Sangjin Lee created YARN-5715:
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Summary: introduce entity prefix for return and sort order
Key: YARN-5715
URL: https://issues.apache.org/jira/browse/YARN-5715
Project: Hadoop YARN
Issue Type: Sub-task
Components: timelineserver
Reporter: Sangjin Lee
Priority: Critical
While looking into YARN-5585, we have come across the need to provide a sort
order different than the current entity id order. The current entity id order
returns entities strictly in the lexicographical order, and as such it returns
the earliest entities first. This may not be the most natural return order. A
more natural return/sort order would be from the most recent entities.
To solve this, we would like to add what we call the "entity prefix" in the row
key for the entity table. It is a number (long) that can be easily provided by
the client on write. In the row key, it would be added before the entity id
itself.
The entity prefix would be considered mandatory. On all writes (including
updates) the correct entity prefix should be set by the client so that the
correct row key is used. The entity prefix needs to be unique only within the
scope of the application and the entity type.
For queries that return a list of entities, the prefix values will be returned
along with the entity id's. Queries that specify the prefix and the id should
be returned quickly using the row key. If the query omits the prefix but
specifies the id (query by id), the query may be less efficient.
This JIRA should add the entity prefix to the entity API and add its handling
to the schema and the write path. The read path will be addressed in YARN-5585.
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