public inbox for [email protected]  

help / color / mirror / Atom feed

From: Vik Fearing <[email protected]>
To: Ankit Kumar Pandey <[email protected]>
To: David Rowley <[email protected]>
Cc: pghackers <[email protected]>
Subject: Re: Todo: Teach planner to evaluate multiple windows in the optimal order
Date: Sun, 8 Jan 2023 17:06:13 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<CAApHDvp=r1LnEKCmWCYaruMPL-jP4j_sdc8yeFYwaDT1ac5GsQ@mail.gmail.com>
	<[email protected]>
	<CAApHDvq=g2=ny59f1bvwRVvupsgPHK-KjLPBsSL25fVuGZ4idQ@mail.gmail.com>
	<[email protected]>
	<[email protected]>
	<[email protected]>
	<CAApHDvruS-3gG_KYXPb_=Um_TfUXi+G4o7VyBVbChTjThXF2yA@mail.gmail.com>
	<[email protected]>
	<[email protected]>
	<CAApHDvpEYcQ7d-c6Lje26gLi4dXOM3qQ9nrTe1Z241tT8nBiCg@mail.gmail.com>
	<[email protected]>
	<CAApHDvp8BpUEo_kQdGHWNPCjcmRWCdiy5p26SoQA4R6rinkaLA@mail.gmail.com>
	<[email protected]>
	<[email protected]>

On 1/8/23 11:21, Ankit Kumar Pandey wrote:
> 
> Please find attached patch with addressed issues mentioned before.


I am curious about this plan:

+-- ORDER BY's in multiple Window functions can be combined into one
+-- if they are subset of QUERY's ORDER BY
+EXPLAIN (COSTS OFF)
+SELECT empno,
+       depname,
+       min(salary) OVER (PARTITION BY depname ORDER BY empno) depminsalary,
+       sum(salary) OVER (PARTITION BY depname) depsalary,
+       count(*) OVER (ORDER BY enroll_date DESC) c
+FROM empsalary
+ORDER BY depname, empno, enroll_date;
+                      QUERY PLAN
+------------------------------------------------------
+ WindowAgg
+   ->  WindowAgg
+         ->  Sort
+               Sort Key: depname, empno, enroll_date
+               ->  WindowAgg
+                     ->  Sort
+                           Sort Key: enroll_date DESC
+                           ->  Seq Scan on empsalary
+(8 rows)
+


Why aren't min() and sum() calculated on the same WindowAgg run?
-- 
Vik Fearing

view thread (60+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected]
  Subject: Re: Todo: Teach planner to evaluate multiple windows in the optimal order
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox