The order in which segments get searched depends on the order of a List
that IndexWriter internally maintains (IndexWriter.segmentInfos.segments).
When segments get flushed, they are appended to the end of this list of
segments. So more recent segments get
However when segments get merged together, the new (merged) segment takes
the smallest index of the merged segments, so even though this merged
segment is the most recent one, it could be at any index within
SegmentInfos (which defines the order in which segments get searched today).
A benefit of this approach is that if you have an append-only workload and
a merge policy that only merges adjacent segments like LogDocMergePolicy
and LogByteMergePolicy, then your global doc IDs are stable over time.
However beware that this is not true with TieredMergePolicy, which may
occasionally merge non-adjacent segments.
On Fri, Apr 16, 2021 at 7:22 AM nic k <ksk1004zz@gmail.com> wrote:
> hello i have a question, so im sending u an e-mail
>
> when searching in lucene, i wonder if it reads from the oldest segment or
> the most recently created segment
>
> when i test it, i think it reads the oldest file first, but i ask for
> conviction, not conjecture
> please im looking around and i cant figure it out so i ask
> thank u
>
--
Adrien