private function initActionsTables()
    {
        $this->actionsTablesByType = array();
        foreach (Metrics::$actionTypes as $type) {
            $dataTable = new DataTable();
            if ($type === Action::TYPE_SITE_SEARCH) {
                $maxRows = ArchivingHelper::$maximumRowsInDataTableSiteSearch;
            } else {
                $maxRows = ArchivingHelper::$maximumRowsInDataTableLevelZero;
            }
            $dataTable->setMaximumAllowedRows($maxRows);

            if ($type == Action::TYPE_PAGE_URL
                || $type == Action::TYPE_PAGE_TITLE
            ) {
                // for page urls and page titles, performance metrics exist and have to be aggregated correctly
                $dataTable->setMetadata(DataTable::COLUMN_AGGREGATION_OPS_METADATA_NAME, Metrics::$columnsAggregationOperation);
            }

            $this->actionsTablesByType[$type] = $dataTable;
        }
    }