Re: [HACKERS] _text problem in union - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] _text problem in union
Date
Msg-id 199909280138.VAA23160@candle.pha.pa.us
Whole thread Raw
In response to Re: [HACKERS] _text problem in union  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
> Zakkr <zakkr@zf.jcu.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

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