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Is sphinx capable of heavy geo-based services?
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cysin
Name: cysin |
2010-06-04 05:49:27
| reply! I mean lots of geodist queries. I don't know sphinx's performance on geodist queries, seems it computs geo-distance every time. Which is better compared to MySQL's spatial extensions? |
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barryhunter
Name: Barry Hunter |
to: cysin, 2010-06-04 14:51:23
| reply! > Is sphinx capable of heavy geo-based services? Certainly! I use it a lot. It's great. For simple X nearest is many times quicker that mysql. A mysql spatial index performed amiciablly upto about 200,000 rows, but once got more than that sphinx is way quicker. The key is using a hybrid approach, if you do a sort and filter on geodist, then as you mention it has to calculate the spherical distance for all results. But by precomputing 'tiles' basically deviding up your 'world' into a grid, and the saveing the 'tile' as a full text keyword. Then when searching you work out the likly tiles, and search on them. The tile keywords provide broad filtering, cut down drastically on the number of geodist calcs required. But still use geodist to do the final refinement and sorting. The trick is picking a good grid size. Too small, and need to add lots of terms to your search query. Too big, and its not cutting down the number of results being searched much. |
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Scythe
Name: Jeremy |
to: cysin, 2010-06-11 20:30:37
| reply! > I mean lots of geodist queries. I don't know sphinx's performance on geodist queries, > seems it computs geo-distance every time. Which is better compared to MySQL's spatial > extensions? My Site (www.hourdb.com) takes in tons of requests a Sphinx backend. We pre-process things such as zipcodes and city/state combo's into a lat&long pair, and then use Sphinx to order the results. Albeit I'm using a modified version of the geodist calculation in sphinx to improve accuracy, but it's super fast. It's still really quick, and it takes tons of hits everyday. Less than 0.1 ms for worst case scenario. The most important factor is to pre-limit to a fuzzy radius before ordering by distance. |
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