feat(mem_wal): add overfetch_factor and refine_base_table to LSM vector search#6908
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jackye1995 wants to merge 1 commit into
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feat(mem_wal): add overfetch_factor and refine_base_table to LSM vector search#6908jackye1995 wants to merge 1 commit into
jackye1995 wants to merge 1 commit into
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…or search Add configurable overfetch_factor to plan_search() that makes each LSM source fetch ceil(k * factor) candidates instead of k. The larger candidate pool increases the chance that the global PK dedup sees both the fresh and stale copies of an updated PK, mitigating stale reads when the fresh version falls out of its source's top-k. Also simplify refine_factor: Option<u32> to refine_base_table: bool, since refine is always factor=1 and only applies to the base table. When overfetch is active, base-table refine is auto-enabled so approximate index distances are re-ranked to exact before the cross-source merge. Exposed in Python and Java bindings with backward-compatible overloads.
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Summary
overfetch_factortoplan_search()— each LSM source fetchesceil(k * factor)candidates instead ofk, mitigating stale reads when a PK's fresh version falls out of its source's top-k and the global dedup can't suppress the stale copy.refine_factor: Option<u32>torefine_base_table: bool— refine is always factor=1 and only applies to the base table. When overfetch is active, base-table refine is auto-enabled so approximate index distances are re-ranked to exact before the cross-source merge.