diff --git a/eden/mononoke/walker/src/corpus.rs b/eden/mononoke/walker/src/corpus.rs
index 1f34ec9eff..07e3cf1e16 100644
--- a/eden/mononoke/walker/src/corpus.rs
+++ b/eden/mononoke/walker/src/corpus.rs
@@ -416,6 +416,7 @@ pub async fn corpus<'a>(
         logger,
         datasources,
         walk_params,
+        &[NodeType::FileContent],
         None,
         walk_state,
         make_sink,
diff --git a/eden/mononoke/walker/src/graph.rs b/eden/mononoke/walker/src/graph.rs
index 3297ac9f94..842321ca99 100644
--- a/eden/mononoke/walker/src/graph.rs
+++ b/eden/mononoke/walker/src/graph.rs
@@ -439,6 +439,7 @@ pub enum FileContentData {
 /// e.g. file content streams are passed to you to read, they aren't pre-loaded to bytes.
 pub enum NodeData {
     ErrorAsData(Node),
+    NotRequired,
     // Bonsai
     Bookmark(ChangesetId),
     BonsaiChangeset(BonsaiChangeset),
diff --git a/eden/mononoke/walker/src/scrub.rs b/eden/mononoke/walker/src/scrub.rs
index ef2edd170a..763414dc4e 100644
--- a/eden/mononoke/walker/src/scrub.rs
+++ b/eden/mononoke/walker/src/scrub.rs
@@ -396,6 +396,7 @@ pub async fn scrub_objects<'a>(
         logger,
         datasources,
         walk_params,
+        &[NodeType::FileContent],
         None,
         walk_state,
         make_sink,
diff --git a/eden/mononoke/walker/src/sizing.rs b/eden/mononoke/walker/src/sizing.rs
index 325a1bd8b1..750f0bf425 100644
--- a/eden/mononoke/walker/src/sizing.rs
+++ b/eden/mononoke/walker/src/sizing.rs
@@ -372,6 +372,7 @@ pub async fn compression_benefit<'a>(
         logger,
         datasources,
         walk_params,
+        &[NodeType::FileContent],
         None,
         walk_state,
         make_sink,
diff --git a/eden/mononoke/walker/src/tail.rs b/eden/mononoke/walker/src/tail.rs
index 0cee01e532..1888eb312c 100644
--- a/eden/mononoke/walker/src/tail.rs
+++ b/eden/mononoke/walker/src/tail.rs
@@ -5,7 +5,7 @@
  * GNU General Public License version 2.
  */
 
-use crate::graph::EdgeType;
+use crate::graph::{EdgeType, NodeType};
 use crate::setup::{RepoWalkDatasources, RepoWalkParams};
 use crate::walk::{walk_exact, StepRoute, WalkVisitor};
 
@@ -16,7 +16,7 @@ use fbinit::FacebookInit;
 use futures::{future::Future, stream::BoxStream};
 use scuba_ext::ScubaSampleBuilder;
 use slog::Logger;
-use std::collections::HashSet;
+use std::{collections::HashSet, iter::FromIterator};
 use tokio::time::{Duration, Instant};
 
 #[derive(Clone)]
@@ -30,6 +30,7 @@ pub async fn walk_exact_tail<RunFac, SinkFac, SinkOut, V, VOut, Route>(
     logger: Logger,
     datasources: RepoWalkDatasources,
     walk_params: RepoWalkParams,
+    required_node_data_types: &[NodeType],
     always_emit_edge_types: Option<HashSet<EdgeType>>,
     visitor: V,
     make_run: RunFac,
@@ -51,6 +52,9 @@ where
     } else {
         HashSet::new()
     };
+    let required_node_data_types =
+        HashSet::from_iter(required_node_data_types.into_iter().cloned());
+
     loop {
         cloned!(make_run, repo, mut scuba_builder, visitor,);
 
