SERVER-52021: Create feature flag for support lookup and graphLookup into a sharded collection

5 files changed, 27 insertions, 24 deletions

diff --git a/src/mongo/db/pipeline/document_source_graph_lookup.cpp b/src/mongo/db/pipeline/document_source_graph_lookup.cpp
index c6550aef5f6..f550c2c68a2 100644
--- a/src/mongo/db/pipeline/document_source_graph_lookup.cpp
+++ b/src/mongo/db/pipeline/document_source_graph_lookup.cpp
@@ -49,9 +49,6 @@
 namespace mongo {
 
 namespace {
-bool foreignShardedLookupAllowed() {
-    return getTestCommandsEnabled() && internalQueryAllowShardedLookup.load();
-}
 
 // Parses $graphLookup 'from' field. The 'from' field must be a string with the exception of
 // 'local.system.tenantMigration.oplogView'.
@@ -210,7 +207,8 @@ void DocumentSourceGraphLookUp::doBreadthFirstSearch() {
     long long depth = 0;
     bool shouldPerformAnotherQuery;
     do {
-        if (!foreignShardedLookupAllowed()) {
+        if (!feature_flags::gFeatureFlagShardedLookup.isEnabled(
+                serverGlobalParams.featureCompatibility)) {
             // Enforce that the foreign collection must be unsharded for $graphLookup.
             _fromExpCtx->mongoProcessInterface->setExpectedShardVersion(
                 _fromExpCtx->opCtx, _fromExpCtx->ns, ChunkVersion::UNSHARDED());
@@ -244,7 +242,8 @@ void DocumentSourceGraphLookUp::doBreadthFirstSearch() {
             pipelineOpts.optimize = true;
             pipelineOpts.attachCursorSource = true;
             // By default, $graphLookup doesn't support a sharded 'from' collection.
-            pipelineOpts.allowTargetingShards = internalQueryAllowShardedLookup.load();
+            pipelineOpts.allowTargetingShards = feature_flags::gFeatureFlagShardedLookup.isEnabled(
+                serverGlobalParams.featureCompatibility);
             _variables.copyToExpCtx(_variablesParseState, _fromExpCtx.get());
             auto pipeline = Pipeline::makePipeline(_fromPipeline, _fromExpCtx, pipelineOpts);
             while (auto next = pipeline->getNext()) {
@@ -393,7 +392,9 @@ void DocumentSourceGraphLookUp::performSearch() {
         if (auto staleInfo = ex.extraInfo<StaleConfigInfo>()) {
             uassert(31428,
                     "Cannot run $graphLookup with sharded foreign collection",
-                    foreignShardedLookupAllowed() || !staleInfo->getVersionWanted() ||
+                    feature_flags::gFeatureFlagShardedLookup.isEnabled(
+                        serverGlobalParams.featureCompatibility) ||
+                        !staleInfo->getVersionWanted() ||
                         staleInfo->getVersionWanted() == ChunkVersion::UNSHARDED());
         }
         throw;
diff --git a/src/mongo/db/pipeline/document_source_lookup.cpp b/src/mongo/db/pipeline/document_source_lookup.cpp
index d34df7f095a..87b7992aff5 100644
--- a/src/mongo/db/pipeline/document_source_lookup.cpp
+++ b/src/mongo/db/pipeline/document_source_lookup.cpp
@@ -87,10 +87,6 @@ void lookupPipeValidator(const Pipeline& pipeline) {
     });
 }
 
-bool foreignShardedLookupAllowed() {
-    return getTestCommandsEnabled() && internalQueryAllowShardedLookup.load();
-}
-
 // Parses $lookup 'from' field. The 'from' field must be a string or one of the following
 // exceptions:
 // {from: {db: "config", coll: "cache.chunks.*"}, ...} or
@@ -310,7 +306,9 @@ StageConstraints DocumentSourceLookUp::constraints(Pipeline::SplitState) const {
     } else {
         // When $lookup on sharded foreign collections is allowed, the foreign collection is
         // sharded, and the stage is executing on mongos, the stage can run on mongos or any shard.
-        hostRequirement = (foreignShardedLookupAllowed() && pExpCtx->inMongos &&
+        hostRequirement = (feature_flags::gFeatureFlagShardedLookup.isEnabled(
+                               serverGlobalParams.featureCompatibility) &&
+                           pExpCtx->inMongos &&
                            pExpCtx->mongoProcessInterface->isSharded(pExpCtx->opCtx, _fromNs))
             ? HostTypeRequirement::kNone
             : HostTypeRequirement::kPrimaryShard;
@@ -371,7 +369,9 @@ DocumentSource::GetNextResult DocumentSourceLookUp::doGetNext() {
         if (auto staleInfo = ex.extraInfo<StaleConfigInfo>()) {
             uassert(51069,
                     "Cannot run $lookup with sharded foreign collection",
-                    foreignShardedLookupAllowed() || !staleInfo->getVersionWanted() ||
+                    feature_flags::gFeatureFlagShardedLookup.isEnabled(
+                        serverGlobalParams.featureCompatibility) ||
+                        !staleInfo->getVersionWanted() ||
                         staleInfo->getVersionWanted() == ChunkVersion::UNSHARDED());
         }
         throw;
@@ -408,7 +408,8 @@ std::unique_ptr<Pipeline, PipelineDeleter> DocumentSourceLookUp::buildPipeline(
     // Resolve the 'let' variables to values per the given input document.
     resolveLetVariables(inputDoc, &_fromExpCtx->variables);
 
