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https://issues.apache.org/jira/browse/AMBARI-14972?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Hurley updated AMBARI-14972:
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Attachment: AMBARI-14972.patch
> Add PK to servicecomponentdesiredstate Table To Support FK Relationships
> ------------------------------------------------------------------------
>
> Key: AMBARI-14972
> URL: https://issues.apache.org/jira/browse/AMBARI-14972
> Project: Ambari
> Issue Type: Task
> Components: ambari-server
> Affects Versions: 2.4.0
> Reporter: Jonathan Hurley
> Assignee: Jonathan Hurley
> Priority: Critical
> Fix For: 2.4.0
>
> Attachments: AMBARI-14972.patch
>
>
> The {{servicecomponentdesiredstate}} table currently uses a compound PK based
> off of the cluster ID, service name, and component name. There are several
> problems with this approach:
> - Primary Keys should be data that's not part of the business logic of the
> system and not subject to be changed potentially (as strings are).
> - Other tables referencing the {{servicecomponentdesiredstate}} table would
> now need knowledge of cluster/service/component in order to make the correct
> FK association. This leads to extra data being tracked as well as data
> duplication.
> - Some databases, such as SQL Server, have problems with the indexing of
> compound PKs and may lead to deadlocks when querying and updating
> concurrently.
> We should change this table so that it uses a simple PK for referencing. FK
> relationships as they exist today can still be maintained as long as a
> {{UNIQUE}} constraint is placed on the table. We should:
> - Add a {{UNIQUE}} constraint to the former PK columns
> - Add an {{INDEX}} to the former PK columns
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