[jira] Commented: (LUCENE-1727) Order of stored Fields not maintained

["Yonik Seeley (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-1727?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12726098#action_12726098 ] 

Yonik Seeley commented on LUCENE-1727:
--------------------------------------

If we start guaranteeing that fields get returned in the same order as they were added, what are the costs?  (I'm not sure there ever was such a guarantee... just because someone added it to the FAQ doesn't make it so).

AFAIK, sorting the fields is necessary to group multiple values for the same field, and it also ensured that segments with the same fields had the same field numbers, which enables faster segment merging?

> Order of stored Fields not maintained
> -------------------------------------
>
>                 Key: LUCENE-1727
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1727
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Index
>    Affects Versions: 2.4, 2.4.1
>            Reporter: Hoss Man
>            Assignee: Michael McCandless
>             Fix For: 2.9
>
>
> As noted in these threads...
> http://www.nabble.com/Order-of-fields-returned-by-Document.getFields%28%29-to21034652.html
> http://www.nabble.com/Order-of-fields-within-a-Document-in-Lucene-2.4%2B-to24210597.html
> somewhere prior to Lucene 2.4.1 a change was introduced that prevents the Stored fields of a Document from being returned in same order that they were originally added in.  This can cause serious performance problems for people attempting to use LoadFirstFieldSelector or a custom FieldSelector with the LOAD_AND_BREAK, or the SIZE_AND_BREAK options (since the fields don't come back in the order they expect)
> Speculation in the email threads is that the origin of this bug is code introduced by LUCENE-1301 -- but the purpose of that issue was refactoring, so if it really is the cause of the change this would seem to be a bug, and not a side affect of a conscious implementation change.
> Someone who understands indexing internals should investigate this.  At a minimum, if it's decided that this is not actual a bug, then prior to resolving this bug the wiki docs and some of the FIeldSelector javadocs should be updated to make it clear what order Fields will be returned in.

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