Factors to consider

• What data types does it support and what are your own requirements for data types ?

• Do you need flexible schema or rigid schema ?

• Is query flexibility important to you ?

• Do you want to store large amounts of data across several machines

• How much important is sata safety (via ACID compliance or something else)

• Do you need Triggers

• Do you need Transactions (for atomicity)

• Do you need Stored Procedures

• How much important is having ability to create Views for you ?

• Can you live without Joins ?

• Do you need Partitioning ?

• Do you need to store only large blobs of data ?

• Do you have enough information about the database requirements (like schema, probable tables, data types etc)