multi-user database design

How do the likes of Amazon and Hotmail etc (anyone with loads of users) design their databases ? Would they set up a new database user for each of their customers and thus have literally thousands of users accessing their database at a time. Or would they have one or two "power" users to access their databases and retrieve all of the data and then pass it back to each individual user ?

Also, would they use persistent db connections (with Apache and mod_perl or something) to increase speed or would they try and save some memory and just make a new connect to the database each time the users request information? I can imagine that persistent connections would limit the number of concurrent users possible due to memory usage. Thanks
Richard

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Before you buy. Received on Tue Jan 18 2000 - 18:00:36 CST