Re: Query Help

Thank you. I have it working now. What if I have two attributes on the 
MyElement named MyId and MyFlag and I want to get the MyId values for 
all entries where MyFlag=1? That's really what I ultimately want.

Liz

Vadim Gritsenko wrote:
> On Jul 23, 2010, at 11:43 AM, Liz Glasser wrote:
>
>   
>> I have a ton of records in my xindice database that look like:
>> <MyRootElement myId="...">.....</MyRootElement>
>>
>> I need the most efficient way to get a list of all values for myId. How can I best do this?
>>
>> Basically if this was a relational database and I had a table called MyRootElement, I'd do "select myId from MyRootElement". I need a xindice equivalent.
>>     
>
> Hey Liz,
>
> The query you are looking for is "/MyRootElement/@myId". Using command line you can query it like this (replace /db/my/collection with path to your collection):
>
>   xindice xpath -c /db/my/collection -q /MyRootElement/@myId
>
> Results should look like:
>
>   <xq:result xmlns:xq="http://xml.apache.org/xindice/Query" myId="value" xq:col="/db/my/collection" xq:key="MyDocument1" />
>   ...
>
>
> Now, if only some % of documents in this collection contain this root element/attribute, then you can speed that query up by build an index on the element/attribute pair. Index will allow query engine to skip documents which do not have that element/attribute pair. Index also helps if you want to find a document by value of the myId attribute. Command to build the index looks like:
>
>   xindice add_indexer -c /db/my/collection -n MyRootElementMyId -p MyRootElement@ myId
>
>
> OTOH, if all documents have the same structure, then in order to extract all of the values, query engine will have to iterate through all of the documents in the collection - and index will be of no help.
>
> Hope that helps.
>
> Vadim
>
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