diff --git a/core/lib/Drupal/Core/Database/StatementEmpty.php b/core/lib/Drupal/Core/Database/StatementEmpty.php
index 84ccb6a2ab5..4336fa11f4b 100644
--- a/core/lib/Drupal/Core/Database/StatementEmpty.php
+++ b/core/lib/Drupal/Core/Database/StatementEmpty.php
@@ -18,7 +18,7 @@ use Iterator;
  * database.  Calling code can then treat it the same as if it were an actual
  * result set that happens to contain no records.
  *
- * @see SearchQuery
+ * @see Drupal\search\SearchQuery
  */
 class StatementEmpty implements Iterator, StatementInterface {
 
diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index b5ed7e8e0c7..a59a5c7efb3 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -1725,7 +1725,7 @@ function node_search_admin() {
  */
 function node_search_execute($keys = NULL, $conditions = NULL) {
   // Build matching conditions
-  $query = db_select('search_index', 'i', array('target' => 'slave'))->extend('SearchQuery')->extend('PagerDefault');
+  $query = db_select('search_index', 'i', array('target' => 'slave'))->extend('Drupal\search\SearchQuery')->extend('PagerDefault');
   $query->join('node', 'n', 'n.nid = i.sid');
   $query
     ->condition('n.status', 1)
diff --git a/core/modules/search/search.api.php b/core/modules/search/search.api.php
index 534c1e8721f..cf8192242ed 100644
--- a/core/modules/search/search.api.php
+++ b/core/modules/search/search.api.php
@@ -162,10 +162,10 @@ function hook_search_admin() {
  *
  * If your module uses hook_update_index() and search_index() to index its
  * items, use table 'search_index' aliased to 'i' as the main table in your
- * query, with the 'SearchQuery' extension. You can join to your module's table
- * using the 'i.sid' field, which will contain the $sid values you provided to
- * search_index(). Add the main keywords to the query by using method
- * searchExpression(). The functions search_expression_extract() and
+ * query, with the 'Drupal\search\SearchQuery' extension. You can join to your
+ * module's table using the 'i.sid' field, which will contain the $sid values
+ * you provided to search_index(). Add the main keywords to the query by using
+ * method searchExpression(). The functions search_expression_extract() and
  * search_expression_insert() may also be helpful for adding custom search
  * parameters to the search expression.
  *
@@ -195,7 +195,7 @@ function hook_search_admin() {
  */
 function hook_search_execute($keys = NULL, $conditions = NULL) {
   // Build matching conditions
-  $query = db_select('search_index', 'i', array('target' => 'slave'))->extend('SearchQuery')->extend('PagerDefault');
+  $query = db_select('search_index', 'i', array('target' => 'slave'))->extend('Drupal\search\SearchQuery')->extend('PagerDefault');
   $query->join('node', 'n', 'n.nid = i.sid');
   $query
     ->condition('n.status', 1)
diff --git a/core/modules/search/search.extender.inc b/core/modules/search/search.extender.inc
deleted file mode 100644
index 73f783652f6..00000000000
--- a/core/modules/search/search.extender.inc
+++ /dev/null
@@ -1,511 +0,0 @@
-<?php
-
-use Drupal\Core\Database\Query\SelectExtender;
-use Drupal\Core\Database\StatementEmpty;
-
-/**
- * @file
- * Search query extender and helper functions.
- */
-
-/**
- * Do a query on the full-text search index for a word or words.
- *
- * This function is normally only called by each module that supports the
- * indexed search (and thus, implements hook_update_index()).
- *
- * Results are retrieved in two logical passes. However, the two passes are
- * joined together into a single query. And in the case of most simple
- * queries the second pass is not even used.
- *
- * The first pass selects a set of all possible matches, which has the benefit
- * of also providing the exact result set for simple "AND" or "OR" searches.
- *
- * The second portion of the query further refines this set by verifying
- * advanced text conditions (such as negative or phrase matches).
- *
- * The used query object has the tag 'search_$module' and can be further
- * extended with hook_query_alter().
- */
-class SearchQuery extends SelectExtender {
-  /**
-   * The search query that is used for searching.
