Question on memory requirement for Oracle 9i and Oracle 10g

Greetings All,

We have one database on a Sun server (Sun Enterprise 450) with Solaris 7. Currently the database runs on Oracle 8.1.7 with the 2GB of memory(RAM). We are estimating for the memory requirement for this database as it will be upgraded to Oracle 9i and then finally to 10g. I am thinking of upgrading the memory from 2GB to 4GB.  

Assuming that same numbers of users will be there when the database is upgraded to 9i and 10g do you think the 4GB of memory is sufficient or for 10g the memory requirement could be more than 4GB.

Thanks,
Ashoke

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