Re: Missing array support

From: Joe Conway <mail(at)joeconway(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Missing array support
Date: 2003-07-01 02:15:29
Message-ID: 3F00EEC1.8080408@joeconway.com
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Tom Lane wrote:
> Joe Conway <mail(at)joeconway(dot)com> writes:
>
>>So array[] should produce '{}' of (an array) type determined by the
>>context? OK -- seems easy enough.
>
> Is it? I think we'd decided that this could only reasonably be handled
> by creating a datatype representing array-of-UNKNOWN. I'm afraid to do
> that because I think it might allow the parser's type resolution
> algorithms to follow paths we will not like. Perhaps it can be made to
> work, but I think it will require some careful study.

I took a closer look -- yeah, without array-of-UNKNOWN I don't think we
can make this work.

I got something working by forcing the element type to UNKNOWN when the
elements list is empty in transformExpr(), but then select_common_type()
turns around and turns UNKNOWN into TEXT, so you wind up with an empty
text[].

I won't bother sending that patch in because I *know* it will get
rejected ;-)

I guess we should put array-of-UNKNOWN on the list of things to look at
for 7.5.

Joe

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