Alban
Thanks for your help, your suggestion worked.
I need another xpath expression to find any Attribute with Name ="xxxx" under the Attributes node. (not just if it is in a specific position)
see query below.
How do I create an index for this xpath expression ?
Thanks
Chris
SELECT * FROM time_series
WHERE array_upper((xpath('/AttributeList/Attributes/Attribute[Name="xxxxx"]', external_attributes)),1) > 0
On Sun, Mar 7, 2010 at 1:11 PM, Alban Hertroys
<dalroi@solfertje.student.utwente.nl> wrote:
On 7 Mar 2010, at 11:02, Chris Roffler wrote:
> I still have some problems with my xml index
>
> CREATE INDEX xml_index
> ON time_series
> USING btree
> ((
> (xpath('/AttributeList/Attributes/Attribute/Name/text()', external_attributes))[1]::text));
>
> When I run the following query the index is not used :
>
> select id from time_series where
> array_upper(
> (xpath('/AttributeList/Attributes/Attribute[Name="Attribute122021"]', external_attributes))
> , 1) > 0
>
> Any Idea on how to configure the index ?
You seem to want to test for the existence of nodes with a specific name, maybe this is what you're looking for?:
SELECT id FROM time_series t1 WHERE EXISTS (
SELECT 1
FROM time_series t2
WHERE (xpath('/AttributeList/Attributes/Attribute/Name/text()', external_attributes))[1]::text = ('Attribute122021', external_attributes)
AND t2.id = t1.id
);
It's just a guess at what you're trying to do, so I may very well have gotten it wrong. The important part is that you need to use the expression you indexed in your where clause, or the database has no idea you mean something similar as to what you indexed.
Alban Hertroys
--
If you can't see the forest for the trees,
cut the trees and you'll see there is no forest.
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