Eric Sun wrote:
>My question is, are these database sizes normal (i.e. are other people
>programming with such large databases?). I ask this because I am having
>some trouble with going through each record for the first 500 records and
>then taking the foreign key to match a record in the second database. This
>is taking about 15-20 minutes to go through it all. Is it because of the
>database sizes or because of my limited knowledge with database and the
>searching capability that Palm comes with?
When you say "taking the foreign key", are you referring to a record unique ID or
record number (index) or something else? Finding a record given its unique ID requires
a linear scan. That means that the operation you're describing is going to get very
slow: O(n squared). If, on the other hand, you used record numbers to get from one
database to the other, then each access is nearly constant time. Of course, if you
reference records by their index, you'll need to update the references whenever you
insert a new record, and that might be too slow, depending on the sort order of the
database and the frequency of insertions. You might want to use a cache approach where
each record in the first database refers to records in the second database using both
a unique ID _and_ a record number. You try the record number first, and if it has the
right unique ID, you're done. If not, you find the record by unique ID and update the
record number. Again, this will only be efficient if insertions are rare. It isn't
easy to come up with a design that works well with lots of data. Hopefully some of
these ideas can help you come up with a more efficient design for your problem.
--
Peter Epstein
Palm Inc. Developer
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