How to correctly add an attribute to the Sphinx index?

Question

PHP

I form the XML:

$xmlwriter = new xmlWriter();
$xmlwriter->openMemory();
$xmlwriter->setIndent(true);
$xmlwriter->startDocument('1.0','UTF-8');
$xmlwriter->startElement('sphinx:docset');

  $xmlwriter->startElement('sphinx:schema');

       $xmlwriter->startElement('spinx:attribute');
         $xmlwriter->writeAttribute("name", "path");
         $xmlwriter->writeAttribute("type", "string");
       $xmlwriter->endElement(); // attr

    $xmlwriter->startElement('sphinx:field');
       $xmlwriter->writeAttribute("name", "content");
    $xmlwriter->endElement(); // field

  $xmlwriter->endElement(); // schema

  $xmlwriter->startElement('sphinx:document');
    $xmlwriter->writeAttribute("id", 1);
    $xmlwriter->writeAttribute("path", "TEST_ATTRIBUTE");
    $xmlwriter->startElement("content");
        $xmlwriter->text("TEST_CONTENT");
        $xmlwriter->endElement(); // field
    $xmlwriter->endElement(); // doc

  $xmlwriter->endElement(); // docset

print $xmlwriter->outputMemory(true);

The result is:

<?xml version="1.0" encoding="UTF-8"?>
<sphinx:docset>
 <sphinx:schema>
  <spinx:attribute name="path" type="string"/>
  <sphinx:field name="content"/>
 </sphinx:schema>
 <sphinx:document id="1" path="TEST_ATTRIBUTE">
  <content>TEST_CONTENT</content>
 </sphinx:document>
</sphinx:docset>

Import into index:

# indexer --rotate --all 
Sphinx 2.2.11-id64-release (95ae9a6)
indexing index 'test1'...
WARNING: Attribute count is 0: switching to none docinfo
collected 3 docs, 0.0 MB

The search works, but the attribute does not get into the index.
How to add an attribute correctly?

Answer 1

Understood:

$xmlwriter = new xmlWriter();
$xmlwriter->openMemory();
$xmlwriter->setIndent(true);
$xmlwriter->startDocument('1.0','UTF-8');
$xmlwriter->startElement('sphinx:docset');

  $xmlwriter->startElement('sphinx:schema');
   $xmlwriter->startElement('sphinx:field');
          $xmlwriter->writeAttribute("name", "content");
    $xmlwriter->endElement(); // field
    $xmlwriter->startElement('sphinx:attr');
         $xmlwriter->writeAttribute("name", "path");
         $xmlwriter->writeAttribute("type", "string");
    $xmlwriter->endElement(); // attr
  $xmlwriter->endElement(); // schema

  $xmlwriter->startElement('sphinx:document');
        $xmlwriter->writeAttribute("id", 1);
        $xmlwriter->startElement("content");
              $xmlwriter->text("TEST_CONTENT2");
       $xmlwriter->endElement(); // field
       $xmlwriter->startElement("path");
             $xmlwriter->text("TEST_ATTRIBUTE2");
      $xmlwriter->endElement(); // attr
   $xmlwriter->endElement(); // doc

$xmlwriter->endElement(); // docset