-   *
-   * @var string
-   */
-  protected $searchExpression;
-
-  /**
-   * Type of search (search module).
-   *
-   * This maps to the value of the type column in search_index, and is equal
-   * to the machine-readable name of the module that implements
-   * hook_search_info().
-   *
-   * @var string
-   */
-  protected $type;
-
-  /**
-   * Positive and negative search keys.
-   *
-   * @var array
-   */
-  protected $keys = array('positive' => array(), 'negative' => array());
-
-  /**
-   * Indicates whether the first pass query requires complex conditions (LIKE).
-   *
-   * @var boolean.
-   */
-  protected $simple = TRUE;
-
-  /**
-   * Conditions that are used for exact searches.
-   *
-   * This is always used for the second pass query but not for the first pass,
-   * unless $this->simple is FALSE.
-   *
-   * @var DatabaseCondition
-   */
-  protected $conditions;
-
-  /**
-   * Indicates how many matches for a search query are necessary.
-   *
-   * @var int
-   */
-  protected $matches = 0;
-
-  /**
-   * Array of search words.
-   *
-   * These words have to match against {search_index}.word.
-   *
-   * @var array
-   */
-  protected $words = array();
-
-  /**
-   * Multiplier for the normalized search score.
-   *
-   * This value is calculated by the first pass query and multiplied with the
-   * actual score of a specific word to make sure that the resulting calculated
-   * score is between 0 and 1.
-   *
-   * @var float
-   */
-  protected $normalize;
-
-  /**
-   * Indicates whether the first pass query has been executed.
-   *
-   * @var boolean
-   */
-  protected $executedFirstPass = FALSE;
-
-  /**
-   * Stores score expressions.
-   *
-   * @var array
-   */
-  protected $scores = array();
-
-  /**
-   * Stores arguments for score expressions.
-   *
-   * @var array
-   */
-  protected $scoresArguments = array();
-
-  /**
-   * Total value of all the multipliers.
-   *
-   * @var array
-   */
-  protected $multiply = array();
-
-  /**
-   * Whether or not search expressions were ignored.
-   *
-   * The maximum number of AND/OR combinations exceeded can be configured to
-   * avoid Denial-of-Service attacks. Expressions beyond the limit are ignored.
-   *
-   * @var boolean
-   */
-  protected $expressionsIgnored = FALSE;
-
-  /**
-   * Sets up the search query expression.
-   *
-   * @param $query
-   *   A search query string, which can contain options.
-   * @param $module
-   *   The search module. This maps to {search_index}.type in the database.
-   *
-   * @return
-   *   The SearchQuery object.
-   */
-  public function searchExpression($expression, $module) {
-    $this->searchExpression = $expression;
-    $this->type = $module;
-
-    return $this;
-  }
-
-  /**
-   * Applies a search option and removes it from the search query string.
-   *
-   * These options are in the form option:value,value2,value3.
-   *
-   * @param $option
-   *   Name of the option.
-   * @param $column
-   *   Name of the database column to which the value should be applied.
-   *
-   * @return
-   *   TRUE if a value for that option was found, FALSE if not.
-   */
-  public function setOption($option, $column) {
-    if ($values = search_expression_extract($this->searchExpression, $option)) {
-      $or = db_or();
-      foreach (explode(',', $values) as $value) {
-        $or->condition($column, $value);
-      }
-      $this->condition($or);
-      $this->searchExpression = search_expression_insert($this->searchExpression, $option);
-      return TRUE;
-    }
-    return FALSE;
-  }
-
-  /**
-   * Parses the search query into SQL conditions.
-   *
-   * We build two queries that match the dataset bodies.
-   */
-  protected function parseSearchExpression() {
-    // Matchs words optionally prefixed by a dash. A word in this case is
-    // something between two spaces, optionally quoted.
-    preg_match_all('/ (-?)("[^"]+"|[^" ]+)/i', ' ' .  $this->searchExpression , $keywords, PREG_SET_ORDER);
-
-    if (count($keywords) ==  0) {
-      return;
-    }
-
-    // Classify tokens.
-    $or = FALSE;
-    $warning = '';
-    $limit_combinations = variable_get('search_and_or_limit', 7);
-    // The first search expression does not count as AND.
