From: Tom Lane <tgl@sss.pgh.pa.us>
To: Heikki Linnakangas <hlinnaka@iki.fi>
cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: eval_const_expresisions and ScalarArrayOpExpr
In-reply-to: <4b14a9a5-01c2-4042-3ec9-cf27149302a5@iki.fi>
References: <3be3b82c-e29c-b674-2163-bf47d98817b1@iki.fi>
 <23186.1494516060@sss.pgh.pa.us>
 <4b14a9a5-01c2-4042-3ec9-cf27149302a5@iki.fi>
Comments: In-reply-to Heikki Linnakangas <hlinnaka@iki.fi>
	message dated "Thu, 11 May 2017 19:20:55 +0300"
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Date: Thu, 11 May 2017 12:45:09 -0400
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Heikki Linnakangas <hlinnaka@iki.fi> writes:
> On 05/11/2017 06:21 PM, Tom Lane wrote:
>>> On a side-note, I find it a bit awkward that ScalarArrayOpExpr uses a
>>> 2-element List to hold the scalar and array arguments. Wouldn't it be
>>> much more straightforward to have explicit "Expr *scalararg" and "Expr
>>> *arrayarg" fields?

>> I think it's modeled on OpExpr, which also uses a list though you could
>> argue for separate leftarg and rightarg fields instead.

> Yeah, I think that would be better for OpExpr, too. (For an unary 
> operator, rightarg would be unused.)

I should think leftarg is the one that would go unused, for a normal
prefix unary operator.

But it seems like changing this would be way more invasive than it's
really worth.  We'd save a couple of List cells per operator, which
is certainly something, but I'm afraid you'd be touching a heck of
a lot of code.  And there are a nontrivial number of places that
share argument-processing with FuncExprs, which such a change would
break.

			regards, tom lane


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