Re: Why is fncollation in FunctionCallInfoData rather than fmgr_info?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Why is fncollation in FunctionCallInfoData rather than fmgr_info?
Date: 2018-06-06 05:01:49
Message-ID: 9136.1528261309@sss.pgh.pa.us
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Andres Freund <andres(at)anarazel(dot)de> writes:
> In my understanding FunctionCallInfoData is basically per-call data,
> whereas FmgrInfo is information about the function. It makes some sense
> that ->context is in FunctionCallInfoData, after all it's used for
> per-row data like the trigger context. But we don't really change the
> collation of function invocations per-call. Thus I don't quite get why
> FunctionCallInfoData contains information about it rather than FmgrInfo.

[squint] I would say that the call collation is an argument, not a
property of the function, and therefore is correctly located in
FunctionCallInfoData.

It's true that we often abuse fn_extra to hold data that's essentially
call-site-dependent, but I don't think that's a good reason to push
collation into FmgrInfo.

regards, tom lane

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