Re: 32bit vs 64bit ?

Don't be misled by marketing hype. 32 bit is sufficient for most of the current RDBMS requirements. For OLTP big SGAs are useful and the standard rule of thumb is 1% of data size as good starting point. i.e 200GB database would need a 2GB SGA. With 32bits you can have an SGA of nearly 4GB (Solaris 2.5.1) and hence this would support a database of 400GB. There aren't that many users who have requirement currently above this. If you do need more cached than this then the UNIX buffer cache can be as big as 30GB on Sun's new Enterprise servers and this does a passable job of cacheing data! I would also point out that the recent TPC-C results showed Sun could very nearly match a 64 bit machine with just mid range 32 bit Enterprise 5000. (I can remember the exact numbers).

Second, 64 bits isn't particularly useful for TPC-D or decision support as all the database I/O goes through process local memory and not the SGA. This is borne out by the fact that a 32 bit machine (A Sun Enterprise 6000) got better TPC-D results than any of the other published results including MPP machines.

Finally, getting your database into memory is all very well but remember - you have to pay for that memory and it can be quite expensive.

Tim

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