Hi,
You can change calcite default encoding via custom java option in dremio-env configuration file.
Here is example how set encoding to UTF-16:
DREMIO_JAVA_SERVER_EXTRA_OPTS=’-Dsaffron.default.charset=UTF-16LE -Dsaffron.default.nationalcharset=UTF-16LE -Dsaffron.default.collation.name=UTF-16LE$en_US’