[
https://issues.apache.org/jira/browse/LUCENE-9447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17172510#comment-17172510
]
Robert Muir commented on LUCENE-9447:
-------------------------------------
>From my experiments done on LUCENE-6100, increasing block size for the most
>part is a workaround, it only helps hide the waste of rebooting the deflate
>dictionary from *scratch* for every block? So the "crappy preset" tried to
>show that there.
Sadly I couldn't find a decent/simple way to use preset dictionary that made me
happy with what is available in the JDK. It doesn't expose some zlib methods
that you would need (e.g. retrieving current dictionary) and as I mentioned,
there were some inefficiencies, at least with how we had compression hooked in
at the time.
> Make BEST_COMPRESSION compress more aggressively?
> -------------------------------------------------
>
> Key: LUCENE-9447
> URL: https://issues.apache.org/jira/browse/LUCENE-9447
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Adrien Grand
> Priority: Minor
>
> The Lucene86 codec supports setting a "Mode" for stored fields compression,
> that is either "BEST_SPEED", which translates to blocks of 16kB or 128
> documents (whichever is hit first) compressed with LZ4, or
> "BEST_COMPRESSION", which translates to blocks of 60kB or 512 documents
> compressed with DEFLATE with default compression level (6).
> After looking at indices that spent most disk space on stored fields
> recently, I noticed that there was quite some room for improvement by
> increasing the block size even further:
> ||Block size||Stored fields size||
> |60kB|168412338|
> |128kB|130813639|
> |256kB|113587009|
> |512kB|104776378|
> |1MB|100367095|
> |2MB|98152464|
> |4MB|97034425|
> |8MB|96478746|
> For this specific dataset, I had 1M documents that each had about 2kB of
> stored fields each and quite some redundancy.
> This makes me want to look into bumping this block size to maybe 256kB. It
> would be interesting to re-do the experiments we did on LUCENE-6100 to see
> how this affects the merging speed. That said I don't think it would be
> terrible if the merging time increased a bit given that we already offer the
> BEST_SPEED option for CPU-savvy users.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org
For additional commands, e-mail: issues-h...@lucene.apache.org
