  We provide an evaluation of an analytical workload in a confidential
computing environment, combining DuckDB with two technologies: modular columnar
encryption in Parquet files (data at rest) and the newest version of the Intel
SGX Trusted Execution Environment (TEE), providing a hardware enclave where
data in flight can be (more) securely decrypted and processed. One finding is
that the "performance tax" for such confidential analytical processing is
acceptable compared to not using these technologies. We eventually manage to
run TPC-H SF30 with under 2x overhead compared to non-encrypted, non-enclave
execution; we show that, specifically, columnar compression and encryption are
a good combination. Our second finding consists of dos and don'ts to tune
DuckDB to work effectively in this environment. There are various performance
hazards: potentially 5x higher cache miss costs due to memory encryption inside
the enclave, NUMA penalties, and highly elevated cost of swapping pages in and
out of the enclave -- which is also triggered indirectly by using a
non-SGX-aware malloc library.
