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https://issues.apache.org/jira/browse/SOLR-1111?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12698399#action_12698399
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Yonik Seeley edited comment on SOLR-1111 at 4/13/09 2:50 PM:
-------------------------------------------------------------

The major issue is that Lucene now creates scorers per-segment, and if you use 
Lucene's searcher.search(...,sort) then the FieldCache populations will also be 
per-segment.

The biggest issue:  If FieldCache get's populated at both the top-level reader 
and per-segment, memory usage doubles (as does un-inversion time).
 - Faceting on single-valued fields uses the FieldCache at the top-level (and 
would be
   - This is non-trivial to change...  if we started counting per-segment, 
counts would somehow have to be merged across segments.
 - Sorting in Solr currently uses the FieldCache at the top level
   - This can't easily be changed to use Lucene's searcher.search(...,sort) 
since we are using a hit collector (which can be wrapped in a time limited 
collector).
 - Distributed search uses the top-level FieldCache to retrieve sort field 
values.
 - FunctionQuery now derives values at the segment level
   - This also applies to the function range query

Another issue for function query is the use of ord()... it won't be valid in 
multi-segment indexes if evaluated at the segment level.

      was (Author: [email protected]):
    The major issue is that Lucene now creates scorers per-segment, and if you 
use Lucene's searcher.search(...,sort) then the FieldCache populations will 
also be per-segment.

The biggest issue:  If FieldCache get's populated at both the top-level reader 
and per-segment, memory usage doubles (as does un-inversion time).
 - Faceting on single-valued fields uses the FieldCache at the top-level (and 
would be
   - This is non-trivial to change...  if we started counting per-segment, 
counts would somehow have to be merged across segments.
 - Sorting in Solr currently uses the FieldCache at the top level
   - This can't easily be changed to use Lucene's searcher.search(...,sort) 
since we are using a hit collector (which can be wrapped in a time limited 
collector).
 - Distributed search uses the top-level FieldCache to retrieve sort field 
values.
 - FunctionQuery now derives values at the segment level
   - This also applies to the function range query
  
> fix FieldCache usage in Solr
> ----------------------------
>
>                 Key: SOLR-1111
>                 URL: https://issues.apache.org/jira/browse/SOLR-1111
>             Project: Solr
>          Issue Type: Bug
>            Reporter: Yonik Seeley
>             Fix For: 1.4
>
>
> Recent changes in Lucene have altered how the FieldCache is used and as-is 
> could lead to previously working Solr installations blowing up when they 
> upgrade to 1.4.  We need to fix, or document the affects of these changes.

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