Indexing language: documentid

en/reference/writing/indexing-language.html

@@ -458,6 +458,16 @@ <h3 id="other-expressions">Other expressions</h3>
       </p>
     </td>
   </tr>
+  <tr>
+    <td><code>documentid [part]</code></td>
+    <td>
+      <p id="documentid">
+        Exposes ID of the document being processed, or, given an optional
+        argument, a single structural part of it as a string.
+        Valid <code>part</code> values are: <code>namespace, documenttype, group, number, specific</code>
+      </p>
+    </td>
+  </tr>
   <tr>
     <td><code>echo</code></td>
     <td>

en/writing/indexing.html

@@ -137,6 +137,38 @@ <h2 id="switch-example">Switch example</h2>
 </pre>
 
 
+<h2 id="documentid">documentid example</h2>
+
+<p>
+  The <code>documentid</code> expression allows taking whole or
+  a portion of a document ID and making it searchable.
+  Common uses:
+</p>
+  <ul>
+    <li>Hashing document ID into a stable value for sorting or a tie-breaker</li>
+    <li>Making the <a href="../schemas/documents.html#namespace">namespace</a> searchable</li>
+    <li>Eliminate duplication of document id as a field in feed requests</li>
+  </ul>
+<pre>
+schema doc {
+    document doc {
+    }
+    field stable_hash type int {
+        indexing: documentid | hash | attribute
+    }
+    field namespace type string {
+        indexing: documentid namespace | attribute
+        attribute: fast-search
+    }
+    field id type string {
+        indexing: documentid specific | attribute
+        attribute: fast-search
+    }
+}
+</pre>
+<p>
+  Available since {% include version.html version="8.741.10" %}.
+</p>
 
 <h2 id="combine-values-in-indexing-statements">Indexing statements example</h2>
 <p>
@@ -175,4 +207,3 @@ <h2 id="combine-values-in-indexing-statements">Indexing statements example</h2>
   <tr><td>field1 and field2</td><td>field1 and field2 are updated</td></tr>
   </tbody>
 </table>
-