15 feb 2009 kl. 16.27 skrev Joel Halbert:

Is there any practical limit on the number of fields that can be
maintained on an index?

My index looks something like this, 1 million documents. For each group
of 1000 documents I might have 10 indexed fields. This would mean in
total about 10000 fields. Am I going to run into any issues here?

The index in Ram based.


There is a resource cost to handle identical term values in several fields rather than keeping them in a single field as there is one index per field. You might however save CPU at query time by dividing them up in multiple fields as a field index would be smaller and thus faster to navigate. But at the same time Lucene is more or less logarithmic when it comes to speed so you might actually save both speed and resources by using the same field if you can.

I don't think there will be a problem. A million documents might however consume a lot of RAM. Did you measure how much slower it is on FS? The difference really should not be that great, especially when the index is that large. Also, reports (including my own) indicate that running the index on SSD is as fast as running in RAM so you might want to look in to how much bang for the buck you get by hosting in RAM rather than on SSD.

Hope this helps,

       karl

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