pub fn set_compress_min_depth(depth: u8)Expand description
Set the youngest generational depth whose spilled bodies are compressed.
A chunk at depth d is rewritten (merged, extracted, advanced) with
frequency proportional to 2^-d under geometric merging, so compressing
a shallow chunk buys a short stay in the pool at the cost of a guaranteed
near-term codec round-trip: the body is encoded only to be read back and
decoded by the next rewrite. Generations below the floor spill under the
identity codec instead: still budgeted and swap-backed like every extent,
but encode and decode are copies. The floor never exempts a body from the
pool, so it cannot grow unbudgeted resident state.
The floor cannot strand a long-lived body uncompressed: a chunk that a
merge carries forward untouched also ages a generation, and its body is
re-spilled under the compressing codec when it crosses the floor (see
survive_merge).
0 compresses every spilled body. Consulted at every commit, so changes
apply to running dataflows.