Re: The term "Transactions Per Second"

Ramzi BAROODY (rbaroody_at_cs.mcgill.ca) wrote:

: If someone says that a certain server can perform 282 TPS (transactions
: per seconds) under Oracle 7, then what exactly does this measure indicate?
: What is considered as a transaction in this case?
 

: Ramzi

Hi Ramzi.

A transaction is a logical unit of work which is all the database updates that are performed between the beginning of a transaction and the COMMIT. Some transactions can be long and others short. For the sake of illustration let's say that a really fast operator can complete a transaction in 60 seconds. This means that 60 operators would be able to processs one TPS. In order to create 280 transcation in a second, there would have to be about 17,000 concurrent users!

What you are probably being told refers to some cooked up becnhmark which Oracle and other RDBMS vendors run called the TPC-A benchmark. It is a benchmark designed by RDBMS vendors to make their products look far more capable than they really are. The new TPC-C benchmark gives more realistic results but the TPC committee of RDBMS vendors changed the metric so that it now reads as TPM (transactions per minute). These guys are really something else.

In my experiences, the Unix RDBMSs normally handle about 1 - 5 TPS. In rare occassions they go higher. In order to get over 100 TPS you really need to look at specialized RDBMSs like Tandem Non Stop SQL or some mainframe DBMSs.

If you want to read more about TPC benchmarks, David McGoveran has an excellent discussion of it in the February issue of Network Computing. Basically he finds it a highly politicized and misleading benchmark. I agree. BTW, one consultant who wrote a stinging report concerning the Oracle "discrete transaction" which Oracle used to get their exaggerated results is currently being sued by Oracle.

• Rich

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Richard Finkelstein                        Voice: 312-549-8325     
Performance Computing, Inc.                Fax: 312-549-4824 
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