pub const BINARY_FALLBACK_KEY_LIMIT: usize = 4;Expand description
The maximum number of distinct join-key variables supported by
the existing binary-fallback executor. Borrowed verbatim from the
pack_keys_gpu_on_stream constraint in
xlog-cuda/src/provider/relational.rs.
This is a binary-fallback constraint, not a hypergraph
property. WCOJ eligibility uses ExecutorContext::WcojEligible
and a separate context limit; hash fallback continues to use
this value verbatim.