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Can you suggest me any CPAN modules to search on a large sorted file?
The file is a structured data about 15 million to 20 million lines, but I just need to find about 25,000 matching entries so I don’t want to load the whole file into a hash.
Thanks.
A scan over the whole file may be the fastest way. You can also try File::Sorted, which will do a binary search for a given record. Locating one record in a 25 million line file should require about 15-20 seeks for each record. This means that to search for 25,000 records, you would only need around .5 million seeks/comparison, compared to 25,000,000 to naively examine each row.
Disk IO being what it is, you may want to try the easy way first, but File::Sorted is a theoretical win.