diff --git a/pkg/chunk/aws/storage_client.go b/pkg/chunk/aws/storage_client.go
index 770f2a01e1..22839ca5de 100644
--- a/pkg/chunk/aws/storage_client.go
+++ b/pkg/chunk/aws/storage_client.go
@@ -250,6 +250,9 @@ func (a storageClient) BatchWrite(ctx context.Context, input chunk.WriteBatch) e
 	}
 
 	if valuesLeft := outstanding.Len() + unprocessed.Len(); valuesLeft > 0 {
+		if valuesLeft < 4 { // protect against logging lots of data
+			level.Info(util.Logger).Log("msg", "DynamoDB BatchWrite values left", "count", valuesLeft, "outstanding", outstanding, "unprocessed", unprocessed)
+		}
 		return fmt.Errorf("failed to write chunk, %d values remaining: %s", valuesLeft, backoff.Err())
 	}
 	return backoff.Err()
@@ -731,6 +734,7 @@ func (a storageClient) putS3Chunk(ctx context.Context, key string, buf []byte) e
 	})
 }
 
+// Slice of values returned; map key is attribute name
 type dynamoDBReadResponse []map[string]*dynamodb.AttributeValue
 
 func (b dynamoDBReadResponse) Len() int {
@@ -749,6 +753,7 @@ func (b dynamoDBReadResponse) Value(i int) []byte {
 	return chunkValue.B
 }
 
+// map key is table name; value is a slice of things to 'put'
 type dynamoDBWriteBatch map[string][]*dynamodb.WriteRequest
 
 func (b dynamoDBWriteBatch) Len() int {
@@ -795,6 +800,31 @@ func (b dynamoDBWriteBatch) TakeReqs(from dynamoDBWriteBatch, max int) {
 	}
 }
 
+func (b dynamoDBWriteBatch) String() string {
+	buf := &bytes.Buffer{}
+	for table, reqs := range b {
+		for _, req := range reqs {
+			item := req.PutRequest.Item
+			hash := ""
+			if hashAttr, ok := item[hashKey]; ok {
+				if hashAttr.S != nil {
+					hash = *hashAttr.S
+				}
+			}
+			var rnge, value []byte
+			if rangeAttr, ok := item[rangeKey]; ok {
+				rnge = rangeAttr.B
+			}
+			if valueAttr, ok := item[valueKey]; ok {
+				value = valueAttr.B
+			}
+			fmt.Fprintf(buf, "%s: %s,%.32s,%.32s; ", table, hash, rnge, value)
+		}
+	}
+	return buf.String()
+}
+
+// map key is table name
 type dynamoDBReadRequest map[string]*dynamodb.KeysAndAttributes
 
 func (b dynamoDBReadRequest) Len() int {