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From Toke Eskildsen ...@statsbiblioteket.dk>
Subject Re: Right memory for search application
Date Thu, 29 Apr 2010 07:47:21 GMT
On Wed, 2010-04-28 at 16:57 +0200, Erick Erickson wrote:
> And you can extend this ad nauseum. For instance, you could use 6
> fields, yy, mm, dd, HH, MM, SS and have a very small number of
> unique values in each using really tiny amounts of memory to sort down
> to the second in this case.

A reference to a String takes up 4 or 8 bytes, depending on JVM and
setup. When doing String-based sorting in Lucene, there will be a
reference for each document for each sort-field. With 18M documents,
this will be at least 18M * 4 bytes * 6 = 432 MB. Plus the negligible
amount of String objects. It is less than the previously estimated
1.2GB, but still worth noting.

- Toke


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