--- a/CMakeLists.txt	Sat Jan 05 12:17:30 2019 +0100
+++ b/CMakeLists.txt	Sat Jan 05 15:08:53 2019 +0100
@@ -73,6 +73,7 @@
   OrthancServer/SQLiteDatabaseWrapper.cpp
   OrthancServer/Search/Compatibility/DatabaseLookup.cpp
   OrthancServer/Search/Compatibility/ICreateInstance.cpp
+  OrthancServer/Search/Compatibility/IGetChildrenMetadata.cpp
   OrthancServer/Search/Compatibility/ILookupResources.cpp
   OrthancServer/Search/Compatibility/SetOfResources.cpp
   OrthancServer/Search/DatabaseConstraint.cpp

--- a/OrthancServer/IDatabaseWrapper.h	Sat Jan 05 12:17:30 2019 +0100
+++ b/OrthancServer/IDatabaseWrapper.h	Sat Jan 05 15:08:53 2019 +0100
@@ -237,5 +237,9 @@
     // them. However, some metadata might be already existing, and
     // have to be overwritten.
     virtual void SetResourcesContent(const ResourcesContent& content) = 0;
+
+    virtual void GetChildrenMetadata(std::list<std::string>& target,
+                                     int64_t resourceId,
+                                     MetadataType metadata) = 0;
   };
 }

--- a/OrthancServer/SQLiteDatabaseWrapper.h	Sat Jan 05 12:17:30 2019 +0100
+++ b/OrthancServer/SQLiteDatabaseWrapper.h	Sat Jan 05 15:08:53 2019 +0100
@@ -37,6 +37,7 @@
 
 #include "../Core/SQLite/Connection.h"
 #include "Search/Compatibility/ICreateInstance.h"
+#include "Search/Compatibility/IGetChildrenMetadata.h"
 #include "Search/Compatibility/ISetResourcesContent.h"
 #include "ServerToolbox.h"
 
@@ -55,6 +56,7 @@
   class SQLiteDatabaseWrapper :
     public IDatabaseWrapper,
     public Compatibility::ICreateInstance,
+    public Compatibility::IGetChildrenMetadata,
     public Compatibility::ISetResourcesContent
   {
   private:
@@ -332,15 +334,25 @@
                                 const std::string& patient,
                                 const std::string& study,
                                 const std::string& series,
-                                const std::string& instance)  ORTHANC_OVERRIDE
+                                const std::string& instance)
+      ORTHANC_OVERRIDE
     {
       return ICreateInstance::Apply
-        (*this, *this, result, instanceId, patient, study, series, instance);
+        (*this, result, instanceId, patient, study, series, instance);
     }
 
-    virtual void SetResourcesContent(const Orthanc::ResourcesContent& content)  ORTHANC_OVERRIDE
+    virtual void SetResourcesContent(const Orthanc::ResourcesContent& content)
+      ORTHANC_OVERRIDE
     {
       ISetResourcesContent::Apply(*this, content);
     }
+
+    virtual void GetChildrenMetadata(std::list<std::string>& target,
+                                     int64_t resourceId,
+                                     MetadataType metadata)
+      ORTHANC_OVERRIDE
+    {
+      IGetChildrenMetadata::Apply(*this, target, resourceId, metadata);
+    }
   };
 }

--- a/OrthancServer/Search/Compatibility/ICreateInstance.cpp	Sat Jan 05 12:17:30 2019 +0100
+++ b/OrthancServer/Search/Compatibility/ICreateInstance.cpp	Sat Jan 05 15:08:53 2019 +0100
@@ -40,8 +40,7 @@
 {
   namespace Compatibility
   {
-    bool ICreateInstance::Apply(ICreateInstance& compatibility,
-                                IDatabaseWrapper& database,
+    bool ICreateInstance::Apply(ICreateInstance& database,
                                 IDatabaseWrapper::CreateInstanceResult& result,
                                 int64_t& instanceId,
                                 const std::string& hashPatient,
@@ -62,7 +61,7 @@
         }
       }
 
-      instanceId = compatibility.CreateResource(hashInstance, ResourceType_Instance);
+      instanceId = database.CreateResource(hashInstance, ResourceType_Instance);
 
       result.isNewPatient_ = false;
       result.isNewStudy_ = false;
@@ -116,32 +115,32 @@
       // Create the series if needed
       if (result.isNewSeries_)
       {
-        result.seriesId_ = compatibility.CreateResource(hashSeries, ResourceType_Series);
+        result.seriesId_ = database.CreateResource(hashSeries, ResourceType_Series);
       }
 
       // Create the study if needed
       if (result.isNewStudy_)
       {
-        result.studyId_ = compatibility.CreateResource(hashStudy, ResourceType_Study);
+        result.studyId_ = database.CreateResource(hashStudy, ResourceType_Study);
       }
 
