Thank you for your contribution. The zvec maintainer team is currently on holiday for the Chinese New Year (Spring Festival) in mainland China. Please expect delayed responses, and we appreciate your patience.

Added a quantized-path regression test for segment compaction:\n\n- New CompactTask_QuantizedVectorIndexThreeSegmentsRegression in segment_helper_test.cc.\n- Covers multi-segment, no-filter compaction with quantized vector indexes and verifies quantized index availability after compaction.\n\nThis is intended to directly exercise the get_quant_vector_indexer(...) merge-reuse path.

Added the quantized-path regression test for segment compaction, and the PR is otherwise unchanged. This should be ready for maintainer review when bandwidth allows.

Thanks a lot for the contribution, and sorry for the long delay on this review — we had some internal bandwidth constraints. We've made PR/issue handling to a regular cadence :)

On the change itself: I feel this optimization is better placed in the core reducer layer(mixed_streamer_reducer) rather than the DB layer. If it stays only in DB, users of core directly can’t benefit from it. What do you think?

Also, nice improvement on deduplicating repeated merge logic. One more cleanup suggestion: merge_options construction could likely be moved out of the lambda and built once outside the loop.