Using mmap will give you the same memory sharing effect as reading everything in one process then forking, as well as being easier to manage, somewhat more efficient to read, and making it easier for your OS to manage the memory (data is only paged in as its needed, and the system's buffer cache can just drop pages if it needs the memory, and get it back from the disk later).

Another possibility is to steal an idea from dbz, which indexes a fixed format text file by using the index values as the keys, and the file offset of the start of the record as values. This is fairly straightforward to do with Berkeley DB. A few well-chosen indexes can make a huge difference, without requiring a full rewrite into a relational database.

So if you used mmap and a dbz-style index together, you'd get the file offset from the DB, then use substr to inspect the mmap'd data at that location.

In reply to Re: Speeding up data lookups by sgifford
in thread Speeding up data lookups by suaveant

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