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https://issues.apache.org/jira/browse/LENS-274?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Arshad Matin closed LENS-274.
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> Add estimate api in driver and REST api in server
> -------------------------------------------------
>
> Key: LENS-274
> URL: https://issues.apache.org/jira/browse/LENS-274
> Project: Apache Lens
> Issue Type: Improvement
> Components: api
> Reporter: Amareshwari Sriramadasu
> Assignee: Amareshwari Sriramadasu
> Labels: incompatible
> Fix For: 2.1
>
>
> Add estimate api in LensDriver with following :
> * Estimates the query cost
> * Should return with very less latency - in 10 of milli seconds.
> /**
> * Estimates the query cost.
> * This should be returned with very less latency - should return in 10 of
> milli seconds.
> * @param ctx The query context
> *
> * @return The query cost object indicating estimated run time and resource
> usage.
> * @throws LensException the lens exception if cannot estimate
> */
> QueryCost estimate(AbstractQueryContext ctx) throws LensException;
> h3. Why do we need such api besides explain?
> Explain is more elaborative which gives plan of the query with respect to
> execution as well. When we are using explain for comparison across drivers,
> we would need only the cost and the full plan is not required. So, this api
> will be used to know the query cost and pick an appropriate driver quickly.
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