question on EXPLAIN_PLAN

Hi, guys

The problem belows is really make me confused and gave me big trouble, is there someone can give me some hlep?

I have two databses, same version(oracle 8.1.6),same O/S(win2000), same schema structure, different data(but small difference of size).

and even exactly same explain_plan of my sql query.

But on one database, the cardinality of one PK index access upon one table is 27(cost=2,card=27,bytes=756) (table rows 263758)

and the other is 11706!!!! (cost=3,card=11706,bytes=199002)( table rows 351173).

so, on one DB the sql query took 300ms, one the other, it took 5 seconds!

Any advise is highly appreciated.

thanks,

Kevin Wang
Database Administrator
Vivonet Canada Inc.

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