@@ -72,6 +76,7 @@ where
             walk_params.error_as_data_edge_types.clone(),
             walk_params.include_edge_types.clone(),
             always_emit_edge_types.clone(),
+            required_node_data_types.clone(),
             scuba_builder,
             keep_edge_paths,
         );
diff --git a/eden/mononoke/walker/src/validate.rs b/eden/mononoke/walker/src/validate.rs
index be5fa05d84..d7a26c705b 100644
--- a/eden/mononoke/walker/src/validate.rs
+++ b/eden/mononoke/walker/src/validate.rs
@@ -688,6 +688,7 @@ pub async fn validate<'a>(
         logger,
         datasources,
         walk_params,
+        &[NodeType::BonsaiPhaseMapping],
         Some(always_emit_edge_types),
         stateful_visitor,
         make_sink,
diff --git a/eden/mononoke/walker/src/walk.rs b/eden/mononoke/walker/src/walk.rs
index c1ac7af8d7..bff30127c5 100644
--- a/eden/mononoke/walker/src/walk.rs
+++ b/eden/mononoke/walker/src/walk.rs
@@ -185,7 +185,10 @@ fn bookmark_step<'a, V: VisitOne>(
             checker.add_edge(&mut edges, EdgeType::BookmarkToBonsaiHgMapping, || {
                 Node::BonsaiHgMapping(bcs_id)
             });
-            future::ok(StepOutput(NodeData::Bookmark(bcs_id), edges))
+            future::ok(StepOutput(
+                checker.step_data(NodeType::Bookmark, || NodeData::Bookmark(bcs_id)),
+                edges,
+            ))
         }
         None => future::err(format_err!("Unknown Bookmark {}", b)),
     })
@@ -208,22 +211,33 @@ fn published_bookmarks_step<V: VisitOne>(
             || Node::BonsaiHgMapping(bcs_id.clone()),
         );
     }
-    future::ok(StepOutput(NodeData::PublishedBookmarks, edges))
+    future::ok(StepOutput(
+        checker.step_data(NodeType::PublishedBookmarks, || {
+            NodeData::PublishedBookmarks
+        }),
+        edges,
+    ))
 }
 
-fn bonsai_phase_step(
-    ctx: &CoreContext,
+fn bonsai_phase_step<'a, V: VisitOne>(
+    ctx: &'a CoreContext,
+    checker: &'a Checker<V>,
     phases_store: Arc<dyn Phases>,
     bcs_id: ChangesetId,
-) -> impl Future<Output = Result<StepOutput, Error>> {
+) -> impl Future<Output = Result<StepOutput, Error>> + 'a {
     phases_store
         .get_public(ctx.clone(), vec![bcs_id], true)
         .map(move |public| public.contains(&bcs_id))
-        .map(|is_public| {
-            let phase = if is_public { Some(Phase::Public) } else { None };
-            StepOutput(NodeData::BonsaiPhaseMapping(phase), vec![])
-        })
         .compat()
+        .map_ok(move |is_public| {
+            let phase = if is_public { Some(Phase::Public) } else { None };
+            StepOutput(
+                checker.step_data(NodeType::BonsaiPhaseMapping, || {
+                    NodeData::BonsaiPhaseMapping(phase)
+                }),
+                vec![],
+            )
+        })
 }
 
 async fn bonsai_changeset_step<V: VisitOne>(
@@ -269,12 +283,16 @@ async fn bonsai_changeset_step<V: VisitOne>(
         EdgeType::BonsaiChangesetToBonsaiFsnodeMapping,
         || Node::BonsaiFsnodeMapping(*bcs_id),
     );
-    Ok(StepOutput(NodeData::BonsaiChangeset(bcs), edges))
+    Ok(StepOutput(
+        checker.step_data(NodeType::BonsaiChangeset, || NodeData::BonsaiChangeset(bcs)),
+        edges,
+    ))
 }
 