-    $and_count = -1;
-    $or_count = 0;
-    foreach ($keywords as $match) {
-      if ($or_count && $and_count + $or_count >= $limit_combinations) {
-        // Ignore all further search expressions to prevent Denial-of-Service
-        // attacks using a high number of AND/OR combinations.
-        $this->expressionsIgnored = TRUE;
-        break;
-      }
-      $phrase = FALSE;
-      // Strip off phrase quotes.
-      if ($match[2]{0} == '"') {
-        $match[2] = substr($match[2], 1, -1);
-        $phrase = TRUE;
-        $this->simple = FALSE;
-      }
-      // Simplify keyword according to indexing rules and external
-      // preprocessors. Use same process as during search indexing, so it
-      // will match search index.
-      $words = search_simplify($match[2]);
-      // Re-explode in case simplification added more words, except when
-      // matching a phrase.
-      $words = $phrase ? array($words) : preg_split('/ /', $words, -1, PREG_SPLIT_NO_EMPTY);
-      // Negative matches.
-      if ($match[1] == '-') {
-        $this->keys['negative'] = array_merge($this->keys['negative'], $words);
-      }
-      // OR operator: instead of a single keyword, we store an array of all
-      // OR'd keywords.
-      elseif ($match[2] == 'OR' && count($this->keys['positive'])) {
-        $last = array_pop($this->keys['positive']);
-        // Starting a new OR?
-        if (!is_array($last)) {
-          $last = array($last);
-        }
-        $this->keys['positive'][] = $last;
-        $or = TRUE;
-        $or_count++;
-        continue;
-      }
-      // AND operator: implied, so just ignore it.
-      elseif ($match[2] == 'AND' || $match[2] == 'and') {
-        $warning = $match[2];
-        continue;
-      }
-
-      // Plain keyword.
-      else {
-        if ($match[2] == 'or') {
-          $warning = $match[2];
-        }
-        if ($or) {
-          // Add to last element (which is an array).
-          $this->keys['positive'][count($this->keys['positive']) - 1] = array_merge($this->keys['positive'][count($this->keys['positive']) - 1], $words);
-        }
-        else {
-          $this->keys['positive'] = array_merge($this->keys['positive'], $words);
-          $and_count++;
-        }
-      }
-      $or = FALSE;
-    }
-
-    // Convert keywords into SQL statements.
-    $this->conditions = db_and();
-    $simple_and = FALSE;
-    $simple_or = FALSE;
-    // Positive matches.
-    foreach ($this->keys['positive'] as $key) {
-      // Group of ORed terms.
-      if (is_array($key) && count($key)) {
-        $simple_or = TRUE;
-        $any = FALSE;
-        $queryor = db_or();
-        foreach ($key as $or) {
-          list($num_new_scores) = $this->parseWord($or);
-          $any |= $num_new_scores;
-          $queryor->condition('d.data', "% $or %", 'LIKE');
-        }
-        if (count($queryor)) {
-          $this->conditions->condition($queryor);
-          // A group of OR keywords only needs to match once.
-          $this->matches += ($any > 0);
-        }
-      }
-      // Single ANDed term.
-      else {
-        $simple_and = TRUE;
-        list($num_new_scores, $num_valid_words) = $this->parseWord($key);
-        $this->conditions->condition('d.data', "% $key %", 'LIKE');
-        if (!$num_valid_words) {
-          $this->simple = FALSE;
-        }
-        // Each AND keyword needs to match at least once.
-        $this->matches += $num_new_scores;
-      }
-    }
-    if ($simple_and && $simple_or) {
-      $this->simple = FALSE;
-    }
-    // Negative matches.
-    foreach ($this->keys['negative'] as $key) {
-      $this->conditions->condition('d.data', "% $key %", 'NOT LIKE');
-      $this->simple = FALSE;
-    }
-
-    if ($warning == 'or') {
-      drupal_set_message(t('Search for either of the two terms with uppercase <strong>OR</strong>. For example, <strong>cats OR dogs</strong>.'));
-    }
-  }
-
-  /**
-   * Helper function for parseQuery().
