diff -r c69670b7b4ef -r 98be80d2e65b src/GrepHandler.h
--- a/src/GrepHandler.h	Tue May 11 18:30:50 2021 +0200
+++ b/src/GrepHandler.h	Tue May 11 20:42:22 2021 +0200
@@ -73,7 +73,7 @@
 		currentSearchableAttributes.resize(attributes.size(), false);
 		currentFilter = nullptr;
 		for (int i = 0; i < configuration.relationConfigurations.size(); i++) {
-			if (regex_match(name, configuration.relationConfigurations[i].relationPattern)) {
+			if (regex_match(name, configuration.relationConfigurations[i].relationPattern) ^ configuration.relationConfigurations[i].invertMatch[RelationConfiguration::ENTITY::RELATION]) {
 				currentFilter = &configuration.relationConfigurations[i];
 				break;
 			}
@@ -81,7 +81,7 @@
 
 		if (currentFilter) {
 			for (int i = 0; i < currentSearchableAttributes.size(); i++) {
-				currentSearchableAttributes[i] = regex_match(attributes[i].getAttributeName(), currentFilter->attributePattern);
+				currentSearchableAttributes[i] = regex_match(attributes[i].getAttributeName(), currentFilter->attributePattern) ^ currentFilter->invertMatch[RelationConfiguration::ENTITY::ATTRIBUTE];
 			}
 		}
 
@@ -94,11 +94,13 @@
 
 			if (currentSearchableAttributes[currentAttributeIndex]) {
 				includeCurrentRecord |= regex_search(value, currentFilter->valuePattern);
+				// includeCurrentRecord ^= currentFilter->invertMatch[RelationConfiguration::ENTITY::VALUE]; // might be inverted here, but it would be probably less useful
 			}
 
 			currentAttributeIndex++;
 
 			if (currentAttributeIndex > 0 && currentAttributeIndex % currentSearchableAttributes.size() == 0) {
+				includeCurrentRecord ^= currentFilter->invertMatch[RelationConfiguration::ENTITY::VALUE];
 				if (includeCurrentRecord) for (string_t v : currentRecord) relationalWriter->writeAttribute(v);
 				includeCurrentRecord = false;
 			}