Re: [bdbxml] Space Time Complexity - Performance issues

Manish,

These are large, open-ended questions.  It's possible
to provide information, but not precise numbers.


> Hi all
> I wanted to know what is the space time complexity (or performance  
> limits) for
> 1. Querying across a container with n documents (Indexed)

With the proper query and index, this may be resolved with
a single index lookup operation (btree lookup) and fetching
of the target document(s).
In general, a well-written query with a good index will take
time/space proportional to the number of results.

Without a proper index and/or query, this could iterate through
the entire container, examining each document.

> 2. Querying across a container with n documents (non-Indexed)

Best-case, this is proportional to the number of documents.  A nasty
query can be very slow.

> 3. Cross-querying across 2 containers having m and n documents  
> (Indexed)

This is close to the same as (1) with good indexes, except there
will be 2 index lookups (one per container), not one.

> I want to know the theoretical limits of these queries. Also, it wd  
> be great if you can fwd me some experimentation values etc. or any  
> other documents which provide info abt the theoretical limits of  
> querying, indexing, and population.

The limits, theoretical and not, vary widely with the queries involved.
Even with good indexes, it's possible to construct a query that exceeds
time/space available.

Some hard limits in the current product:
     o document IDs are 32-bit, so that limits number of documents in  
a container.
     o there are no hard limits on number of containers
     o size of a container is limited by the file system's maximum  
file size,
     which is platform-specific.

Regards,

George



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