Thanks you and your precious comments again!

I have to state my task formally:

My data files consist of two files transaction_info_file (TranactionID, ... personID ...) and Tranaction_detail_file (TranactionID, productID...) and they are related by one-to-many relationship. My task is to do some JOIN and SELECT/COUNT from those data. It sounds very simple before and I put everything in database with fine tuned indexes. However, size does matter.

Now I use Perl to something like Hash-Join, scan all event_info_file once, put eventid in a seen-hash, then extrieve records from event_detail_file by looking up seen-hash.

I've tried:

Hash-Join solution is the best among them though still slow. I understand it would be easier if I have larger storage and a well-designed datawarehouse. Is it a must if I only want to know some simple questions such as who is the best buyer ? how many customers do i have ? (this is not a routine work as those bussiness user)

by the way, i've tried pre-allocated method such as keys %hash=10_000_000,however, it seems no performance gain. Maybe this function is OS-dependent that it does not work on my windows-activeperl platform.

In reply to Re^2: How do I measure my bottle ? by cbrain
in thread How do I measure my bottle ? by cbrain

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