what are the de-merits of Data base managments systems?

Answer 1

The De-merits are:
It is prone to hackers and even the best security system will not prevent users from leaking out sensitive information.
Also, if the database is down or there's a power cut, it results in loss of time and money, but this can be curbed if you have good database support analysts.
But surely the merits far exceed the de-merits.

Answer 2

head to head, sequentially reading a relational database can be slower than reading the same data from a hierarchical database.

A few years ago, I was involved in a disagreement at a large finacnial services company - between DLI & DB2 DBA's.

To settle the issue, a large sample set of data was identified. The DLI DBA built a database to hold the data and then loaded it. He then ran a batch process to sequentially read all the data. No matter how hard he tried, the DB2 DBA couldn't match the time.

Fortunately, sequential reads are not the primary use made of databases, so this really not a huge problem (except with some datamart & data wharehouse & other (database synch) processes).

BUT - beware of anyone who says Oracle is the answer - Oracle is pretty darn good. But Oracle is in it's own fight with DB2 (and DB2 is (finally) catching up) - and DB2 often runs on a far more powerful platform, so tends to have the edge in grunt processing. Oracle does do a good job for intermediate & short-term storage for data that doesn't need major manipulation - so it can be useful for web services, where an EIS DB like DB2 would have extra overhead.

Answer 3

The DBMS has a number of advantages as compared to traditional computer file processing approach. The DBA must keep in mind these benefits or capabilities during designing databases, coordinating and monitoring the DBMS.

Answer 4

Demerits??? Do you mean short comings???

As long as you're using Oracle, there aren't any. You do need people who know how to write sql and a DBA that knows how to manage the system.