-fn file_content_step(
+fn file_content_step<V: VisitOne>(
     ctx: CoreContext,
     repo: &BlobRepo,
+    checker: &Checker<V>,
     id: ContentId,
 ) -> Result<StepOutput, Error> {
     let s = filestore::fetch_stream(repo.blobstore(), ctx, id)
@@ -282,7 +300,9 @@ fn file_content_step(
         .compat();
     // We don't force file loading here, content may not be needed
     Ok(StepOutput(
-        NodeData::FileContent(FileContentData::ContentStream(Box::pin(s))),
+        checker.step_data(NodeType::FileContent, || {
+            NodeData::FileContent(FileContentData::ContentStream(Box::pin(s)))
+        }),
         vec![],
     ))
 }
@@ -319,9 +339,19 @@ fn file_content_metadata_step<'a, V: VisitOne>(
                     EdgeType::FileContentMetadataToGitSha1Alias,
                     || Node::AliasContentMapping(Alias::GitSha1(metadata.git_sha1.sha1())),
                 );
-                StepOutput(NodeData::FileContentMetadata(Some(metadata)), edges)
+                StepOutput(
+                    checker.step_data(NodeType::FileContentMetadata, || {
+                        NodeData::FileContentMetadata(Some(metadata))
+                    }),
+                    edges,
+                )
             }
-            Some(None) | None => StepOutput(NodeData::FileContentMetadata(None), vec![]),
+            Some(None) | None => StepOutput(
+                checker.step_data(NodeType::FileContentMetadata, || {
+                    NodeData::FileContentMetadata(None)
+                }),
+                vec![],
+            ),
         })
         .compat()
 }
@@ -390,9 +420,19 @@ fn bonsai_to_hg_mapping_step<'a, V: 'a + VisitOne>(
                 checker.add_edge(&mut edges, EdgeType::BonsaiHgMappingToHgChangeset, || {
                     Node::HgChangeset(hg_cs_id)
                 });
-                StepOutput(NodeData::BonsaiHgMapping(Some(hg_cs_id)), edges)
+                StepOutput(
+                    checker.step_data(NodeType::BonsaiHgMapping, || {
+                        NodeData::BonsaiHgMapping(Some(hg_cs_id))
+                    }),
+                    edges,
+                )
             }
-            None => StepOutput(NodeData::BonsaiHgMapping(None), vec![]),
+            None => StepOutput(
+                checker.step_data(NodeType::BonsaiHgMapping, || {
+                    NodeData::BonsaiHgMapping(None)
+                }),
+                vec![],
+            ),
         })
         .compat()
 }
@@ -412,9 +452,19 @@ fn hg_to_bonsai_mapping_step<'a, V: VisitOne>(
                     EdgeType::HgBonsaiMappingToBonsaiChangeset,
                     || Node::BonsaiChangeset(bcs_id),
                 );
-                StepOutput(NodeData::HgBonsaiMapping(Some(bcs_id)), edges)
+                StepOutput(
+                    checker.step_data(NodeType::HgBonsaiMapping, || {
+                        NodeData::HgBonsaiMapping(Some(bcs_id))
+                    }),
+                    edges,
+                )
             }
-            None => StepOutput(NodeData::HgBonsaiMapping(None), vec![]),
+            None => StepOutput(
+                checker.step_data(NodeType::HgBonsaiMapping, || {
+                    NodeData::HgBonsaiMapping(None)
+                }),
+                vec![],
+            ),
         })
         .compat()
 }
@@ -437,7 +487,10 @@ fn hg_changeset_step<'a, V: VisitOne>(
                     Node::HgChangeset(HgChangesetId::new(p))
                 });
             }
-            StepOutput(NodeData::HgChangeset(hgchangeset), edges)
+            StepOutput(
+                checker.step_data(NodeType::HgChangeset, || NodeData::HgChangeset(hgchangeset)),
+                edges,
+            )
         })
 }
 
@@ -460,7 +513,12 @@ fn hg_file_envelope_step<'a, V: 'a + VisitOne>(
                     || Node::FileContent(envelope.content_id()),
                     || path.cloned(),
                 );
-                StepOutput(NodeData::HgFileEnvelope(envelope), edges)
+                StepOutput(
+                    checker.step_data(NodeType::HgFileEnvelope, || {
+                        NodeData::HgFileEnvelope(envelope)
+                    }),
+                    edges,
+                )
             }
         })
 }
@@ -511,9 +569,17 @@ fn hg_file_node_step<'a, V: VisitOne>(
                         ))
                     })
                 }
-                StepOutput(NodeData::HgFileNode(Some(file_node_info)), edges)
+                StepOutput(
+                    checker.step_data(NodeType::HgFileNode, || {
+                        NodeData::HgFileNode(Some(file_node_info))
+                    }),
+                    edges,
+                )
             }
-            None => StepOutput(NodeData::HgFileNode(None), vec![]),
+            None => StepOutput(
+                checker.step_data(NodeType::HgFileNode, || NodeData::HgFileNode(None)),
+                vec![],
+            ),
         })
         .compat()
 }
@@ -555,7 +621,10 @@ fn hg_manifest_step<'a, V: VisitOne>(
                     Node::HgManifest((full_path, hg_child_manifest_id))
                 })
             }
-            StepOutput(NodeData::HgManifest(hgmanifest), edges)
+            StepOutput(
+                checker.step_data(NodeType::HgManifest, || NodeData::HgManifest(hgmanifest)),
+                edges,
+            )
         })
 }
 
