Associative Array: reasonable limits?

[Charles Hixson]

I'm contemplating an associative array that will eventually grow to be 
an estimated 64KB in size, assuming it's about half full.  It would then 
be holding around 90,000 entries.  Is this reasonable, or should I go 
with a sorted array, and do binary searches?  I estimate that binary 
searches would average around 15 accesses/hit, but that's still a lot 
faster than disk access.  The array would be nearly full, so there would 
be less wasted space, but, of course, insertions would become quite 
expensive.  (Deletions aren't expected.)  In either case the keys would 
be fixed length character arrays, and the values would also be simple 
structs without reference types (so the garbage collector could pretty 
much ignore things).

FWIW I'm expecting this array to be around the entire time the program 
is running, but it would probably be rolled out most of the time, as 
frequently accessed items would be pulled into a much smaller structure, 
and if I go with the array rather than the hash table I may only do 
updates as a batch.  (Since it's linear with the size of the array, but 
essentially ignores the number of items being added.)

My temptation is to go with the hash table...but I'm not sure of the 
underlying mechanics.

--
Charles Hixson