Jonathan Hurley created AMBARI-14972:
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Summary: 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
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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