Re: Implement <null treatment> for window functions

From: Vik Fearing <vik(at)postgresfriends(dot)org>
To: Zhihong Yu <zyu(at)yugabyte(dot)com>, Krasiyan Andreev <krasiyan(at)gmail(dot)com>
Cc: David Fetter <david(at)fetter(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Implement <null treatment> for window functions
Date: 2021-01-08 00:02:52
Message-ID: 239b0840-9ade-a4cf-86a0-7fb3e58a564b@postgresfriends.org
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On 1/1/21 10:21 PM, Zhihong Yu wrote:
> Krasiyan:
> Happy New Year.
>
> For WinGetFuncArgInPartition():
>
> + if (target > 0)
> + step = 1;
> + else if (target < 0)
> + step = -1;
> + else
> + step = 0;
>
> When would the last else statement execute ? Since the above code is
> for WINDOW_SEEK_CURRENT, I wonder why step should be 0.

Hi.

"lag(expr, 0) over w" is useless but valid.
--
Vik Fearing

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