-   */
-  protected function parseWord($word) {
-    $num_new_scores = 0;
-    $num_valid_words = 0;
-    // Determine the scorewords of this word/phrase.
-    $split = explode(' ', $word);
-    foreach ($split as $s) {
-      $num = is_numeric($s);
-      if ($num || drupal_strlen($s) >= variable_get('minimum_word_size', 3)) {
-        if (!isset($this->words[$s])) {
-          $this->words[$s] = $s;
-          $num_new_scores++;
-        }
-        $num_valid_words++;
-      }
-    }
-    // Return matching snippet and number of added words.
-    return array($num_new_scores, $num_valid_words);
-  }
-
-  /**
-   * Executes the first pass query.
-   *
-   * This can either be done explicitly, so that additional scores and
-   * conditions can be applied to the second pass query, or implicitly by
-   * addScore() or execute().
-   *
-   * @return
-   *   TRUE if search items exist, FALSE if not.
-   */
-  public function executeFirstPass() {
-    $this->parseSearchExpression();
-
-    if (count($this->words) == 0) {
-      form_set_error('keys', format_plural(variable_get('minimum_word_size', 3), 'You must include at least one positive keyword with 1 character or more.', 'You must include at least one positive keyword with @count characters or more.'));
-      return FALSE;
-    }
-    if ($this->expressionsIgnored) {
-      drupal_set_message(t('Your search used too many AND/OR expressions. Only the first @count terms were included in this search.', array('@count' => variable_get('search_and_or_limit', 7))), 'warning');
-    }
-    $this->executedFirstPass = TRUE;
-
-    if (!empty($this->words)) {
-      $or = db_or();
-      foreach ($this->words as $word) {
-        $or->condition('i.word', $word);
-      }
-      $this->condition($or);
-    }
-    // Build query for keyword normalization.
-    $this->join('search_total', 't', 'i.word = t.word');
-    $this
-      ->condition('i.type', $this->type)
-      ->groupBy('i.type')
-      ->groupBy('i.sid')
-      ->having('COUNT(*) >= :matches', array(':matches' => $this->matches));
-
-    // Clone the query object to do the firstPass query;
-    $first = clone $this->query;
-
-    // For complex search queries, add the LIKE conditions to the first pass query.
-    if (!$this->simple) {
-      $first->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
-      $first->condition($this->conditions);
-    }
-
-    // Calculate maximum keyword relevance, to normalize it.
-    $first->addExpression('SUM(i.score * t.count)', 'calculated_score');
-    $this->normalize = $first
-      ->range(0, 1)
-      ->orderBy('calculated_score', 'DESC')
-      ->execute()
-      ->fetchField();
-
-    if ($this->normalize) {
-      return TRUE;
-    }
-    return FALSE;
-  }
-
-  /**
-   * Adds a custom score expression to the search query.
-   *
-   * Each score expression can optionally use a multiplier, and multiple
-   * expressions are combined.
-   *
-   * @param $score
-   *   The score expression.
-   * @param $arguments
-   *   Custom query arguments for that expression.
-   * @param $multiply
-   *   If set, the score is multiplied with that value. Search query ensures
-   *   that the search scores are still normalized.
-   */
-  public function addScore($score, $arguments = array(), $multiply = FALSE) {
-    if ($multiply) {
-      $i = count($this->multiply);
-      $score = "CAST(:multiply_$i AS DECIMAL) * COALESCE(( " . $score . "), 0) / CAST(:total_$i AS DECIMAL)";
-      $arguments[':multiply_' . $i] = $multiply;
-      $this->multiply[] = $multiply;
-    }
-
-    $this->scores[] = $score;
-    $this->scoresArguments += $arguments;
-
-    return $this;
-  }
-
-  /**
-   * Executes the search.
-   *
-   * If not already done, this executes the first pass query. Then the complex
-   * conditions are applied to the query including score expressions and
-   * ordering.
-   *
-   * @return
-   *   FALSE if the first pass query returned no results, and a database result
-   *   set if there were results.
-   */
-  public function execute()
-  {
-    if (!$this->executedFirstPass) {
-      $this->executeFirstPass();
-    }
-    if (!$this->normalize) {
-      return new StatementEmpty();
-    }
-
-    // Add conditions to query.
