diff --git a/guix-data-service/model/nar.scm b/guix-data-service/model/nar.scm
index 9f607be..41e08fc 100644
--- a/guix-data-service/model/nar.scm
+++ b/guix-data-service/model/nar.scm
@@ -18,6 +18,8 @@
 (define-module (guix-data-service model nar)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-19)
+  #:use-module (srfi srfi-43)
+  #:use-module (srfi srfi-71)
   #:use-module (ice-9 match)
   #:use-module (web uri)
   #:use-module (squee)
@@ -56,26 +58,36 @@
                (or (narinfo-deriver narinfo) NULL)))))
          narinfos))
 
-  (let ((nar-ids
-         (vector->list
+  (let* ((nar-ids
+          new-ids
           (insert-missing-data-and-return-all-ids
            conn
            "nars"
            '(store_path hash_algorithm hash size system deriver)
-           (list->vector data)))))
+           (list->vector data)))
+         (new-narinfos
+          (filter-map
+           (lambda (nar-id narinfo)
+             (if (vector-any (lambda (x)
+                               (= x nar-id))
+                             new-ids)
+                 (cons nar-id narinfo)
+                 #f))
+           (vector->list nar-ids)
+           narinfos)))
 
     (let ((reference-data
            (concatenate
-            (map (lambda (nar-id narinfo)
-                   (map (lambda (reference)
-                          (simple-format
-                           #f
-                           "(~A, ~A)"
-                           nar-id
-                           (quote-string reference)))
-                        (narinfo-references narinfo)))
-                 nar-ids
-                 narinfos))))
+            (map (match-lambda
+                   ((nar-id . narinfo)
+                    (map (lambda (reference)
+                           (simple-format
+                            #f
+                            "(~A, ~A)"
+                            nar-id
+                            (quote-string reference)))
+                         (narinfo-references narinfo))))
+                 new-narinfos))))
       (unless (null? reference-data)
         (exec-query
          conn
@@ -83,9 +95,7 @@
           "
 INSERT INTO nar_references (nar_id, reference)
 VALUES "
-          (string-join reference-data ", ")
-          "
-ON CONFLICT DO NOTHING"))))
+          (string-join reference-data ", ")))))
 
     (exec-query
      conn
@@ -95,55 +105,51 @@ INSERT INTO nar_urls (nar_id, url, compression, file_size)
 VALUES "
       (string-join
        (concatenate
-        (map (lambda (nar-id narinfo)
-               (map (lambda (uri compression file-size)
-                      (simple-format
-                       #f
-                       "(~A, ~A, ~A, ~A)"
-                       nar-id
-                       (quote-string
-                        (uri->string uri))
-                       (quote-string compression)
-                       (or file-size "NULL")))
-                    (narinfo-uris narinfo)
-                    (narinfo-compressions narinfo)
-                    (narinfo-file-sizes narinfo)))
-             nar-ids
-             narinfos))
-       ", ")
-      "
-ON CONFLICT DO NOTHING"))
+        (map (match-lambda
+               ((nar-id . narinfo)
+                (map (lambda (uri compression file-size)
+                       (simple-format
+                        #f
+                        "(~A, ~A, ~A, ~A)"
+                        nar-id
+                        (quote-string
+                         (uri->string uri))
+                        (quote-string compression)
+                        (or file-size "NULL")))
+                     (narinfo-uris narinfo)
+                     (narinfo-compressions narinfo)
+                     (narinfo-file-sizes narinfo))))
+             new-narinfos))
+       ", ")))
 
-    (for-each (lambda (nar-id narinfo)
-                (let ((narinfo-signature-data-id
-                       (narinfo-signature->data-id conn narinfo)))
+    (for-each (match-lambda
+                ((nar-id . narinfo)
+                 (let ((narinfo-signature-data-id
+                        (narinfo-signature->data-id conn narinfo)))
 
-                  (exec-query
-                   conn
-                   (string-append
-                    "
+                   (exec-query
+                    conn
+                    (string-append
+                     "
 INSERT INTO narinfo_signatures (nar_id, narinfo_signature_data_id)
 VALUES "
-                    (simple-format
-                     #f
-                     "(~A,~A)"
-                     nar-id
-                     narinfo-signature-data-id)
-                    "
-ON CONFLICT DO NOTHING"))
+                     (simple-format
+                      #f
+                      "(~A,~A)"
+                      nar-id
+                      narinfo-signature-data-id)))
 
-                  (exec-query
-                   conn
-                   (string-append
-                    "
+                   (exec-query
+                    conn
+                    (string-append
+                     "
 INSERT INTO narinfo_fetch_records (narinfo_signature_data_id, build_server_id)
 VALUES ($1, $2)")
-                   (list (number->string narinfo-signature-data-id)
-                         (number->string build-server-id)))))
-              nar-ids
-              narinfos)
+                    (list (number->string narinfo-signature-data-id)
+                          (number->string build-server-id))))))
+              new-narinfos)
 
-    nar-ids))
+    (vector->list nar-ids)))
 
 (define (sexp->json-string sexp)
   (define (transform x)