: ".../select?q=*&sort=evalDate+desc,score+desc&start=0&rows=10" : : This query takes around 5 seconds to complete. : : I changed the query to the following; : : ".../select?q=[* TO NOW]&sort=evalDate+desc,score+desc&start=0&rows=10" : : The query now returns in around 600 milliseconds. : : Can any one help with explaining why [* TO NOW] has had such a big effect?
Short answer: because these are compleltey differnet queries, and match completley differnet sets of documents, using completley different logic. "q=*" means "a prefix query against the default search field where the prefix is the empty string" and it -- so assuming your default search field is called "text" q=* is equivilent to q=text:* that will match all docs that have some value indexed in the text field. finding all of those docs means iterating over every term in that field, and tracking every document associated with those values -- the default search field typically has *lots* of indexed terms conversly, "q=[* TO NOW]" means "a range query of the default search field for all terms that are less then 'NOW'". for a date field "NOW" is converted to the current time, but unless your default search field is a date field that's not relevant. more then likely "NOW" is just interpreted as the string "NOW" (or maybe "now" if your default serach field is lowercased) and that query just matches all the terms that are alphabetically before it. all terms alphabeticly sorted before "NOW" are less then all terms, so the second query is basically garunteed to be faster then the first ... and most likely matches a much smaller set of documents. -Hoss -- http://lucenerevolution.org/ ... October 7-8, Boston http://bit.ly/stump-hoss ... Stump The Chump!
