Speed up spatialite provider

No need to iterate over all the features in the datasource only to find out that there is no feature which is not in an empty list of feature ids.
qgis · Oct 24, 2017 · 86b28ff · 86b28ff
1 parent 269f751
commit 86b28ff
Showing 1 changed file with 66 additions and 60 deletions.
diff --git a/src/providers/spatialite/qgsspatialitefeatureiterator.cpp b/src/providers/spatialite/qgsspatialitefeatureiterator.cpp
@@ -53,7 +53,7 @@ QgsSpatiaLiteFeatureIterator::QgsSpatiaLiteFeatureIterator( QgsSpatiaLiteFeature
   catch ( QgsCsException & )
   {
     // can't reproject mFilterRect
-    mClosed = true;
+    close();
     return;
   }
 
@@ -90,10 +90,13 @@ QgsSpatiaLiteFeatureIterator::QgsSpatiaLiteFeatureIterator( QgsSpatiaLiteFeature
   }
   else if ( request.filterType() == QgsFeatureRequest::FilterFids )
   {
-    whereClause = whereClauseFids();
+    if ( request.filterFids().isEmpty() )
-    if ( ! whereClause.isEmpty() )
     {
-      whereClauses.append( whereClause );
+      close();
+    }
+    else
+    {
+      whereClauses.append( whereClauseFids() );
     }
   }
   //IMPORTANT - this MUST be the last clause added!
@@ -144,77 +147,80 @@ QgsSpatiaLiteFeatureIterator::QgsSpatiaLiteFeatureIterator( QgsSpatiaLiteFeature
     }
   }
 
-  whereClause = whereClauses.join( QStringLiteral( " AND " ) );
+  if ( !mClosed )
+  {
+    whereClause = whereClauses.join( QStringLiteral( " AND " ) );
 
-  // Setup the order by
+    // Setup the order by
-  QStringList orderByParts;
+    QStringList orderByParts;
 
-  mOrderByCompiled = true;
+    mOrderByCompiled = true;
 
-  if ( QgsSettings().value( QStringLiteral( "qgis/compileExpressions" ), true ).toBool() )
+    if ( QgsSettings().value( QStringLiteral( "qgis/compileExpressions" ), true ).toBool() )
-  {
-    Q_FOREACH ( const QgsFeatureRequest::OrderByClause &clause, request.orderBy() )
     {
-      QgsSQLiteExpressionCompiler compiler = QgsSQLiteExpressionCompiler( source->mFields );
+      Q_FOREACH ( const QgsFeatureRequest::OrderByClause &clause, request.orderBy() )
-      QgsExpression expression = clause.expression();
-      if ( compiler.compile( &expression ) == QgsSqlExpressionCompiler::Complete )
       {
-        QString part;
+        QgsSQLiteExpressionCompiler compiler = QgsSQLiteExpressionCompiler( source->mFields );
-        part = compiler.result();
+        QgsExpression expression = clause.expression();
+        if ( compiler.compile( &expression ) == QgsSqlExpressionCompiler::Complete )
+        {
+          QString part;
+          part = compiler.result();
 
-        if ( clause.nullsFirst() )
+          if ( clause.nullsFirst() )
-          orderByParts << QStringLiteral( "%1 IS NOT NULL" ).arg( part );
+            orderByParts << QStringLiteral( "%1 IS NOT NULL" ).arg( part );
-        else
+          else
-          orderByParts << QStringLiteral( "%1 IS NULL" ).arg( part );
+            orderByParts << QStringLiteral( "%1 IS NULL" ).arg( part );
 
-        part += clause.ascending() ? " COLLATE NOCASE ASC" : " COLLATE NOCASE DESC";
+          part += clause.ascending() ? " COLLATE NOCASE ASC" : " COLLATE NOCASE DESC";
-        orderByParts << part;
+          orderByParts << part;
-      }
+        }
-      else
+        else
-      {
+        {
-        // Bail out on first non-complete compilation.
+          // Bail out on first non-complete compilation.
-        // Most important clauses at the beginning of the list
+          // Most important clauses at the beginning of the list
-        // will still be sent and used to pre-sort so the local
+          // will still be sent and used to pre-sort so the local
-        // CPU can use its cycles for fine-tuning.
+          // CPU can use its cycles for fine-tuning.
-        mOrderByCompiled = false;
+          mOrderByCompiled = false;
-        break;
+          break;
+        }
       }
     }
-  }
+    else
-  else
+    {
-  {
+      mOrderByCompiled = false;
-    mOrderByCompiled = false;
+    }
-  }
 
-  if ( !mOrderByCompiled )
+    if ( !mOrderByCompiled )
-    limitAtProvider = false;
+      limitAtProvider = false;
 
-  // also need attributes required by order by
+    // also need attributes required by order by
-  if ( !mOrderByCompiled && mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes && !mRequest.orderBy().isEmpty() )
+    if ( !mOrderByCompiled && mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes && !mRequest.orderBy().isEmpty() )
-  {
-    QSet<int> attributeIndexes;
-    Q_FOREACH ( const QString &attr, mRequest.orderBy().usedAttributes() )
     {
-      attributeIndexes << mSource->mFields.lookupField( attr );
+      QSet<int> attributeIndexes;
+      Q_FOREACH ( const QString &attr, mRequest.orderBy().usedAttributes() )
+      {
+        attributeIndexes << mSource->mFields.lookupField( attr );
+      }
+      attributeIndexes += mRequest.subsetOfAttributes().toSet();
+      mRequest.setSubsetOfAttributes( attributeIndexes.toList() );
     }
-    attributeIndexes += mRequest.subsetOfAttributes().toSet();
-    mRequest.setSubsetOfAttributes( attributeIndexes.toList() );
-  }
 
-  // preparing the SQL statement
+    // preparing the SQL statement
-  bool success = prepareStatement( whereClause, limitAtProvider ? mRequest.limit() : -1, orderByParts.join( QStringLiteral( "," ) ) );
+    bool success = prepareStatement( whereClause, limitAtProvider ? mRequest.limit() : -1, orderByParts.join( QStringLiteral( "," ) ) );
-  if ( !success && useFallbackWhereClause )
+    if ( !success && useFallbackWhereClause )
-  {
+    {
-    //try with the fallback where clause, e.g., for cases when using compiled expression failed to prepare
+      //try with the fallback where clause, e.g., for cases when using compiled expression failed to prepare
-    mExpressionCompiled = false;
+      mExpressionCompiled = false;
-    success = prepareStatement( fallbackWhereClause, -1, orderByParts.join( QStringLiteral( "," ) ) );
+      success = prepareStatement( fallbackWhereClause, -1, orderByParts.join( QStringLiteral( "," ) ) );
-  }
+    }
 
-  if ( !success )
+    if ( !success )
-  {
+    {
-    // some error occurred
+      // some error occurred
-    sqliteStatement = nullptr;
+      sqliteStatement = nullptr;
-    close();
+      close();
+    }
   }
 }