migrations/d7_metatag_field_instance.yml           |  7 +---
 .../migrate/source/d7/MetatagFieldDeriver.php      | 19 +++------
 .../migrate/source/d7/MetatagFieldInstance.php     | 45 +++++++++++++++++++++-
 .../source/d7/MetatagFieldInstanceDeriver.php      | 21 +++++-----
 4 files changed, 63 insertions(+), 29 deletions(-)

diff --git a/migrations/d7_metatag_field_instance.yml b/migrations/d7_metatag_field_instance.yml
index 35a500d..70d1d78 100644
--- a/migrations/d7_metatag_field_instance.yml
+++ b/migrations/d7_metatag_field_instance.yml
@@ -26,9 +26,4 @@ migration_dependencies:
   required:
     # The base field migration is required before this migration can run.
     - d7_metatag_field
-
-    # @todo Is this accurate? Does it really need the vocabulary migration, or
-    # is it more precautionary, that it *might* be needed so it might as well be
-    # executed first?
-    - d7_node_type
-    - d7_taxonomy_vocabulary
+    # Relevant required dependencies are added in \Drupal\metatag\Migrate\MigrationPluginAlterer.
diff --git a/src/Plugin/migrate/source/d7/MetatagFieldDeriver.php b/src/Plugin/migrate/source/d7/MetatagFieldDeriver.php
index 0d8fa5a..294dc2b 100644
--- a/src/Plugin/migrate/source/d7/MetatagFieldDeriver.php
+++ b/src/Plugin/migrate/source/d7/MetatagFieldDeriver.php
@@ -23,17 +23,6 @@ class MetatagFieldDeriver extends DeriverBase implements ContainerDeriverInterfa
   use MigrationConfigurationTrait;
   use StringTranslationTrait;
 
-  /**
-   * Required entity type DB tables, keyed by the entity type ID.
-   *
-   * @var string[][]
-   */
-  protected $supportedEntityTypesTables = [
-    'node' => ['node', 'node_type'],
-    'taxonomy_term' => ['taxonomy_term_data', 'taxonomy_vocabulary'],
-    'user' => [],
-  ];
-
   /**
    * The entity type manager.
    *
@@ -42,7 +31,7 @@ class MetatagFieldDeriver extends DeriverBase implements ContainerDeriverInterfa
   protected $entityTypeManager;
 
   /**
-   * Constructs a PathRedirectDeriver instance.
+   * Constructs a MetatagFieldDeriver instance.
    *
    * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
    *   The entity type manager.
@@ -82,6 +71,11 @@ class MetatagFieldDeriver extends DeriverBase implements ContainerDeriverInterfa
       ->execute()
       ->fetchAllKeyed(0, 0);
     foreach ($entity_type_ids as $entity_type_id) {
+      // Skip if the entity type is missing.
+      if (!($entity_type_definition = $this->entityTypeManager->getDefinition($entity_type_id, FALSE))) {
+        continue;
+      }
+
       $this->derivatives[$entity_type_id] = $base_plugin_definition;
       $this->derivatives[$entity_type_id]['source']['entity_type'] = $entity_type_id;
       $this->derivatives[$entity_type_id]['source']['entity_type_id'] = $entity_type_id;
@@ -90,7 +84,6 @@ class MetatagFieldDeriver extends DeriverBase implements ContainerDeriverInterfa
         '@type' => $this->entityTypeManager->getDefinition($entity_type_id)->getPluralLabel(),
       ]);
     }
-    $this->derivatives['other'] = $base_plugin_definition;
 
     return $this->derivatives;
   }
diff --git a/src/Plugin/migrate/source/d7/MetatagFieldInstance.php b/src/Plugin/migrate/source/d7/MetatagFieldInstance.php
index 217f49c..000f6b5 100644
--- a/src/Plugin/migrate/source/d7/MetatagFieldInstance.php
+++ b/src/Plugin/migrate/source/d7/MetatagFieldInstance.php
@@ -48,9 +48,44 @@ class MetatagFieldInstance extends DrupalSqlBase {
    * {@inheritdoc}
    */
   public function query() {
-    return $this->select('metatag', 'm')
+    $base_query = $this->select('metatag', 'm')
       ->fields('m', ['entity_type'])
       ->groupBy('entity_type');
+
+    if (isset($this->configuration['entity_type_id'])) {
+      $entity_type_id = $this->configuration['entity_type_id'];
+      $base_query->condition('m.entity_type', $entity_type_id);
+
+      if (isset($this->configuration['bundle'])) {
+        $bundle = $this->configuration['bundle'];
+        switch ($entity_type_id) {
+          case 'node':
+            // We want to get a per-node-type metatag migration. So we inner join
+            // the base query on node table based on the parsed node ID.
+            $base_query->join('node', 'n', "n.nid = m.entity_id");
+            $base_query->condition('n.type', $bundle);
+            $base_query->addField('n', 'type', 'bundle');
+            $base_query->groupBy('bundle');
+            break;
+
+          case 'taxonomy_term':
+            // Join the taxonomy term data table to the base query; based on
+            // the parsed taxonomy term ID.
+            $base_query->join('taxonomy_term_data', 'ttd', "ttd.tid = m.entity_id");
+            $base_query->fields('ttd', ['vid']);
+            // Since the "taxonomy_term_data" table contains only the taxonomy
+            // vocabulary ID, but not the vocabulary name, we have to inner
+            // join the "taxonomy_vocabulary" table as well.
+            $base_query->join('taxonomy_vocabulary', 'tv', 'ttd.vid = tv.vid');
+            $base_query->condition('tv.machine_name', $bundle);
+            $base_query->addField('tv', 'machine_name', 'bundle');
+            $base_query->groupBy('bundle');
+            break;
+        }
+      }
+    }
+
+    return $base_query;
   }
 
