[cboumalh]

Switches the per-entry deserialization buffer from an allocated nb::bytes (which copied the full remaining serialized blob on every retained entry, producing O(N²) copy work on large sketches) to a zero-copy memoryview over the C++ buffer. Updates the PyObjectSerDe.from_bytes contract from bytes to a buffer-protocol object and adjusts PyStringsSerDe accordingly. Also fixing a 3-byte length-prefix read that corrupted string summaries.

default performance:

Building compact tuple sketch: lg_k=19 (k=524288), n=524288
  build time: 0.27 s, estimate=524288, retained=524288
           serialize: mean=  176.46 ms  stdev=   0.00 ms  min=  176.46 ms  n=1
  serialized size: 6,291,472 bytes
         deserialize: mean=73239.24 ms  stdev=   0.00 ms  min=73239.24 ms  n=1

performance with memory view:

Building compact tuple sketch: lg_k=19 (k=524288), n=524288
  build time: 0.21 s, estimate=524288, retained=524288
           serialize: mean=  147.77 ms  stdev=   0.00 ms  min=  147.77 ms  n=1
  serialized size: 6,291,472 bytes
         deserialize: mean=  150.76 ms  stdev=   0.00 ms  min=  150.76 ms  n=1

bench_tuple_serde.py

[cboumalh]

Hi @leerho @tisonkun @proost, hope all is well. Please let me know if this is worth pursuing!