mattspitz wrote:
Are the index files synced on writer.close()?
No, they aren't. Not until 2.4 (trunk).
Thank you so much for your help. I think the seek time is the issue,
especially considering the high merge factor and the fact that the
segments
are scattered all over the disk.
You're welcome! I agree: optimizing seek time seems likely to be the
biggest win.
Will a faster disk cache access affect the optimization and
merging? I
don't really have a sense for what of the segments are kept in
memory during
a merge. It doesn't make sense to me that Lucene would pull all of
the
segments into memory to merge them, but I don't really know how.
Segments aren't kept in memory during merging... it's more like a
cursor that sweeps through each of the files for the 50 segments being
merged. Lucene does buffer its reads, so we read a chunk into RAM and
then pull bits off that chunk. And the OS does readahead. But
otherwise it's all on disk and we make a single sweep through each of
the segments to be merged.
So I wouldn't expect the disk cache's performance to impact Lucene,
during merging or flushing.
Mike
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