       // Create the patient if needed
       if (result.isNewPatient_)
       {
-        result.patientId_ = compatibility.CreateResource(hashPatient, ResourceType_Patient);
+        result.patientId_ = database.CreateResource(hashPatient, ResourceType_Patient);
       }
 
       // Create the parent-to-child links
-      compatibility.AttachChild(result.seriesId_, instanceId);
+      database.AttachChild(result.seriesId_, instanceId);
 
       if (result.isNewSeries_)
       {
-        compatibility.AttachChild(result.studyId_, result.seriesId_);
+        database.AttachChild(result.studyId_, result.seriesId_);
       }
 
       if (result.isNewStudy_)
       {
-        compatibility.AttachChild(result.patientId_, result.studyId_);
+        database.AttachChild(result.patientId_, result.studyId_);
       }
 
       // Sanity checks

--- a/OrthancServer/Search/Compatibility/ICreateInstance.h	Sat Jan 05 12:17:30 2019 +0100
+++ b/OrthancServer/Search/Compatibility/ICreateInstance.h	Sat Jan 05 15:08:53 2019 +0100
@@ -42,14 +42,17 @@
     class ICreateInstance : public boost::noncopyable
     {
     public:
+      virtual bool LookupResource(int64_t& id,
+                                  ResourceType& type,
+                                  const std::string& publicId) = 0;
+
       virtual int64_t CreateResource(const std::string& publicId,
                                      ResourceType type) = 0;
 
       virtual void AttachChild(int64_t parent,
                                int64_t child) = 0;
       
-      static bool Apply(ICreateInstance& compatibility,
-                        IDatabaseWrapper& database,
+      static bool Apply(ICreateInstance& database,
                         IDatabaseWrapper::CreateInstanceResult& result,
                         int64_t& instanceId,
                         const std::string& patient,

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancServer/Search/Compatibility/IGetChildrenMetadata.cpp	Sat Jan 05 15:08:53 2019 +0100
@@ -0,0 +1,67 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders of this
+ * program give permission to link the code of its release with the
+ * OpenSSL project's "OpenSSL" library (or with modified versions of it
+ * that use the same license as the "OpenSSL" library), and distribute
+ * the linked executables. You must obey the GNU General Public License
+ * in all respects for all of the code used other than "OpenSSL". If you
+ * modify file(s) with this exception, you may extend this exception to
+ * your version of the file(s), but you are not obligated to do so. If
+ * you do not wish to do so, delete this exception statement from your
+ * version. If you delete this exception statement from all source files
+ * in the program, then also delete it here.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "../../PrecompiledHeadersServer.h"
+#include "IGetChildrenMetadata.h"
+
+namespace Orthanc
+{
+  namespace Compatibility
+  {
+    void IGetChildrenMetadata::Apply(IGetChildrenMetadata& database,
+                                     std::list<std::string>& target,
+                                     int64_t resourceId,
+                                     MetadataType metadata)
+    {
+      // This function comes from an optimization of
+      // "ServerIndex::GetSeriesStatus()" in Orthanc <= 1.5.1
+      // Loop over the instances of this series
+
+      target.clear();
+      
+      std::list<int64_t> children;
+      database.GetChildrenInternalId(children, resourceId);
+
+      std::set<int64_t> instances;
+      for (std::list<int64_t>::const_iterator 
+             it = children.begin(); it != children.end(); ++it)
+      {
+        std::string value;
+        if (database.LookupMetadata(value, *it, metadata))
+        {
+          target.push_back(value);
+        }
+      }
+    }
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancServer/Search/Compatibility/IGetChildrenMetadata.h	Sat Jan 05 15:08:53 2019 +0100
@@ -0,0 +1,61 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders of this
+ * program give permission to link the code of its release with the
+ * OpenSSL project's "OpenSSL" library (or with modified versions of it
+ * that use the same license as the "OpenSSL" library), and distribute
+ * the linked executables. You must obey the GNU General Public License
+ * in all respects for all of the code used other than "OpenSSL". If you
+ * modify file(s) with this exception, you may extend this exception to
+ * your version of the file(s), but you are not obligated to do so. If
+ * you do not wish to do so, delete this exception statement from your
+ * version. If you delete this exception statement from all source files
+ * in the program, then also delete it here.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#pragma once
+
+#include "../../ServerEnumerations.h"
+
+#include <boost/noncopyable.hpp>
+#include <list>
+
+namespace Orthanc
+{
+  namespace Compatibility
+  {
+    class IGetChildrenMetadata : public boost::noncopyable
+    {
+    public:
+      virtual void GetChildrenInternalId(std::list<int64_t>& target,
+                                         int64_t id) = 0;
+
+      virtual bool LookupMetadata(std::string& target,
+                                  int64_t id,
+                                  MetadataType type) = 0;
+
+      static void Apply(IGetChildrenMetadata& database,
+                        std::list<std::string>& target,
+                        int64_t resourceId,
+                        MetadataType metadata);
+    };
+  }
+}

