Re: add more frame types in window functions (ROWS)

From: Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
To: Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: add more frame types in window functions (ROWS)
Date: 2009-11-15 07:43:41
Message-ID: e08cc0400911142343s20dd9b2dve37d41f24f1673f@mail.gmail.com
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2009/11/15 Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>:
> My thinking is that the executor definitely shouldn't be relying on it
> being a specific node type, but should just ExecEvalExpr it on the
> first call and store the result; then you don't have to know whether
> it's a Const or Param node or a more complex expression.

Yeah, so that we allow something like ROWS BETWEEN 1 + $1 PRECEDING
AND ... And to support RANGE BETWEEN n PRECEDING ..., we should make
datum to add or to subtract from current value on initial call anyway.

Regards,

--
Hitoshi Harada

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