Date: Mon, 21 May 2018 08:48:13 -0700 (MST)
From: mlunnon <mlunnon@rwa-net.co.uk>
To: pgsql-performance@postgresql.org
Message-ID: <1526917693149-0.post@n3.nabble.com>
In-Reply-To: <1526883356469-0.post@n3.nabble.com>
References: <1526883356469-0.post@n3.nabble.com>
Subject: Re: Help me in reducing the CPU cost for the high cost query below,
 as it is hitting production seriously!!
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Precedence: bulk

pavan95 wrote
> *Query*:
> 
> explain select ... from tms_timesheet_details, tms_wsr_header header  
> where wsr_header_id=header.id and work_order_no != 'CORPORATE';
> 
>                                          QUERY PLAN
> ---------------------------------------------------------------------------------------------
>  Aggregate  (cost=9868.91..9868.92 rows=1 width=8)
>    ->  Hash Join  (cost=608.27..5647.67 rows=70354 width=8)
>          Hash Cond: (tms_timesheet_details.wsr_header_id = header.id)
>          ->  Seq Scan on tms_timesheet_details  (cost=0.00..3431.14
> rows=72378 width=12)
>                Filter: ((work_order_no)::text <> 'CORPORATE'::text)
>          ->  Hash  (cost=399.23..399.23 rows=16723 width=4)
>                ->  Seq Scan on tms_wsr_header header  (cost=0.00..399.23
> rows=16723 width=4)
> (7 rows)
> 
> 
> --
> Sent from:
> http://www.postgresql-archive.org/PostgreSQL-performance-f2050081.html

Why is the table tms_wsr_header in the from clause as it is not used in the
select columns? A simple "wsr_header_id is not null" would do the same as
this is a foreign key into the tms_wsr_header table. An index with on
tms_timesheet_details.id "where wsr_header_id is not null" might then speed
the query up if there were significant numbers of rows with a null
wsr_header_id.
Cheers
Matthew


--
Sent from: http://www.postgresql-archive.org/PostgreSQL-performance-f2050081.html