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https://issues.apache.org/jira/browse/KYLIN-2286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15753713#comment-15753713
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Shaofeng SHI edited comment on KYLIN-2286 at 12/16/16 7:34 AM:
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This sounds like the scenario of "Slowly Changing Dimensions", which isn't well
supported today: If user wants get history cube be updated (after changing
lookup table), he need go back to refresh those history segments.
Yu, is there any pre-condition for using global snapshot? I think all dimension
columns in lookuptable should be "drived", right?
was (Author: shaofengshi):
This sounds like the scenario of "Slowly Changing Dimensions", which isn't well
supported today: If user wants get history cube be updated (after changing
lookup table), he need go back to refresh those history segments.
Yu, is there any prediction for using global snapshot? I think all dimension
columns in lookuptable should be "drived", right?
> 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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