Question: I have two tables contacts and inventory. These two tables are not related. I want to index these two tables and search using Solr.

Is this possible?

Answer: 
If some part of your application needs to search for contacts, and another one needs to search in the inventory, create two separate indices. Storing wildly different data in the same index is almost never a good idea, it complicates things unnecessarily. As the [Solr wiki wisely says](http://wiki.apache.org/solr/SchemaDesign):

> 
> The more heterogeneous (different
>  kinds of data) you have in one field
>  or in one index, the less useful it
>  is.
> 
> 
> 

You don't need to have multiple Solr instances to accomodate multiple indices, you can easily manage this with [multi-core](http://wiki.apache.org/solr/CoreAdmin).
I found a very helpful answer to this question [here](http://www.lucidimagination.com/blog/2011/02/12/solr-powered-isfdb-part-4/), including some guidance on using "multiple indexes" vs. "multiple document types in one index". The post also links to example code on github that I found very useful.