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

From Bruce Momjian
Subject Re: [HACKERS] _text problem in union
Date
Msg-id 199909271542.LAA16213@candle.pha.pa.us
Whole thread Raw
In response to _text problem in union  (Zakkr <zakkr@zf.jcu.cz>)
List pgsql-hackers
> 
>  Hi,
> 
>  I have small problem with text array in union query..     see:
> 
> 
> abil=> select 5 union select 5;
> ?column?
> --------
>        5
> (1 row)
> 
> abil=> select 5 union select 6;
> ?column?
> --------
>        5
>        6
> (2 rows)
> 
> abil=> select '{"aaa"}'::_text union select '{"aaa"}'::_text;
> ?column?
> --------
> {"aaa"} 
> (1 row)
> 
> 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
> abil=> 

Good problem description.  Seems we can't compare arrays of text fields.

Seems if we have an array of text fields, we could compare each element
one-by-one using the base type until we get a comparison result.

Not sure if this should make the TODO list or not.

--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
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