search: remove search-hybrid flag (#57507)

In our last release (5.1) we actually made this feature flag unused, but
did not remove the final references to it. Additionally we add a
CHANGELOG entry for the removal to the 5.1 section. This is quite a
minor change, so I don't think its worth calling out even though 5.1 has
already been released.

Test Plan: CI

Author: keegancsmith

CHANGELOG.md

@@ -80,6 +80,7 @@ All notable changes to Sourcegraph are documented in this file.
 - indexed-search has removed the deprecated environment variable ZOEKT_ENABLE_LAZY_DOC_SECTIONS [zoekt#620](https://github.com/sourcegraph/zoekt/pull/620)
 - The federation feature that could redirect users from their own Sourcegraph instance to public repositories on Sourcegraph.com has been removed. It allowed users to open a repository URL on their own Sourcegraph instance and, if the repository wasn't found on that instance, the user would be redirect to the repository on Sourcegraph.com, where it was possibly found. The feature has been broken for over a year though and we don't know that it was used. If you want to use it, please open a feature-request issue and tag the `@sourcegraph/source` team. [#55161](https://github.com/sourcegraph/sourcegraph/pull/55161)
 - The `applySearchQuerySuggestionOnEnter` experimental feature flag in user settings was removed, and this behavior is now always enabled. Previously, this behavior was on by default, but it was possible to disable it.
+- The feature-flag `search-hybrid`, which allowed to disable the performance improvements for unindexed search in 4.3, is now deprecated and will not be read anymore. [#56470](https://github.com/sourcegraph/sourcegraph/pull/56470)
 
 ## 5.1.9
 

cmd/searcher/protocol/searcher.go

@@ -52,13 +52,6 @@ type Request struct {
 	// Whether the revision to be searched is indexed or unindexed. This matters for
 	// structural search because it will query Zoekt for indexed structural search.
 	Indexed bool
-
-	// NOTE: This field is no longer read. It is always assumed to be true.
-	//
-	// FeatHybrid is a feature flag which enables hybrid search. Hybrid search
-	// will only search what has changed since Zoekt has indexed as well as
-	// including Zoekt results.
-	FeatHybrid bool `json:"feat_hybrid,omitempty"`
 }
 
 // PatternInfo describes a search request on a repo. Most of the fields
@@ -205,7 +198,6 @@ func (r *Request) ToProto() *proto.SearchRequest {
 			Select:                       r.PatternInfo.Select,
 		},
 		FetchTimeout: durationpb.New(r.FetchTimeout),
-		FeatHybrid:   r.FeatHybrid,
 	}
 }
 
@@ -235,7 +227,6 @@ func (r *Request) FromProto(req *proto.SearchRequest) {
 		},
 		FetchTimeout: req.FetchTimeout.AsDuration(),
 		Indexed:      req.Indexed,
-		FeatHybrid:   req.FeatHybrid,
 	}
 }
 

internal/search/client/client.go

@@ -295,7 +295,6 @@ func ToFeatures(flagSet *featureflag.FlagSet, logger log.Logger) *search.Feature
 
 	return &search.Features{
 		ContentBasedLangFilters: flagSet.GetBoolOr("search-content-based-lang-detection", false),
-		HybridSearch:            flagSet.GetBoolOr("search-hybrid", true), // can remove flag in 4.5
 		Debug:                   flagSet.GetBoolOr("search-debug", false),
 	}
 }

internal/search/searcher/client.go

@@ -71,7 +71,6 @@ func Search(
 		},
 		Indexed:      indexed,
 		FetchTimeout: fetchTimeout,
-		FeatHybrid:   features.HybridSearch, // TODO(keegan) HACK because I didn't want to change the signatures to so many function calls.
 	}
 
 	body, err := json.Marshal(r)

internal/search/searcher/client_grpc.go

@@ -60,7 +60,6 @@ func SearchGRPC(
 		},
 		Indexed:      indexed,
 		FetchTimeout: fetchTimeout,
-		FeatHybrid:   features.HybridSearch, // TODO(keegan) HACK because I didn't want to change the signatures to so many function calls.
 	}).ToProto()
 
 	// Searcher caches the file contents for repo@commit since it is

internal/search/types.go

@@ -416,11 +416,6 @@ type Features struct {
 	// currently just supported by Zoekt.
 	ContentBasedLangFilters bool `json:"search-content-based-lang-detection"`
 
-	// HybridSearch when true will consult the Zoekt index when running
-	// unindexed searches. Searcher (unindexed search) will the only search
-	// what has changed since the indexed commit.
-	HybridSearch bool `json:"search-hybrid"`
-
 	// Debug when true will set the Debug field on FileMatches. This may grow
 	// from here. For now we treat this like a feature flag for convenience.
 	Debug bool `json:"debug"`

internal/searcher/v1/searcher.pb.go

@@ -14,6 +14,8 @@ service SearcherService {
 
 // SearchRequest is set of parameters for a search.
 message SearchRequest {
+  reserved 9;
+
   // repo is the name of the repo to search (e.g. "github.com/gorilla/mux")
   string repo = 1;
 
@@ -54,11 +56,6 @@ message SearchRequest {
   // fetch will still happen in the background so future requests don't
   // have to wait.
   google.protobuf.Duration fetch_timeout = 8;
-
-  // feat_hybrid is a feature flag which enables hybrid search.
-  // Hybrid search will only search what has changed since Zoekt has
-  // indexed as well as including Zoekt results.
-  bool feat_hybrid = 9;
 }
 
 // SearchResponse is a message in the response stream for Search