diff -u b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
--- b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
@@ -134,63 +134,65 @@
     $this->prepareQuery();
     $high_water_property = $this->migration->get('highWaterProperty');
 
-    // 2. If the map is joinable, join it. We will want to accept all rows
-    //    which are either not in the map, or marked in the map as NEEDS_UPDATE.
-    //    Note that if high water fields are in play, we want to accept all rows
-    //    above the high water mark in addition to those selected by the map
-    //    conditions, so we need to OR them together (but AND with any existing
-    //    conditions in the query). So, ultimately the SQL condition will look
-    //    like (original conditions) AND (map IS NULL OR map needs update
-    //      OR above high water).
-    $conditions = $this->query->orConditionGroup();
-    $condition_added = FALSE;
-    if ($this->mapJoinable()) {
-      // Build the join to the map table. Because the source key could have
-      // multiple fields, we need to build things up.
-      $count = 1;
-      $map_join = '';
-      $delimiter = '';
-      foreach ($this->getIds() as $field_name => $field_schema) {
-        if (isset($field_schema['alias'])) {
-          $field_name = $field_schema['alias'] . '.' . $field_name;
+    if (empty($this->configuration['idlist'])) {
+      // 1. If the map is joinable, join it. We will want to accept all rows
+      //    which are either not in the map, or marked in the map as NEEDS_UPDATE.
+      //    Note that if high water fields are in play, we want to accept all rows
+      //    above the high water mark in addition to those selected by the map
+      //    conditions, so we need to OR them together (but AND with any existing
+      //    conditions in the query). So, ultimately the SQL condition will look
+      //    like (original conditions) AND (map IS NULL OR map needs update
+      //      OR above high water).
+      $conditions = $this->query->orConditionGroup();
+      $condition_added = FALSE;
+      if ($this->mapJoinable()) {
+        // Build the join to the map table. Because the source key could have
+        // multiple fields, we need to build things up.
+        $count = 1;
+        $map_join = '';
+        $delimiter = '';
+        foreach ($this->getIds() as $field_name => $field_schema) {
+          if (isset($field_schema['alias'])) {
+            $field_name = $field_schema['alias'] . '.' . $field_name;
+          }
+          $map_join .= "$delimiter$field_name = map.sourceid" . $count++;
+          $delimiter = ' AND ';
         }
-        $map_join .= "$delimiter$field_name = map.sourceid" . $count++;
-        $delimiter = ' AND ';
-      }
 
-      $alias = $this->query->leftJoin($this->migration->getIdMap()->getQualifiedMapTableName(), 'map', $map_join);
-      $conditions->isNull($alias . '.sourceid1');
-      $conditions->condition($alias . '.source_row_status', MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
-      $condition_added = TRUE;
+        $alias = $this->query->leftJoin($this->migration->getIdMap()->getQualifiedMapTableName(), 'map', $map_join);
+        $conditions->isNull($alias . '.sourceid1');
+        $conditions->condition($alias . '.source_row_status', MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
+        $condition_added = TRUE;
 
-      // And as long as we have the map table, add its data to the row.
-      $n = count($this->getIds());
-      for ($count = 1; $count <= $n; $count++) {
-        $map_key = 'sourceid' . $count;
-        $this->query->addField($alias, $map_key, "migrate_map_$map_key");
-      }
-      if ($n = count($this->migration->get('destinationIds'))) {
+        // And as long as we have the map table, add its data to the row.
+        $n = count($this->getIds());
         for ($count = 1; $count <= $n; $count++) {
-          $map_key = 'destid' . $count++;
+          $map_key = 'sourceid' . $count;
           $this->query->addField($alias, $map_key, "migrate_map_$map_key");
         }
+        if ($n = count($this->migration->get('destinationIds'))) {
+          for ($count = 1; $count <= $n; $count++) {
+            $map_key = 'destid' . $count++;
+            $this->query->addField($alias, $map_key, "migrate_map_$map_key");
+          }
+        }
+        $this->query->addField($alias, 'source_row_status', 'migrate_map_source_row_status');
       }
-      $this->query->addField($alias, 'source_row_status', 'migrate_map_source_row_status');
-    }
-    // 3. If we are using high water marks, also include rows above the mark.
-    //    But, include all rows if the high water mark is not set.
-    if (isset($high_water_property['name']) && ($high_water = $this->migration->getHighWater()) !== '') {
-      if (isset($high_water_property['alias'])) {
-        $high_water = $high_water_property['alias'] . '.' . $high_water_property['name'];
+      // 2. If we are using high water marks, also include rows above the mark.
+      //    But, include all rows if the high water mark is not set.
+      if (isset($high_water_property['name']) && ($high_water = $this->migration->getHighWater()) !== '') {
+        if (isset($high_water_property['alias'])) {
+          $high_water = $high_water_property['alias'] . '.' . $high_water_property['name'];
+        }
+        else {
+          $high_water = $high_water_property['name'];
+        }
+        $conditions->condition($high_water, $high_water, '>');
+        $condition_added = TRUE;
       }
-      else {
-        $high_water = $high_water_property['name'];
+      if ($condition_added) {
+        $this->query->condition($conditions);
       }
-      $conditions->condition($high_water, $high_water, '>');
-      $condition_added = TRUE;
-    }
-    if ($condition_added) {
-      $this->query->condition($conditions);
     }
 
     return new \IteratorIterator($this->query->execute());