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https://issues.apache.org/jira/browse/TEZ-678?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13887059#comment-13887059
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Siddharth Seth commented on TEZ-678:
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Finally got through the entire patch.
On the API
- AliasEdge ctor could do with some Javadocs ; toString fix
- AliasVertex - I think VertexGroup is a better name for this. Do we need to
maintain order of vertices internally (depending on addVertexGroup)
- DAG.createAlias seems a little out of place, why should the DAG provide a
static Alias creator. Could just let users instantiate AliasVertex / VertexGroup
- DAG.addVertexGroup(..) would be a useful API to have (and avoid adding
vertices individually)
- Vertex - some of the changes don't seem like they're required / used.
removeVertex, addAliasInputs, getAliasInputs
- MergedLogicalInput - Having initialize() and close() Javadoc specifiy the
contract would be useful. Who's supposed to close inputs, etc
On the AM
- The transition change - moving to TERMINATING - the DAG may end up staying in
this state and not moving to FAILED/KILLED.
- commitOutput returns false if it succeeds, and true if it fails ; same with
vertexSucceeded. Seems the opposite of what it should be.
- VertexState.COMMIT_FAILURE needs to be handled in VertexImpl - this will
likely put the DAG into an ERROR state.
Runtime
- AliasOutputSpec isn't required
> Support for union operations
> ----------------------------
>
> Key: TEZ-678
> URL: https://issues.apache.org/jira/browse/TEZ-678
> Project: Apache Tez
> Issue Type: Improvement
> Reporter: Bikas Saha
> Assignee: Bikas Saha
> Attachments: TEZ-678.1.patch, TEZ-678.2.patch, TEZ-678.3.patch,
> TEZ-678.4.patch, TEZ-678.5.patch, TEZ-678.6.patch, TEZ-678.7.patch
>
>
> Unions represent a collection of results obtained from different branches of
> computation. The collection is a virtual operation that does not need to
> execute any tasks. Subsequent operations can conveniently work on the union
> named data set instead of each individual member of the union. While unions
> can be implemented efficiently without additional support from Tez, having
> API support can make it easier and less error-prone to implement.
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