Thread: BUG #1171: select distinct 'value',... fails.

The following bug has been logged online:

Bug reference:      1171
Logged by:          Harro Lock

Email address:      harro1@dataleaf.nl

PostgreSQL version: 7.4

Operating system:   Linux

Description:        select distinct 'value',... fails.

Details:

'select distinct' fails when using a string value in the columnlist.

Here is a minimal query that reproduces the bug:

    select distinct 'value';

This should give "value" as a result, but it produces this error-message:

ERROR:  Unable to identify an ordering operator '<' for type '"unknown"'
        Use an explicit ordering operator or modify the query


A work-around for this bug is to cast the string to a known type:

    select distinct cast('value' as varchar);

"PostgreSQL Bugs List" <pgsql-bugs@postgresql.org> writes:
>     select distinct 'value';
> ERROR:  Unable to identify an ordering operator '<' for type '"unknown"'
>         Use an explicit ordering operator or modify the query

This is accepted in 7.4 and later.  You are evidently using something
older.

            regards, tom lane