google/cloud/retail/v2alpha/import_config.proto";
 import "google/cloud/retail/v2alpha/purge_config.proto";
 import "google/cloud/retail/v2alpha/user_event.proto";
@@ -79,9 +80,9 @@ service UserEventService {
   // synchronous. Events that already exist are skipped.
   // Use this method for backfilling historical user events.
   //
-  // Operation.response is of type ImportResponse. Note that it is
+  // `Operation.response` is of type `ImportResponse`. Note that it is
   // possible for a subset of the items to be successfully inserted.
-  // Operation.metadata is of type ImportMetadata.
+  // `Operation.metadata` is of type `ImportMetadata`.
   rpc ImportUserEvents(ImportUserEventsRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -94,14 +95,14 @@ service UserEventService {
     };
   }
 
-  // Starts a user event rejoin operation with latest product catalog. Events
-  // will not be annotated with detailed product information if product is
-  // missing from the catalog at the time the user event is ingested, and these
-  // events are stored as unjoined events with a limited usage on training and
-  // serving. This method can be used to start a join operation on specified
-  // events with latest version of product catalog. It can also be used to
-  // correct events joined with the wrong product catalog. A rejoin operation
-  // can take hours or days to complete.
+  // Starts a user-event rejoin operation with latest product catalog. Events
+  // are not annotated with detailed product information for products that are
+  // missing from the catalog when the user event is ingested. These
+  // events are stored as unjoined events with limited usage on training and
+  // serving. You can use this method to start a join operation on specified
+  // events with the latest version of product catalog. You can also use this
+  // method to correct events joined with the wrong product catalog. A rejoin
+  // operation can take hours or days to complete.
   rpc RejoinUserEvents(RejoinUserEventsRequest)
       returns (google.longrunning.Operation) {
     option (google.api.http) = {
@@ -123,10 +124,24 @@ message WriteUserEventRequest {
 
   // Required. User event to write.
   UserEvent user_event = 2 [(google.api.field_behavior) = REQUIRED];
+
+  // If set to true, the user event will be written asynchronously after
+  // validation, and the API will respond without waiting for the write.
+  // Therefore, silent failures can occur even if the API returns success. In
+  // case of silent failures, error messages can be found in Stackdriver logs.
+  bool write_async = 3;
 }
 
 // Request message for CollectUserEvent method.
 message CollectUserEventRequest {
+  // The rule that can convert the raw_json to a user event. It is needed
+  // only when the raw_json is set.
+  oneof conversion_rule {
+    // The prebuilt rule name that can convert a specific type of raw_json.
+    // For example: "default_schema/v1.0"
+    string prebuilt_rule = 6;
+  }
+
   // Required. The parent catalog name, such as
   // `projects/1234/locations/global/catalogs/default_catalog`.
   string parent = 1 [(google.api.field_behavior) = REQUIRED];
@@ -145,17 +160,23 @@ message CollectUserEventRequest {
   // otherwise identical get requests. The name is abbreviated to reduce the
   // payload bytes.
   int64 ets = 4;
+
+  // An arbitrary serialized JSON string that contains necessary information
+  // that can comprise a user event. When this field is specified, the
+  // user_event field will be ignored. Note: line-delimited JSON is not
+  // supported, a single JSON only.
+  string raw_json = 5;
 }
 
 // Request message for RejoinUserEvents method.
 message RejoinUserEventsRequest {
   // The scope of user events to be rejoined with the latest product catalog.
   // If the rejoining aims at reducing number of unjoined events, set
-  // UserEventRejoinScope to UNJOINED_EVENTS.
+  // `UserEventRejoinScope` to `UNJOINED_EVENTS`.
   // If the rejoining aims at correcting product catalog information in joined
-  // events, set UserEventRejoinScope to JOINED_EVENTS.
-  // If all events needs to be rejoined, set UserEventRejoinScope to
-  // USER_EVENT_REJOIN_SCOPE_UNSPECIFIED.
+  // events, set `UserEventRejoinScope` to `JOINED_EVENTS`.
+  // If all events needs to be rejoined, set `UserEventRejoinScope` to
+  // `USER_EVENT_REJOIN_SCOPE_UNSPECIFIED`.
   enum UserEventRejoinScope {
     // Rejoin all events with the latest product catalog, including both joined
     // events and unjoined events.
@@ -174,16 +195,16 @@ message RejoinUserEventsRequest {
 
   // The type of the user event rejoin to define the scope and range of the user
   // events to be rejoined with the latest product catalog. Defaults to
-  // USER_EVENT_REJOIN_SCOPE_UNSPECIFIED if this field is not set, or set to an
-  // invalid integer value.
+  // `USER_EVENT_REJOIN_SCOPE_UNSPECIFIED` if this field is not set, or set to
+  // an invalid integer value.
   UserEventRejoinScope user_event_rejoin_scope = 2;
 }
 
-// Response message for RejoinUserEvents method.
+// Response message for `RejoinUserEvents` method.
 message RejoinUserEventsResponse {
   // Number of user events that were joined with latest product catalog.
   int64 rejoined_user_events_count = 1;
 }
 
-// Metadata for RejoinUserEvents method.
+// Metadata for `RejoinUserEvents` method.
 message RejoinUserEventsMetadata {}