Tuning Question

Just looking for opinions... I have my own and another DBA I work with has his opinion. Looking for some other opinions...

Some info on setup first...

• SunFire V880 8x900MHz CPUs
• 16Gig Memory
• 3 databases
  • db1 - 360M SGA - 5 Gig allocated space
  • db2 - 1200M SGA - 55Gig allocated space
  • db3 - 1200M SGA - 60Gig allocated space
• all of these SGAs are mostly allocated to db buffers, but all have over 100 meg for shared pool
• all in archive log mode
• nothing else runs on this machine except these 3 Oracle databases and only DBAs login
• all version 8.1.7.4

Scenario: Suppose you have a small table less than 1Meg (.82) that is queried 140,000 times a day on db2. The table currently has no index, and the query runs in less than 1 second (100Msecs) when the server is idle (no other activity).

Question: Would you put an index to improve the 1 query to improve averall system usage?

My opinion is the table is so small , if it isn't always cached, then it should be forced to be cached.

Other DBA's opinion is to add a combo-index on the 2 columns queried in this 1 query.

Note: I am not sure of other usage of this table. There could be other querys on other columns or a lot of inserts ... not sure right now.

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