   /**
@@ -69,6 +104,14 @@ class MetatagFieldInstance extends DrupalSqlBase {
   public function initializeIterator() {
     $bundles = [];
     foreach (parent::initializeIterator() as $instance) {
+      // For entity types for which we support creating derivatives, do not
+      // retrieve the bundles using the D8|9 entity type bundle info service,
+      // because then we will end up creating meta tag fields even for bundles
+      // that do not use meta tags.
+      if (isset($instance['bundle'])) {
+        $bundles[] = $instance;
+        continue;
+      }
       $bundle_info = $this->entityTypeBundleInfo
         ->getBundleInfo($instance['entity_type']);
       foreach (array_keys($bundle_info) as $bundle) {
diff --git a/src/Plugin/migrate/source/d7/MetatagFieldInstanceDeriver.php b/src/Plugin/migrate/source/d7/MetatagFieldInstanceDeriver.php
index 2015ca1..0b73988 100644
--- a/src/Plugin/migrate/source/d7/MetatagFieldInstanceDeriver.php
+++ b/src/Plugin/migrate/source/d7/MetatagFieldInstanceDeriver.php
@@ -89,12 +89,17 @@ class MetatagFieldInstanceDeriver extends DeriverBase implements ContainerDerive
       $base_query = $source->getDatabase()->select('metatag', 'm');
       $base_query->condition('m.entity_type', $entity_type_id);
 
+      // If there are no metatags for this entity type, no derivatives needed.
+      $metatag_count = (int) (clone $base_query)->countQuery()->execute()->fetchField();
+      if ($metatag_count === 0) {
+        continue;
+      }
+
       $metatags_grouped_by_bundle = [];
       switch ($entity_type_id) {
         case 'node':
-          // We want to get a per-node-type path redirect migration. So we
-          // inner join the base query on node table based on the parsed
-          // node ID.
+          // We want to get a per-node-type metatag migration. So we inner join
+          // the base query on node table based on the parsed node ID.
           $base_query->join('node', 'n', "n.nid = m.entity_id");
           $base_query->fields('n', ['type']);
           // We'll need the "human" name of the node type.
@@ -103,7 +108,7 @@ class MetatagFieldInstanceDeriver extends DeriverBase implements ContainerDerive
           $base_query->groupBy('n.type');
           $base_query->groupBy('nt.name');
 
-          // Get every node-related path redirect ID, grouped by node type.
+          // Get every node-related metatag, grouped by node type.
           $rows = $base_query->execute()->fetchAllAssoc('type');
           $metatags_grouped_by_bundle = array_reduce($rows, function (array $carry, $row) {
             $carry[$row->type] = $row->name;
@@ -116,7 +121,6 @@ class MetatagFieldInstanceDeriver extends DeriverBase implements ContainerDerive
           // Join the taxonomy term data table to the base query; based on
           // the parsed taxonomy term ID.
           $base_query->join('taxonomy_term_data', 'ttd', "ttd.tid = m.entity_id");
-          $foo = '';
           $base_query->fields('ttd', ['vid']);
           // Since the "taxonomy_term_data" table contains only the taxonomy
           // vocabulary ID, but not the vocabulary name, we have to inner
@@ -127,7 +131,7 @@ class MetatagFieldInstanceDeriver extends DeriverBase implements ContainerDerive
           $base_query->groupBy('tv.machine_name');
           $base_query->groupBy('tv.name');
 
-          // Get all of the path redirects whose destination is a taxonomy
+          // Get all of the metatags whose destination is a taxonomy
           // term URL.
           $rows = $base_query->execute()->fetchAllAssoc('machine_name');
           $metatags_grouped_by_bundle = array_reduce($rows, function (array $carry, $row) {
@@ -140,7 +144,7 @@ class MetatagFieldInstanceDeriver extends DeriverBase implements ContainerDerive
 
       // If we have per-bundle results for a content entity type, we are
       // able to derive migrations per entity type and bundle.
-      // Dependency metadata is added im redirect_migration_plugins_alter().
+      // Dependency metadata is added im \Drupal\metatag\Migrate\MigrationPluginAlterer::alterMigrationPlugins().
       if (!empty($metatags_grouped_by_bundle)) {
         foreach ($metatags_grouped_by_bundle as $bundle_id => $bundle_label) {
           $derivative_id = "$entity_type_id:$bundle_id";
@@ -156,7 +160,7 @@ class MetatagFieldInstanceDeriver extends DeriverBase implements ContainerDerive
         }
       }
       // If we don't have per-bundle results, we will derive only a
-      // per-entity-type path redirect migration.
+      // per-entity-type metatag migration.
       else {
         $this->derivatives[$entity_type_id] = $base_plugin_definition;
         $this->derivatives[$entity_type_id]['source']['entity_type_id'] = $entity_type_id;
@@ -166,7 +170,6 @@ class MetatagFieldInstanceDeriver extends DeriverBase implements ContainerDerive
         ]);
       }
     }
-    $this->derivatives['other'] = $base_plugin_definition;
 
     return $this->derivatives;
   }