Hi Mansi,

> I am storing deeply nested hierarchal data in XML files. Simply put, most of
> my queries are going to be relative (For e..g //@name). So, I am assuming it
> would be a huge performance hit. Specially, when I know each "ID" will most
> definitely have multiple XML documents. Correct me, if I am wrong here.

Usually, one identifier (ID) exists to reference one data entity
(document, row, etc.). You say that more than one document will be
assigned to a single ID, so you seem to work with 1:n relationships.
For what does your ID stand for?

The notion of tables stems from the relational database world. In XML,
you work with documents and collections, so it's a well-established
procedure to reference documents by their database path. 1:n
relationships can e.g. be represented in another database, which would
contain a document with the following structure:

  <docs>
    <doc id='0'>a.xml</doc>
    <doc id='0'>b.xml</doc>
  </docs>

A query like the following one could be used to address these documents:

  for $doc in db:open('db-ids')//doc[@id = '0']
  return db:open('db', $doc)

If your id database is indexed, access will be very fast (within
fragments of milliseconds).

I agree it takes some time to understand the logics that I sketched
out here, but once you are into it, it works out perfectly fine.

Hope this helps
Christian