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https://issues.apache.org/jira/browse/ATLAS-3043?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16759172#comment-16759172
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ASF subversion and git services commented on ATLAS-3043:
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Commit 0e0f217af2b7c142ebc1445b86ba5570a3b69684 in atlas's branch 
refs/heads/master from Madhan Neethiraj
[ https://gitbox.apache.org/repos/asf?p=atlas.git;h=0e0f217 ]

ATLAS-3043: added unique-attributes constraints at store-level

Change-Id: Ica44b1739b504bebc2ab39dc856ccb079b8f4003


> Unique attributes constraint at store-level
> -------------------------------------------
>
>                 Key: ATLAS-3043
>                 URL: https://issues.apache.org/jira/browse/ATLAS-3043
>             Project: Atlas
>          Issue Type: Bug
>          Components:  atlas-core
>            Reporter: Madhan Neethiraj
>            Assignee: Madhan Neethiraj
>            Priority: Major
>             Fix For: 2.0.0
>
>         Attachments: ATLAS-3043.patch
>
>
> Atlas data-model allows marking an attribute as unique; and on entity 
> create/update operations, Atlas verifies that this constraint is not violated 
> i.e. no more than one *active* entity of a given entity-type can have same 
> value for a unique-attribute.
> However, no store-level constraint is created to enforce uniqueness. This is 
> likely to be due to the fact that there can be multiple *deleted* entities 
> with the same typeName & unique-attribute value. And having such store-level 
> constraint wouldn't allow this to exist.
> An alternate approach is to create a 'shadow-property' at the store-level for 
> the unique-attribute; and this property should be set only for active 
> entities. When an entity is deleted, this 'shadow-property' will be removed 
> from the entity-vertex. In this approach, the unique-constraint can be set at 
> the store level for the 'shadow-property'. In addition to enforcing the 
> constraint at the store level, it might also help in quicker entity-retrieval 
> given typeName and unique-attribute.



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