-    if (!foreignShardedLookupAllowed()) {
+    if (!feature_flags::gFeatureFlagShardedLookup.isEnabled(
+            serverGlobalParams.featureCompatibility)) {
         // Enforce that the foreign collection must be unsharded for lookup.
         _fromExpCtx->mongoProcessInterface->setExpectedShardVersion(
             _fromExpCtx->opCtx, _fromExpCtx->ns, ChunkVersion::UNSHARDED());
@@ -421,7 +422,8 @@ std::unique_ptr<Pipeline, PipelineDeleter> DocumentSourceLookUp::buildPipeline(
         pipelineOpts.attachCursorSource = true;
         pipelineOpts.validator = lookupPipeValidator;
         // By default, $lookup doesnt support sharded 'from' collections.
-        pipelineOpts.allowTargetingShards = internalQueryAllowShardedLookup.load();
+        pipelineOpts.allowTargetingShards = feature_flags::gFeatureFlagShardedLookup.isEnabled(
+            serverGlobalParams.featureCompatibility);
         return Pipeline::makePipeline(_resolvedPipeline, _fromExpCtx, pipelineOpts);
     }
 
@@ -451,7 +453,9 @@ std::unique_ptr<Pipeline, PipelineDeleter> DocumentSourceLookUp::buildPipeline(
     if (!_cache->isServing()) {
         // The cache has either been abandoned or has not yet been built. Attach a cursor.
         pipeline = pExpCtx->mongoProcessInterface->attachCursorSourceToPipeline(
-            pipeline.release(), internalQueryAllowShardedLookup.load() /* allowTargetingShards*/);
+            pipeline.release(),
+            feature_flags::gFeatureFlagShardedLookup
+                .isEnabledAndIgnoreFCV() /* allowTargetingShards*/);
     }
 
     // If the cache has been abandoned, release it.
diff --git a/src/mongo/db/pipeline/document_source_lookup.h b/src/mongo/db/pipeline/document_source_lookup.h
index 75a2fc42a4e..29df6539f17 100644
--- a/src/mongo/db/pipeline/document_source_lookup.h
+++ b/src/mongo/db/pipeline/document_source_lookup.h
@@ -76,8 +76,8 @@ public:
          * Lookup from a sharded collection may not be allowed.
          */
         bool allowShardedForeignCollection(NamespaceString nss) const override final {
-            const bool foreignShardedAllowed =
-                getTestCommandsEnabled() && internalQueryAllowShardedLookup.load();
+            const bool foreignShardedAllowed = feature_flags::gFeatureFlagShardedLookup.isEnabled(
+                serverGlobalParams.featureCompatibility);
             if (foreignShardedAllowed) {
                 return true;
             }
diff --git a/src/mongo/db/query/query_feature_flags.idl b/src/mongo/db/query/query_feature_flags.idl
index 4c7cd6a1b46..1ce15a6fb19 100644
--- a/src/mongo/db/query/query_feature_flags.idl
+++ b/src/mongo/db/query/query_feature_flags.idl
@@ -60,3 +60,8 @@ feature_flags:
       description: "Feature flag for allowing use of topN family of accumulators"
       cpp_varname: gFeatureFlagExactTopNAccumulator
       default: false
+      
+    featureFlagShardedLookup:
+      description: "Feature flag for allowing $lookup/$graphLookup into a sharded collection"
+      cpp_varname: gFeatureFlagShardedLookup 
+      default: false
diff --git a/src/mongo/db/query/query_knobs.idl b/src/mongo/db/query/query_knobs.idl
index fb43fd9c4c2..24e265a7877 100644
--- a/src/mongo/db/query/query_knobs.idl
+++ b/src/mongo/db/query/query_knobs.idl
@@ -350,13 +350,6 @@ server_parameters:
     cpp_vartype: AtomicWord<bool>
     default: false
 
-  internalQueryAllowShardedLookup:
-    description: "If true, activates the incomplete sharded $lookup feature."
-    set_at: [ startup, runtime ]
-    cpp_varname: "internalQueryAllowShardedLookup"
-    cpp_vartype: AtomicWord<bool>
-    default: false
-
   internalQueryMaxJsEmitBytes:
     description: "Limits the vector of values emitted from a single document's call to JsEmit to the
         given size in bytes."