How can I get the total run time of a query in redshift, with a query?

问题

I'm in the process of benchmarking some queries in redshift so that I can say something intelligent about changes I've made to a table, such as adding encodings and running a vacuum. I can query the stl_query table with a LIKE clause to find the queries I'm interested in, so I have the query id, but tables/views like stv_query_summary are much too granular and I'm not sure how to generate the summarization I need!

The gui dashboard shows the metrics I'm interested in, but the format is difficult to store for later analysis/comparison (in other words, I want to avoid taking screenshots). Is there a good way to rebuild that view with sql selects?

回答1:

To add to Alex answer, I want to comment that stl_query table has the inconvenience that if the query was in a queue before the runtime then the queue time will be included in the run time and therefore the runtime won't be a very good indicator of performance for the query.

To understand the actual runtime of the query, check on stl_wlm_query for the total_exec_time.

select total_exec_time
from stl_wlm_query
where query='query_id'

回答2:

There are some usefuls tools/scripts in https://github.com/awslabs/amazon-redshift-utils

Here is one of said scripts stripped out to give you query run times in milliseconds. Play with the filters, ordering etc to show the results you are looking for:

select userid, label, stl_query.query, trim(database) as database, trim(querytxt) as qrytext, starttime, endtime, datediff(milliseconds, starttime,endtime)::numeric(12,2) as run_milliseconds, 
       aborted, decode(alrt.event,'Very selective query filter','Filter','Scanned a large number of deleted rows','Deleted','Nested Loop Join in the query plan','Nested Loop','Distributed a large number of rows across the network','Distributed','Broadcasted a large number of rows across the network','Broadcast','Missing query planner statistics','Stats',alrt.event) as event
from stl_query 
left outer join ( select query, trim(split_part(event,':',1)) as event from STL_ALERT_EVENT_LOG group by query, trim(split_part(event,':',1)) ) as alrt on alrt.query = stl_query.query
where userid <> 1 
-- and (querytxt like 'SELECT%' or querytxt like 'select%' ) 
-- and database = ''
order by starttime desc
limit 100

来源：https://stackoverflow.com/questions/41473901/how-can-i-get-the-total-run-time-of-a-query-in-redshift-with-a-query