Kamlesh,

You can read complete information on the subject by searching the Knowledge
Base at http://www.ibphoenix.com

Look for anything containing "OIT" or "OAT".

Mainly :
- KB 129 : "Definition of OIT"
- KB 128 : "Moving the Oldest Interesting (OIT) and the Oldest Active (OAT)
transactions along."

[..]

> what can be said long running transaction
> i mean how long is long and with how many users and how it affects ,
> will my select queries get slow down ?(how much) ?

Actually time is not the issue. An active transaction gets "longer" as the
number of transactions started after it increases.

[..]

> does it affects performance of transactions aginst that perticular tables
> (on which
> transaction is running) or
> does it affect performance for whole database for all the tables

A big OAT-OIT difference will increase the amount of infos *each* starting
transaction will have to recopy from the TIP. So, every transaction will be
affected, not only particular tables.

Regards.

--
Jerome