On 3/21/2013 4:05 AM, Per Steffensen wrote:
Can anyone else elaborate? How to "activate" it? How to make sure, for sorting, that sort-field-value for all docs are not read into memory for sorting - leading to OOM when you have a lot of docs? Can this feature be activated on top of an existing 4.0 index, or do you have to re-index everything?
There is one requirement that may not be obvious - every document must have a value in the field, so you must either make the field either required or give it a default value in the schema. Solr 4.2 will refuse to start the core if this requirement is not met. The example schema hints that the value might need to be single-valued. I have not tested this. Sorting is already problematic on multi-valued fields, so I assume that this won't be the case for you.
To use docValues, add docValues="true" and then either set required="true" or default="<somevalue>" on the field definition in schema.xml, restart Solr or reload the core, and reindex. Your index will get bigger.
If the touted behavior of handling the sort mechanism in OS disk cache memory (or just reading the disk if there's not enough memory) rather than heap is correct, then it should solve your issues. I hope it does!
Thanks, Shawn
