fix(cli): deduplicate dag stat blocks by multihash

core/commands/dag/dag.go

@@ -377,7 +377,10 @@ var DagStatCmd = &cmds.Command{
 'ipfs dag stat' fetches a DAG and returns various statistics about it.
 Statistics include size and number of blocks.
 
-Note: This command skips duplicate blocks in reporting both size and the number of blocks
+Note: Duplicate blocks are identified by content hash (multihash) to reflect
+actual disk usage. Identical data referenced via different CIDs is counted
+once. 'dag export' uses CID-based keying and may include the same data
+multiple times if referenced by different CIDs.
 `,
 	},
 	Arguments: []cmds.Argument{

core/commands/dag/stat.go

@@ -7,8 +7,9 @@ import (
 
 	mdag "github.com/ipfs/boxo/ipld/merkledag"
 	"github.com/ipfs/boxo/ipld/merkledag/traverse"
-	cid "github.com/ipfs/go-cid"
 	cmds "github.com/ipfs/go-ipfs-cmds"
+	mh "github.com/multiformats/go-multihash"
+
 	"github.com/ipfs/kubo/core/commands/cmdenv"
 	"github.com/ipfs/kubo/core/commands/cmdutils"
 	"github.com/ipfs/kubo/core/commands/e"
@@ -26,7 +27,10 @@ func dagStat(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment)
 	}
 	nodeGetter := mdag.NewSession(req.Context, api.Dag())
 
-	cidSet := cid.NewSet()
+	// Use multihash set for deduplication to reflect actual storage.
+	// Since Kubo v0.12.0, blocks are stored by multihash, so identical
+	// data with different CIDs (e.g., CIDv0 vs CIDv1) is stored once.
+	mhSet := mh.NewSet()
 	dagStatSummary := &DagStatSummary{DagStatsArray: []*DagStat{}}
 	for _, a := range req.Arguments {
 		p, err := cmdutils.PathOrCidPath(a)
@@ -54,11 +58,11 @@ func dagStat(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment)
 				currentNodeSize := uint64(len(current.Node.RawData()))
 				dagstats.Size += currentNodeSize
 				dagstats.NumBlocks++
-				if !cidSet.Has(current.Node.Cid()) {
+				// Visit returns true if this multihash was not seen before
+				if mhSet.Visit(current.Node.Cid().Hash()) {
 					dagStatSummary.incrementTotalSize(currentNodeSize)
 				}
 				dagStatSummary.incrementRedundantSize(currentNodeSize)
-				cidSet.Add(current.Node.Cid())
 				if progressive {
 					if err := res.Emit(dagStatSummary); err != nil {
 						return err
@@ -74,7 +78,7 @@ func dagStat(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment)
 		}
 	}
 
-	dagStatSummary.UniqueBlocks = cidSet.Len()
+	dagStatSummary.UniqueBlocks = mhSet.Len()
 	dagStatSummary.calculateSummary()
 
 	if err := res.Emit(dagStatSummary); err != nil {

docs/changelogs/v0.40.md

@@ -11,7 +11,8 @@ This release was brought to you by the [Shipyard](https://ipshipyard.com/) team.
 - [Overview](#overview)
 - [🔦 Highlights](#-highlights)
   - [Routing V1 HTTP API now exposed by default](#routing-v1-http-api-now-exposed-by-default)
-  - [Track total size when adding pins](#track-total-size-when-adding-pins]
+  - [Track total size when adding pins](#track-total-size-when-adding-pins)
+  - [Fixed `ipfs dag stat` block counting](#fixed-ipfs-dag-stat-block-counting)
 - [📝 Changelog](#-changelog)
 - [👨‍👩‍👧‍👦 Contributors](#-contributors)
 
@@ -32,6 +33,10 @@ Example output:
 Fetched/Processed 336 nodes (83 MB)
 ```
 
+#### Fixed `ipfs dag stat` block counting
+
+Since Kubo v0.12.0, blocks are stored by multihash, so the same data is stored only once regardless of which CID references it. The `dag stat` command now reflects actual storage by deduplicating blocks by content hash (e.g., data referenced via both CIDv0 and CIDv1 is counted once). See `ipfs dag stat --help` for more details.
+
 ### 📝 Changelog
 
 ### 👨‍👩‍👧‍👦 Contributors

test/cli/dag_test.go

@@ -104,6 +104,27 @@ func TestDag(t *testing.T) {
 		stat := node.RunIPFS("dag", "stat", "--progress=false", node1Cid, node2Cid)
 		assert.Equal(t, content, stat.Stdout.Bytes())
 	})
+
+	t.Run("dag stat deduplicates by multihash", func(t *testing.T) {
+		t.Parallel()
+		node := harness.NewT(t).NewNode().Init().StartDaemon()
+
+		// Add content and get CIDv0 with dag-pb (not raw leaves)
+		cidV0 := node.IPFSAddStr("hello world", "--cid-version=0", "--raw-leaves=false")
+
+		// Convert to CIDv1 (same multihash, different CID)
+		cidV1 := node.IPFS("cid", "format", "-v", "1", "-b", "base32", cidV0).Stdout.Trimmed()
+
+		// Run dag stat with both CIDs - should deduplicate by multihash
+		stat := node.RunIPFS("dag", "stat", "--progress=false", "--enc=json", cidV0, cidV1)
+		var data Data
+		err := json.Unmarshal(stat.Stdout.Bytes(), &data)
+		require.NoError(t, err)
+
+		// Same block referenced via CIDv0 and CIDv1 should be counted once
+		assert.Equal(t, 1, data.UniqueBlocks, "same data via different CIDs should be 1 unique block")
+		assert.Equal(t, 2.0, data.Ratio, "ratio should be 2.0 (2 refs to 1 block)")
+	})
 }
 
 func TestDagImportFastProvide(t *testing.T) {