Help with value index

Question

Hi,
We need some help getting our queries to join on V() type indexes, so we think.
Here is our situation: We are on DBXML 2.2.13, and not quite ready to upgrade.
We are trying to do a join of 2 or sequences each 5000 in length.
Based on our reading of the query plan, the joins are not using the V(...) type index on both sides of the join.
One side will use a V() index, the other uses a P() regardless of the indexe(s) we apply.
We used double data type on the index type because of another posting, but we we get the same results regardless of the datatypes used in out index(s)
The @patient-ref and @id values are all positive integer values.
We've re-arranged the query, we've tried many different datatypes on the query.... Help!
The questions are:
a) are we on to the correct optimization strategy, and
b) please help us how to figure out how to get the right type of indexs applied.
Thanks...
dbxml> reindex system.dbxml n
dbxml> list
Default Index: node-attribute-equality-double
Index: unique-node-metadata-equality-string for node {http://www.sleepycat.com/2002/dbxml}:name
2 indexes found.
dbxml> queryplan 'for $pid in collection()/reports-catalog/report/@patient-ref where $pid = collection()/patient-index/patient/@id return $pid'
<XQuery>
<FLWOR>
<ForBinding name="pid">
<Navigation>
<QueryPlanFunction result="collection" container="system.dbxml">
<OQPlan>P(node-attribute-equality-double,prefix,@patient-ref)</OQPlan>
</QueryPlanFunction>
<Step axis="child" name="reports-catalog" nodeType="element"/>
<Step axis="child" name="report" nodeType="element">
<OQPlan>P(node-attribute-equality-double,prefix,@patient-ref)</OQPlan>
</Step>
<Step axis="attribute" name="patient-ref" nodeType="attribute"/>
</Navigation>
<Where>
<Navigation>
<QueryPlanFunction result="collection" container="system.dbxml">
<RQPlan>V(@id,=,'[to be calculated]')</RQPlan>
</QueryPlanFunction>
<Step axis="child" name="patient-index" nodeType="element"/>
<Step axis="child" name="patient" nodeType="element">
<RQPlan>V(@id,=,'[to be calculated]')</RQPlan>
</Step>
<Step axis="attribute" name="id" nodeType="attribute"/>
<DbXmlCompare name="equal">
<Variable name="pid"/>
</DbXmlCompare>
</Navigation>
</Where>
</ForBinding>
<Variable name="pid"/>
</FLWOR>
</XQuery>

Answer 1

I did try the node-attribute-equality-string index before, but I must have left on my node-element-presence-none index, because now, I'm getting what looks like a much more improved query using the string index and NOT using the node-element-presence-none index.
dbxml> run test.xq
Default Index: node-attribute-equality-string
Index: unique-node-metadata-equality-string for node {http://www.sleepycat.com/2
002/dbxml}:name
2 indexes found.
Adding default index type: node-attribute-equality-string
Container reindexed: chb-system.dbxml
5000 objects returned for eager expression '
for $pid in collection()/reports-catalog/report/@patient-ref
where   $pid = collection()/patient-index/patient/@patient-ref
return
        $pid
Time in seconds for command 'query': 2.438
dbxml> run test.xq
Default Index: node-attribute-equality-string
Index: unique-node-metadata-equality-string for node {http://www.sleepycat.com/2
002/dbxml}:name
2 indexes found.
Adding default index type: node-attribute-equality-string
Container reindexed: chb-system.dbxml
<XQuery>
  <FLWOR>
    <ForBinding name="pid">
      <Navigation>
        <QueryPlanFunction result="collection" container="chb-system.dbxml">
          <OQPlan>P(node-attribute-equality-string,prefix,@patient-ref)</OQPlan>
        </QueryPlanFunction>
        <Step axis="child" name="reports-catalog" nodeType="element"/>
        <Step axis="child" name="report" nodeType="element">
          <OQPlan>P(node-attribute-equality-string,prefix,@patient-ref)</OQPlan>
        </Step>
        <Step axis="attribute" name="patient-ref" nodeType="attribute"/>
      </Navigation>
      <Where>
        <Navigation>
          <QueryPlanFunction result="collection" container="chb-system.dbxml">
            <RQPlan>V(@patient-ref,=,'[to be calculated]')</RQPlan>
          </QueryPlanFunction>
          <Step axis="child" name="patient-index" nodeType="element"/>
          <Step axis="child" name="patient" nodeType="element">
            <RQPlan>V(@patient-ref,=,'[to be calculated]')</RQPlan>
          </Step>
          <Step axis="attribute" name="patient-ref" nodeType="attribute"/>
          <DbXmlCompare name="equal">
            <Variable name="pid"/>
          </DbXmlCompare>
        </Navigation>
      </Where>
    </ForBinding>
    <Variable name="pid"/>
  </FLWOR>
</XQuery>
Time in seconds for command 'queryPlan': 0.188