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https://issues.apache.org/jira/browse/ATLAS-1379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15795582#comment-15795582
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David Kantor commented on ATLAS-1379:
-------------------------------------
This change has been available for review since Dec 16. It will be committed
tomorrow (Wed Jan 4 2016) unless there are further comments on review board.
> Avoid object query overhead when report query selects class type alias
> ----------------------------------------------------------------------
>
> Key: ATLAS-1379
> URL: https://issues.apache.org/jira/browse/ATLAS-1379
> Project: Atlas
> Issue Type: Improvement
> Reporter: Neeru Gupta
> Assignee: Neeru Gupta
> Labels: performance
> Fix For: 0.8-incubating
>
> Attachments: rb54759.patch
>
>
> When the DSL query is selecting the class alias, which causes Atlas to run an
> object query. Atlas should detect this query construct and avoid the overhead
> of full entity retrieval, when the entity ends up being serialized as an
> structure that just contains the guid, type, and status.
> For queries like: 'from hive_db as h select h', even though the end result
> only contains id object, Atlas code initially loads the entire object with
> all its properties and while serializing it ends up serializing only the id
> part. This bug is to avoid the overhead of loading the entire object when
> fields other than id will be discarded anyways. This added a lot of overhead
> and was identified as hotspot in our internal testing. This is specially
> relevant when large number of objects are retrieved as search results.
> Note that the fixes are backward compatible. The end result remains the same.
> Only the overwork to load unnecessary fields is avoided.
> Sample Query: 'from hive_db as h select h'
> Result:
> rows":[
> {
> "$typeName$":"__tempQueryResultStruct2",
> "id":{
> "id":"8159ee38-ec29-4d9a-845a-86fe17ab6bdb",
> "$typeName$":"hive_db",
> "version":0,
> "state":"ACTIVE"
> }
> },
> {
> "$typeName$":"__tempQueryResultStruct2",
> "id":{
> "id":"33016845-4b71-4d56-b131-b48ea38e5507",
> "$typeName$":"hive_db",
> "version":0,
> "state":"ACTIVE"
> }
> },
> {
> "$typeName$":"__tempQueryResultStruct2",
> "id":{
> "id":"b6fb9c53-680e-4be7-b143-f8d9355c5726",
> "$typeName$":"hive_db",
> "version":0,
> "state":"ACTIVE"
> }
> }
> ]
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