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https://issues.apache.org/jira/browse/SOLR-1709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12994853#comment-12994853
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Bill Bell commented on SOLR-1709:
---------------------------------

1 vote for 3.1

> Distributed Date Faceting
> -------------------------
>
>                 Key: SOLR-1709
>                 URL: https://issues.apache.org/jira/browse/SOLR-1709
>             Project: Solr
>          Issue Type: Improvement
>          Components: SearchComponents - other
>    Affects Versions: 1.4
>            Reporter: Peter Sturge
>            Priority: Minor
>         Attachments: FacetComponent.java, FacetComponent.java, 
> ResponseBuilder.java, SOLR-1709_distributed_date_faceting_v3x.patch, 
> solr-1.4.0-solr-1709.patch
>
>
> This patch is for adding support for date facets when using distributed 
> searches.
> Date faceting across multiple machines exposes some time-based issues that 
> anyone interested in this behaviour should be aware of:
> Any time and/or time-zone differences are not accounted for in the patch 
> (i.e. merged date facets are at a time-of-day, not necessarily at a universal 
> 'instant-in-time', unless all shards are time-synced to the exact same time).
> The implementation uses the first encountered shard's facet_dates as the 
> basis for subsequent shards' data to be merged in.
> This means that if subsequent shards' facet_dates are skewed in relation to 
> the first by >1 'gap', these 'earlier' or 'later' facets will not be merged 
> in.
> There are several reasons for this:
>   * Performance: It's faster to check facet_date lists against a single map's 
> data, rather than against each other, particularly if there are many shards
>   * If 'earlier' and/or 'later' facet_dates are added in, this will make the 
> time range larger than that which was requested
>         (e.g. a request for one hour's worth of facets could bring back 2, 3 
> or more hours of data)
>     This could be dealt with if timezone and skew information was added, and 
> the dates were normalized.
> One possibility for adding such support is to [optionally] add 'timezone' and 
> 'now' parameters to the 'facet_dates' map. This would tell requesters what 
> time and TZ the remote server thinks it is, and so multiple shards' time data 
> can be normalized.
> The patch affects 2 files in the Solr core:
>   org.apache.solr.handler.component.FacetComponent.java
>   org.apache.solr.handler.component.ResponseBuilder.java
> The main changes are in FacetComponent - ResponseBuilder is just to hold the 
> completed SimpleOrderedMap until the finishStage.
> One possible enhancement is to perhaps make this an optional parameter, but 
> really, if facet.date parameters are specified, it is assumed they are 
> desired.
> Comments & suggestions welcome.
> As a favour to ask, if anyone could take my 2 source files and create a PATCH 
> file from it, it would be greatly appreciated, as I'm having a bit of trouble 
> with svn (don't shoot me, but my environment is a Redmond-based os company).

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