@@ -574,7 +643,12 @@ fn alias_content_mapping_step<'a, V: VisitOne>(
                 EdgeType::AliasContentMappingToFileContent,
                 || Node::FileContent(content_id),
             );
-            StepOutput(NodeData::AliasContentMapping(content_id), edges)
+            StepOutput(
+                checker.step_data(NodeType::AliasContentMapping, || {
+                    NodeData::AliasContentMapping(content_id)
+                }),
+                edges,
+            )
         })
         .map_err(Error::from)
 }
@@ -598,11 +672,18 @@ async fn bonsai_to_fsnode_mapping_step<V: VisitOne>(
             Node::Fsnode((WrappedPath::Root, *root_fsnode_id.fsnode_id()))
         });
         Ok(StepOutput(
-            NodeData::BonsaiFsnodeMapping(Some(*root_fsnode_id.fsnode_id())),
+            checker.step_data(NodeType::BonsaiFsnodeMapping, || {
+                NodeData::BonsaiFsnodeMapping(Some(*root_fsnode_id.fsnode_id()))
+            }),
             edges,
         ))
     } else {
-        Ok(StepOutput(NodeData::BonsaiFsnodeMapping(None), vec![]))
+        Ok(StepOutput(
+            checker.step_data(NodeType::BonsaiFsnodeMapping, || {
+                NodeData::BonsaiFsnodeMapping(None)
+            }),
+            vec![],
+        ))
     }
 }
 
@@ -645,7 +726,10 @@ async fn fsnode_step<V: VisitOne>(
         }
     }
 
-    Ok(StepOutput(NodeData::Fsnode(fsnode), edges))
+    Ok(StepOutput(
+        checker.step_data(NodeType::Fsnode, || NodeData::Fsnode(fsnode)),
+        edges,
+    ))
 }
 
 /// Expand nodes where check for a type is used as a check for other types.
@@ -676,6 +760,7 @@ pub fn expand_checked_nodes(children: &mut Vec<OutgoingEdge>) -> () {
 struct Checker<V: VisitOne> {
     include_edge_types: HashSet<EdgeType>,
     always_emit_edge_types: HashSet<EdgeType>,
+    required_node_data_types: HashSet<NodeType>,
     keep_edge_paths: bool,
     visitor: V,
 }
@@ -746,6 +831,18 @@ impl<V: VisitOne> Checker<V> {
         }
         None
     }
+
+    // Only add the node data if requested
+    fn step_data<D>(&self, t: NodeType, data_fn: D) -> NodeData
+    where
+        D: FnOnce() -> NodeData,
+    {
+        if self.required_node_data_types.contains(&t) {
+            data_fn()
+        } else {
+            NodeData::NotRequired
+        }
+    }
 }
 
 /// Walk the graph from one or more starting points,  providing stream of data for later reduction
@@ -760,6 +857,7 @@ pub fn walk_exact<V, VOut, Route>(
     error_as_data_edge_types: HashSet<EdgeType>,
     include_edge_types: HashSet<EdgeType>,
     always_emit_edge_types: HashSet<EdgeType>,
+    required_node_data_types: HashSet<NodeType>,
     scuba: ScubaSampleBuilder,
     keep_edge_paths: bool,
 ) -> BoxStream<'static, Result<VOut, Error>>
@@ -791,6 +889,7 @@ where
         always_emit_edge_types,
         keep_edge_paths,
         visitor: visitor.clone(),
+        required_node_data_types,
     });
 
     published_bookmarks
@@ -896,7 +995,7 @@ where
                 repo.get_changeset_fetcher(),
                 heads_fetcher.clone(),
             );
-            bonsai_phase_step(&ctx, phases_store, bcs_id).await
+            bonsai_phase_step(&ctx, &checker, phases_store, bcs_id).await
         }
         Node::PublishedBookmarks => {
             published_bookmarks_step(published_bookmarks.clone(), &checker).await
@@ -925,7 +1024,9 @@ where
             hg_manifest_step(ctx.clone(), &repo, &checker, path, hg_manifest_id).await
         }
         // Content
-        Node::FileContent(content_id) => file_content_step(ctx.clone(), &repo, content_id),
+        Node::FileContent(content_id) => {
+            file_content_step(ctx.clone(), &repo, &checker, content_id)
+        }
         Node::FileContentMetadata(content_id) => {
             file_content_metadata_step(ctx.clone(), &repo, &checker, content_id, enable_derive)
                 .await