--- a/OrthancServer/ServerIndex.cpp	Sat Jan 05 12:17:30 2019 +0100
+++ b/OrthancServer/ServerIndex.cpp	Sat Jan 05 15:08:53 2019 +0100
@@ -993,21 +993,25 @@
   SeriesStatus ServerIndex::GetSeriesStatus(int64_t id,
                                             int64_t expectedNumberOfInstances)
   {
-    // Loop over the instances of this series
-    std::list<int64_t> children;
-    db_.GetChildrenInternalId(children, id);
+    std::list<std::string> values;
+    db_.GetChildrenMetadata(values, id, MetadataType_Instance_IndexInSeries);
 
     std::set<int64_t> instances;
-    for (std::list<int64_t>::const_iterator 
-           it = children.begin(); it != children.end(); ++it)
+
+    for (std::list<std::string>::const_iterator
+           it = values.begin(); it != values.end(); ++it)
     {
-      // Get the index of this instance in the series
       int64_t index;
-      if (!GetMetadataAsInteger(index, *it, MetadataType_Instance_IndexInSeries))
+
+      try
+      {
+        index = boost::lexical_cast<int64_t>(*it);
+      }
+      catch (boost::bad_lexical_cast&)
       {
         return SeriesStatus_Unknown;
       }
-
+      
       if (!(index > 0 && index <= expectedNumberOfInstances))
       {
         // Out-of-range instance index
@@ -1200,9 +1204,13 @@
 
         int64_t i;
         if (GetMetadataAsInteger(i, id, MetadataType_Instance_IndexInSeries))
+        {
           result["IndexInSeries"] = static_cast<int>(i);
+        }
         else
+        {
           result["IndexInSeries"] = Json::nullValue;
+        }
 
         break;
       }

--- a/Plugins/Engine/OrthancPluginDatabase.cpp	Sat Jan 05 12:17:30 2019 +0100
+++ b/Plugins/Engine/OrthancPluginDatabase.cpp	Sat Jan 05 15:08:53 2019 +0100
@@ -1201,7 +1201,7 @@
     {
       // Fallback to compatibility mode
       return ICreateInstance::Apply
-        (*this, *this, result, instanceId, patient, study, series, instance);
+        (*this, result, instanceId, patient, study, series, instance);
     }
     else
     {
@@ -1306,4 +1306,14 @@
                      (metadata.empty() ? NULL : &metadata[0])));
     }
   }
+
+
+
+  void OrthancPluginDatabase::GetChildrenMetadata(std::list<std::string>& target,
+                                                  int64_t resourceId,
+                                                  MetadataType metadata)
+  {
+    // TODO
+    IGetChildrenMetadata::Apply(*this, target, resourceId, metadata);
+  }
 }

--- a/Plugins/Engine/OrthancPluginDatabase.h	Sat Jan 05 12:17:30 2019 +0100
+++ b/Plugins/Engine/OrthancPluginDatabase.h	Sat Jan 05 15:08:53 2019 +0100
@@ -36,9 +36,10 @@
 #if ORTHANC_ENABLE_PLUGINS == 1
 
 #include "../../Core/SharedLibrary.h"
+#include "../../OrthancServer/Search/Compatibility/ICreateInstance.h"
+#include "../../OrthancServer/Search/Compatibility/IGetChildrenMetadata.h"
 #include "../../OrthancServer/Search/Compatibility/ILookupResources.h"
 #include "../../OrthancServer/Search/Compatibility/ISetResourcesContent.h"
-#include "../../OrthancServer/Search/Compatibility/ICreateInstance.h"
 #include "../Include/orthanc/OrthancCDatabasePlugin.h"
 #include "PluginsErrorDictionary.h"
 
@@ -46,9 +47,10 @@
 {
   class OrthancPluginDatabase :
     public IDatabaseWrapper,
+    public Compatibility::ICreateInstance,
+    public Compatibility::IGetChildrenMetadata,
     public Compatibility::ILookupResources,
-    public Compatibility::ISetResourcesContent,
-    public Compatibility::ICreateInstance
+    public Compatibility::ISetResourcesContent
   {
   private:
     class Transaction;
@@ -353,6 +355,11 @@
 
     virtual void SetResourcesContent(const Orthanc::ResourcesContent& content)
       ORTHANC_OVERRIDE;
+
+    virtual void GetChildrenMetadata(std::list<std::string>& target,
+                                     int64_t resourceId,
+                                     MetadataType metadata)
+      ORTHANC_OVERRIDE;
   };
 }