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).
Yes, you can do that. Simply create a Solr schema, that contains all fields necessary for both tables and add another field, that contains the table name. During indexing, add the table name property to the fields you want to index. During searching also always include a query parameter for the table name field.

As an alternative, you can setup multiple instances of Solr. But you should do this only, if we are talking about massive amounts of data here (like millions of table rows).