If I set NO_SUBQF=1 then select works correctly still in Linux IDS 9.40.UC6
I don't find any documentation about this environment variable. How does this variable work ?
-----Messaggio originale-----
Da:
informix-list-bounces@iiug.org
[mailto:informix-list-bounces@iiug.org]Per conto di
matthias.butterweck@comline.de
Inviato: venerd́ 3 marzo 2006 8.43
A:
informix-list@iiug.org
Oggetto: Re: R: Problems using "EXISTS"
Thanks you for replying!
So far the problem only occurs on one server with version 9.40.FC3XF.
The query runs ok on another server with the exact same version
9.40.FC3XF and on another one with version 9.21.FC4.
> Clearly, the query can readily be written without an EXISTS clause -
> and this may provide a temporary workaround.
Unfortunately it doesn't, because in our real life application there
may be very many item rows with key="Key1" and value="Value1", and we
only need the distinct child.id_folder values. If we add "DISTINCT" to
the select list, the query runs forever (well, almost).
Upon further investigation we found out that by setting the environment
variable NO_SUBQF, the problem goes away.
Looking at the explain plan of the query without NO_SUBQF we find
4) c0111.item: INDEX PATH (First Row)
Filters: (c0111.item.value = 'Value1' AND c0111.item.key = 'Key1'
)
We think that maybe there lies the problem (bug in the optimizer)
In conclusion the problem is solved somehow by setting NO_SUBQF, but we
have to do this now in all our application environments for all our
customers until the bug is fixed.
Kind regards
Matthias
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