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https://issues.apache.org/jira/browse/TRAFODION-2001?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16030411#comment-16030411
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Hans Zeller commented on TRAFODION-2001:
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Good to see elasticity in Trafodion, this will be very useful! Before it can
work, we have to make some SQL compiler and maybe executor changes, though.
Until now, SQL is based on the following design:
* The nodes of a cluster have node ids 0 ... n-1
* Query plans are generated with the assumption that all n nodes are up. This
is to keep query plans stable in cases of node failures.
With the new model, we will need a new set of rules. We probably need to define
3 states of a node, up, down and missing (a "hole" in the node ids). We would
skip the missing nodes for plan generation and only consider up and down nodes.
I'll file a subtask for this JIRA so we can keep track of this work.
It's good that new nodes first fill the holes.
> Trafodion Elasticity enhancements
> ---------------------------------
>
> Key: TRAFODION-2001
> URL: https://issues.apache.org/jira/browse/TRAFODION-2001
> Project: Apache Trafodion
> Issue Type: New Feature
> Components: documentation, foundation, installer
> Affects Versions: 2.1-incubating
> Reporter: Gonzalo E Correa
> Assignee: Gonzalo E Correa
> Fix For: 2.2-incubating
>
> Attachments: TRAFODION-2001-Elasticity.docx,
> TRAFODION-2001-Elasticity.v1.5.docx,
> Trafodion-R2.2-Elasticity-TRAFODON-2001.pptx
>
> Original Estimate: 672h
> Remaining Estimate: 672h
>
> Abstract
> This JIRA proposes changes to the Apache Trafodion Incubation configuration
> and operational elements used to define and operate a Trafodion cluster in a
> Trafodion instance. The changes proposed build on existing functionality for
> enhancing Trafodion to support elasticity by implementing the ability to add
> and delete nodes used by Trafodion components.
> The concept of a cluster is defined in Trafodion through the configuration of
> nodes in the ‘sqconfig’ text file, the Trafodion configuration file. This
> configuration file is compiled to generate a set of files used to start and
> stop a Trafodion instance. The files generated consist of a configuration
> database and scripts which presently contain fixed, i.e., hardcoded,
> configuration topology attributes of a configured Trafodion instance. This
> proposal addresses this hardcoded configuration topology issue by adding new
> configuration commands in the Trafodion Foundation’s monitor components,
> changing the methodology in the scripts generated, and extending the use of
> the configuration database currently in use.
> Objectives
> The objective of this proposal is to implement elasticity capabilities in
> Trafodion to match or exceed the elasticity capabilities of other modules in
> the Hadoop eco system.
> This focuses on the Trafodion Foundation functionality. Specifically, the
> monitor components which use the configuration of nodes that define a
> Trafodion cluster are enhanced to provide at set of primitive commands to add
> and delete nodes as well as the generation of events to existing processes in
> the instance of the addition or deletion of member nodes to the cluster
> configuration.
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