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https://issues.apache.org/jira/browse/KYLIN-2286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15760221#comment-15760221
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liyang commented on KYLIN-2286:
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The requirement is worth discussion. Whether or not today's lookup should
affect history result is case by case. Yu's case wants latest result, while
I've seen many cases that history result is preferred.
This issue has been discussed years ago, when Kylin is in very early stage. And
we have decided that Kylin should return data exactly as the time a
cube/segment is built. The idea is simple. Once built, the data is immutable.
That said, I understand Yu's requirement represents a good many of other users.
We can brainstorm how to satisfy those cases here.
> global snapshot table for one cube
> -----------------------------------
>
> Key: KYLIN-2286
> URL: https://issues.apache.org/jira/browse/KYLIN-2286
> Project: Kylin
> Issue Type: Improvement
> Reporter: fengYu
> Assignee: fengYu
>
> I current version, Kylin build a snapshot table for a segment and isolate
> with each other in the same cube, even though some segments share the same
> snapshot table storage .
> I some scene， we need global snapshot table for one cube, such as we has a
> cube with snapshot table,ID is PK，the first day, the table look like:
> id name
> 1 A
> 2 B
> 3 C
> the query 'select name, count(1) from fact join dimension group by name' get
> result:
> A xx
> B xx
> C xx
> the next day(segment), lookup table modified, it looks like :
> id name
> 1 A
> 2 D
> 3 E
> the same query return :
> A xx
> B xx
> C xx
> D xx
> E xx
> However B and D, C and E has the same ID, we need the newest result. so a
> global snapshot table shared by all segments which has always the newest
> values is needed.
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