The database is very good in answering queries that look for an exact match such as this:
select * from Users where Name = 'ayende'
But it requires a lot more work when you are using a like, such as this query:
select * from Users where Name like 'ayende%'
In many cases, the database can still optimize this query, and assuming that you have an index on this field, use the index.
But when things are drastically different when you have a query that checks for contains:
select * from Users where Name like '%ayende%'
Or using ends with:
select * from Users where Name like '%ayende'
The problem is that the databases cannot use an index for this sort or query, and it is force to issue a full table scan, inspecting each of the values in the database for a match. This tends to be very inefficient process.
You should carefully consider whatever you should use this feature, and if you really need to support ends with and contains queries, you should consider using either the database' own full search indexing, or using an external full text search option, such as Lucene or Solr.