-    $this->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
-    $this->condition($this->conditions);
-
-    if (empty($this->scores)) {
-      // Add default score.
-      $this->addScore('i.relevance');
-    }
-
-    if (count($this->multiply)) {
-      // Add the total multiplicator as many times as requested to maintain
-      // normalization as far as possible.
-      $i = 0;
-      $sum = array_sum($this->multiply);
-      foreach ($this->multiply as $total) {
-        $this->scoresArguments[':total_' . $i] = $sum;
-        $i++;
-      }
-    }
-
-    // Replace i.relevance pseudo-field with the actual, normalized value.
-    $this->scores = str_replace('i.relevance', '(' . (1.0 / $this->normalize) . ' * i.score * t.count)', $this->scores);
-    // Convert scores to an expression.
-    $this->addExpression('SUM(' . implode(' + ', $this->scores) . ')', 'calculated_score', $this->scoresArguments);
-
-    if (count($this->getOrderBy()) == 0) {
-      // Add default order after adding the expression.
-      $this->orderBy('calculated_score', 'DESC');
-    }
-
-    // Add tag and useful metadata.
-    $this
-      ->addTag('search_' . $this->type)
-      ->addMetaData('normalize', $this->normalize)
-      ->fields('i', array('type', 'sid'));
-
-    return $this->query->execute();
-  }
-
-  /**
-   * Builds the default count query for SearchQuery.
-   *
-   * Since SearchQuery always uses GROUP BY, we can default to a subquery. We
-   * also add the same conditions as execute() because countQuery() is called
-   * first.
-   */
-  public function countQuery() {
-    // Clone the inner query.
-    $inner = clone $this->query;
-
-    // Add conditions to query.
-    $inner->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
-    $inner->condition($this->conditions);
-
-    // Remove existing fields and expressions, they are not needed for a count
-    // query.
-    $fields =& $inner->getFields();
-    $fields = array();
-    $expressions =& $inner->getExpressions();
-    $expressions = array();
-
-    // Add the sid as the only field and count them as a subquery.
-    $count = db_select($inner->fields('i', array('sid')), NULL, array('target' => 'slave'));
-
-    // Add the COUNT() expression.
-    $count->addExpression('COUNT(*)');
-
-    return $count;
-  }
-}
diff --git a/core/modules/search/search.info b/core/modules/search/search.info
index 1d47c96f2e1..a5a019ece1f 100644
--- a/core/modules/search/search.info
+++ b/core/modules/search/search.info
@@ -3,7 +3,6 @@ description = Enables site-wide keyword searching.
 package = Core
 version = VERSION
 core = 8.x
-files[] = search.extender.inc
 files[] = search.test
 configure = admin/config/search/settings
 stylesheets[all][] = search.theme.css
diff --git a/core/modules/search/search.test b/core/modules/search/search.test
index 8b67b0bdf8b..89444752e34 100644
--- a/core/modules/search/search.test
+++ b/core/modules/search/search.test
@@ -159,7 +159,7 @@ class SearchMatchTestCase extends SearchWebTestCase {
     );
     foreach ($queries as $query => $results) {
       $result = db_select('search_index', 'i')
-        ->extend('SearchQuery')
+        ->extend('Drupal\search\SearchQuery')
         ->searchExpression($query, SEARCH_TYPE)
         ->execute();
 
@@ -179,7 +179,7 @@ class SearchMatchTestCase extends SearchWebTestCase {
     );
     foreach ($queries as $query => $results) {
       $result = db_select('search_index', 'i')
-        ->extend('SearchQuery')
+        ->extend('Drupal\search\SearchQuery')
         ->searchExpression($query, SEARCH_TYPE_2)
         ->execute();
 
@@ -202,7 +202,7 @@ class SearchMatchTestCase extends SearchWebTestCase {
     );
     foreach ($queries as $query => $results) {
       $result = db_select('search_index', 'i')
-        ->extend('SearchQuery')
+        ->extend('Drupal\search\SearchQuery')
         ->searchExpression($query, SEARCH_TYPE_JPN)
         ->execute();