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https://issues.apache.org/jira/browse/LENS-274?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14326703#comment-14326703
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Amareshwari Sriramadasu commented on LENS-274:
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While running examples noticed that server is spending 600- 700ms in rewriting:
{noformat}
Query:cube select id,name from sample_dim where name != 'first'
Status:SUCCESSFUL:Query is successful! - Result Available
Total time in millis:670
Driver run time in millis:4
Result:
2 second
3 third
--------------------
Query:cube select id,name from sample_dim order by name
Status:SUCCESSFUL:Query is successful! - Result Available
Total time in millis:744
Driver run time in millis:1
Result:
1 first
2 second
3 third
--------------------
Query:cube select id,name from sample_dim order by name desc
Status:SUCCESSFUL:Query is successful! - Result Available
Total time in millis:732
Driver run time in millis:1
Result:
3 third
2 second
1 first
--------------------
{noformat}
Planning to profile all the resolvers and see how this can be improved.
> 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
> 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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