Re: [HACKERS] _text problem in union

From: Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Zakkr <zakkr(at)zf(dot)jcu(dot)cz>, pgsql-hackers <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Re: [HACKERS] _text problem in union
Date: 1999-09-28 01:38:28
Message-ID: 199909280138.VAA23160@candle.pha.pa.us
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> Zakkr <zakkr(at)zf(dot)jcu(dot)cz> writes:
> > abil=> select '{"aaa"}'::_text union select '{"bbb"}'::_text;
> > ERROR: Unable to identify an ordering operator '<' for type '_text'
> > Use an explicit ordering operator or modify the query
>
> Depending on what you're trying to do, UNION ALL might be an adequate
> workaround. UNION is defined to remove duplicates, so it has to sort
> the results of the union'ed queries, which requires an ordering
> operator. UNION ALL just appends the two query results together...
>
> In the long run we probably ought to think about providing ordering
> operators for array types.
>

Added to TODO:

* Allow arrays to be ORDER'ed

--
Bruce Momjian | http://www.op.net/~candle
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