[jira] [Commented] (JENA-1757) Deprecate GraphStatisticsHandler

["Andy Seaborne (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-1757?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16928438#comment-16928438 ] 

Andy Seaborne commented on JENA-1757:
-------------------------------------

The [PR#604|https://github.com/apache/jena/pull/604] an illustration at the moment and it woudkl need the tests cleaning up to be suitable for merging.

> Deprecate GraphStatisticsHandler
> --------------------------------
>
>                 Key: JENA-1757
>                 URL: https://issues.apache.org/jira/browse/JENA-1757
>             Project: Apache Jena
>          Issue Type: Task
>          Components: Core
>    Affects Versions: Jena 3.12.0
>            Reporter: Andy Seaborne
>            Assignee: Andy Seaborne
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Graph statistics give the number of for "S P O" where S, P or O can be a wildcard.
> This didn't quite work out for query optimization - the needs for optimization are a little more complicated, needing information such as "if S is going to fixed, estimate the number of "S P O" with out yet knowing what S is fixed as, or it might be one of several values.
> The only significant implementation is \{{GraphMemStatisticsHandler}} for the plain memory graphs. It does exploit the mem indexes to get the count, compared to counting a "find" but the improvement appears to be small. 
> Proposal: deprecate {{GraphStatisticsHandler}}, retain the mem code "just in case".
> This will clear the way for either removal or incompatible change in the future.
>  



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