The csv_all_strings guess suggests column types within Csv files as string types. The default Csv guess suggests column types unexpected by users. To execute Data Connector correctly, users sometimes need to edit Embulk config manually and fix column types that users expect. This guess forcely suggests columns as string types.
This plugin is not included in the list of default guess plugins. And to use this plugin, users explicitly need to exclude default Csv guess from the list of default guess like:
exec: exclude_guess_plugins: ['csv'] guess_plugins: ['csv_all_strings'] in: ... type: s3 path_prefix: path/to/csvfile ...
Further details of the configuration here