[mantisbt-dev] Why SELECT DISTINCT in filter API

[Damien R. <dr...@ma...>]

Hi guys,

Today I looked at issue #16259 and after testing the proposed patch, I 
realized that while the fix works fine for MySQL, it breaks PostgreSQL:

ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list

See my note [1] for further details. While searching for a solution to 
the issue, I started wondering why filter_api is executing a SELECT 
DISTINCT in the first place, as it would appear that a normal SELECT 
should do the job just fine.

I can't think of a scenario where the filter query would return more 
than 1 row per issue, and if there were I think it probably means that 
we have an improperly-written join.

Does anyone know or recall the reason for having the DISTINCT in the 
first place ? Are there scenarios that I have not thought about where it 
would be necessary ?

D


[1] http://www.mantisbt.org/bugs/view.php?id=16259#c37901