[jira] [Commented] (LUCENE-5914) More options for stored fields compression

["Robert Muir (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-5914?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14116926#comment-14116926 ] 

Robert Muir commented on LUCENE-5914:
-------------------------------------

[~jpountz] well I just was curious about the motivation behind it. 

There are advantages and disadvantages to each way, but as separate formats each use case would really be able to proceed in its own direction in the future. 

With the current patch, BEST_COMPRESSION = Deflate, but what if we wanted to replace this with bzip later and still support the old indexes etc (which I think is a goal of this issue). 

So I think its better to have separate formats (if they want to share some code behind the scenes at the moment, thats ok). If we want to provide back compat on both options, then thats something we can decide to do here (IMO, there should be a "price" for the added complexity, such as moving all ancient codecs out of lucene/core, dropping 3.x index support, something to keep it all manageable).


> More options for stored fields compression
> ------------------------------------------
>
>                 Key: LUCENE-5914
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5914
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Adrien Grand
>            Assignee: Adrien Grand
>             Fix For: 4.11
>
>         Attachments: LUCENE-5914.patch
>
>
> Since we added codec-level compression in Lucene 4.1 I think I got about the same amount of users complaining that compression was too aggressive and that compression was too light.
> I think it is due to the fact that we have users that are doing very different things with Lucene. For example if you have a small index that fits in the filesystem cache (or is close to), then you might never pay for actual disk seeks and in such a case the fact that the current stored fields format needs to over-decompress data can sensibly slow search down on cheap queries.
> On the other hand, it is more and more common to use Lucene for things like log analytics, and in that case you have huge amounts of data for which you don't care much about stored fields performance. However it is very frustrating to notice that the data that you store takes several times less space when you gzip it compared to your index although Lucene claims to compress stored fields.
> For that reason, I think it would be nice to have some kind of options that would allow to trade speed for compression in the default codec.



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