Improve performance of relationship discovery when adding OGR dataset…

… with many layers (fixes #53525)
qgis · Jul 19, 2023 · 567fb82 · 567fb82
1 parent c121ce3
commit 567fb82
Showing 1 changed file with 49 additions and 5 deletions.
diff --git a/src/app/layers/qgsapplayerhandling.cpp b/src/app/layers/qgsapplayerhandling.cpp
@@ -216,6 +216,10 @@ void QgsAppLayerHandling::addSortedLayersToLegend( QList<QgsMapLayer *> &layers
 
 void QgsAppLayerHandling::postProcessAddedLayers( const QList<QgsMapLayer *> &layers )
 {
+  std::map<QString, int> mapPathToReferenceCount;
+  std::map<QString, QList< QgsWeakRelation >> mapPathToRelations;
+
+  QgsProviderMetadata *ogrProviderMetadata = QgsProviderRegistry::instance()->providerMetadata( QStringLiteral( "ogr" ) );
   for ( QgsMapLayer *layer : layers )
   {
     switch ( layer->type() )
@@ -227,15 +231,55 @@ void QgsAppLayerHandling::postProcessAddedLayers( const QList<QgsMapLayer *> &la
         // try to automatically load related tables for OGR layers
         if ( vl->providerType() == QLatin1String( "ogr" ) )
         {
+          const QVariantMap uriParts = ogrProviderMetadata->decodeUri( layer->source() );
+          const QString layerName = uriParts.value( QStringLiteral( "layerName" ) ).toString();
+          if ( layerName.isEmpty() )
+            continue;
+
+          // If this dataset is read more than once, collect and store all its
+          // relationships
+          const QString path = uriParts.value( QStringLiteral( "path" ) ).toString();
+          if ( ++mapPathToReferenceCount[path] == 2 )
+          {
+            std::unique_ptr< QgsAbstractDatabaseProviderConnection > conn { QgsMapLayerUtils::databaseConnection( vl ) };
+            if ( conn && ( conn->capabilities() & QgsAbstractDatabaseProviderConnection::Capability::RetrieveRelationships ) )
+            {
+              const QList< QgsWeakRelation > relations = conn->relationships( QString(), QString() );
+              mapPathToRelations[path] = relations;
+            }
+          }
+
+          // If this is a OGR dataset referenced by several layers, do not
+          // open a new connection on it but reuse the results of the first pass
+          auto iterMapPathToRelations = mapPathToRelations.find( path );
+          if ( iterMapPathToRelations != mapPathToRelations.end() )
+          {
+            if ( !iterMapPathToRelations->second.isEmpty() )
+            {
+              QList< QgsWeakRelation > layerRelations;
+              for ( const QgsWeakRelation &rel : std::as_const( iterMapPathToRelations->second ) )
+              {
+                const QVariantMap leftParts = ogrProviderMetadata->decodeUri( rel.referencedLayerSource() );
+                const QString leftTableName = leftParts.value( QStringLiteral( "layerName" ) ).toString();
+                if ( leftTableName == layerName )
+                {
+                  layerRelations << rel;
+                }
+              }
+              if ( !layerRelations.isEmpty() )
+              {
+                vl->setWeakRelations( layerRelations );
+                resolveVectorLayerDependencies( vl, QgsMapLayer::StyleCategory::Relations, QgsVectorLayerRef::MatchType::Source, DependencyFlag::LoadAllRelationships | DependencyFlag::SilentLoad );
+                resolveVectorLayerWeakRelations( vl, QgsVectorLayerRef::MatchType::Source, true );
+              }
+            }
+            continue;
+          }
+
           // first need to create weak relations!!
           std::unique_ptr< QgsAbstractDatabaseProviderConnection > conn { QgsMapLayerUtils::databaseConnection( vl ) };
           if ( conn && ( conn->capabilities() & QgsAbstractDatabaseProviderConnection::Capability::RetrieveRelationships ) )
           {
-            const QVariantMap uriParts = QgsProviderRegistry::instance()->decodeUri( layer->providerType(), layer->source() );
-            const QString layerName = uriParts.value( QStringLiteral( "layerName" ) ).toString();
-            if ( layerName.isEmpty() )
-              continue;
-
             const QList< QgsWeakRelation > relations = conn->relationships( QString(), layerName );
             if ( !relations.isEmpty() )
             {