Re: Query is very much slow

Am 25.05.2017 um 07:13 schrieb Daulat Ram:
>
> Hi team,
>
> We are getting very slow response of this query.
>
> SELECT date_trunc('day', insert_time),workflow.project.project_name,
>
> workflow.tool_performance.project_id,workflow.tool_performance.user_id,workflow.tool_performance.step_id,count(*),
>
> round(sum(execution_time)/1000) as
> Sum_time_sec,round(((round(sum(execution_time)/1000))/60)/count(*),2)
> as Efficency_Min,round
>
> (((round(sum(execution_time)/1000)))/count(*),2)
>
> as Efficency_sec FROM
> workflow.project,workflow.tool_performance,workflow.evidence_to_do
> WHERE workflow.project
>
> .project_id = workflow.tool_performance.project_id AND insert_time
> >'2017-05-01' AND insert_time <'2017-05-02' AND
>
> workflow.evidence_to_do.status_id in
> (15100,15150,15200,15300,15400,15500) Group BY date_trunc('day',
> insert_time),workflow.project.project_name,
>
> workflow.tool_performance.project_id,workflow.tool_performance.user_id,workflow.tool_performance.step_id
> ORDER BY
>
> workflow.tool_performance.project_id,workflow.project.project_name,
>
> workflow.tool_performance.step_id;
>
> *The following indexes are created on project & evidence_to_do table*.
>
> "CREATE INDEX project_id_idx ON workflow.project USING btree (project_id)"
>
> "CREATE INDEX evidence_to_do_status_id_index ON
> workflow.evidence_to_do USING btree (status_id)"
>
> *Explain plan of the Query is:*
>
> "GroupAggregate (cost=18675703613.60..20443753075.67 rows=6689718
> width=69)"
>
> " -> Sort (cost=18675703613.60..18823015982.33 rows=58924947492
> width=69)"
>
> " Sort Key: tool_performance.project_id, project.project_name,
> tool_performance.step_id, (date_trunc('day'::text,
> tool_performance.insert_time)), tool_performance.user_id"
>
> " -> Nested Loop (cost=2.42..884042104.67 rows=58924947492
> width=69)"
>
> " -> Seq Scan on evidence_to_do (cost=0.00..118722.17
> rows=554922 width=0)"
>
> " Filter: (status_id = ANY
> ('{15100,15150,15200,15300,15400,15500}'::bigint[]))"
>
> " -> Materialize (cost=2.42..49435.58 rows=106186 width=69)"
>
> " -> Hash Join (cost=2.42..48904.65 rows=106186
> width=69)"
>
> " Hash Cond: (tool_performance.project_id =
> project.project_id)"
>
> " -> Seq Scan on tool_performance
> (cost=0.00..47442.18 rows=106186 width=39)"
>
> " Filter: ((insert_time > '2017-05-01
> 00:00:00+05:30'::timestamp with time zone) AND (insert_time <
> '2017-05-02 00:00:00+05:30'::timestamp with time zone))"
>
> " -> Hash (cost=1.63..1.63 rows=63 width=38)"
>
> " -> Seq Scan on project
> (cost=0.00..1.63 rows=63 width=38)"
>

you will get a so-called cross join with 106186 rows from
tool_performance multiplied with 554922
rows from evidence_to_do, resulting in 58.924.947.492 rows in total. Is
that really what you want?

I think, there is a missing join-condition. It would be better to use
expliciet JOIN-Syntax to prevent such errors.

Regards, Andreas

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