Hi, we need to perform fast geo lookups on an index of ~13M places, and were running into performance problems here with SOLR. We haven't done a lot of query optimization / SOLR tuning up until now so there's probably a lot of things we're missing. I was wondering if you could give me some feedback on the way we do things, whether they make sense, and especially why a supposed optimization we implemented recently seems to have no effect, when we actually thought it would help a lot.
What we do is this: our API is built on a Rails stack and talks to SOLR via a Ruby wrapper. We have a few filters that almost always apply, which we put in filter queries. Filter cache hit rate is excellent, about 97%, and cache size caps at 10k filters (max size is 32k, but it never seems to reach that many, probably because we replicate / delta update every few minutes). Still, geo queries are slow, about 250-500msec on average. We send them with cache=false, so as to not flood the fq cache and cause undesirable evictions. Now our idea was this: while the actual geo queries are poorly cacheable, we could clearly identify geographical regions which are more often queried than others (naturally, since we're a user driven service). Therefore, we dynamically partition Earth into a static grid of overlapping boxes, where the grid size (the distance of the nodes) depends on the maximum allowed search radius. That way, for every user query, we would always be able to identify a single bounding box that covers it. This larger bounding box (200km edge length) we would send to SOLR as a cached filter query, along with the actual user query which would still be sent uncached. Ex: User asks for places in 10km around 49.14839,8.5691, then what we will send to SOLR is something like this: fq={!bbox cache=false d=10 sfield=location_ll pt=49.14839,8.5691} fq={!bbox cache=true d=100.0 sfield=location_ll pt=49.4684836290799,8.31165802979391} <-- this one we derive automatically That way SOLR would intersect the two filters and return the same results as when only looking at the smaller bounding box, but keep the larger box in cache and speed up subsequent geo queries in the same regions. Or so we thought; unfortunately this approach did not help query execution times get better, at all. Question is: why does it not help? Shouldn't it be faster to search on a cached bbox with only a few hundred thousand places? Is it a good idea to make these kinds of optimizations in the app layer (we do this as part of resolving the SOLR query in Ruby), and does it make sense at all? We're not sure what kind of optimizations SOLR already does in its query planner. The documentation is (sorry) miserable, and debugQuery yields no insight into which optimizations are performed. So this has been a hit and miss game for us, which is very ineffective considering that it takes considerable time to build these kinds of optimizations in the app layer. Would be glad to hear your opinions / experience around this. Thanks! -- Matthias Käppler Lead Developer API & Mobile Qype GmbH Großer Burstah 50-52 20457 Hamburg Telephone: +49 (0)40 - 219 019 2 - 160 Skype: m_kaeppler Email: matth...@qype.com Managing Director: Ian Brotherston Amtsgericht Hamburg HRB 95913 This e-mail and its attachments may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail and its attachments. Any unauthorized copying, disclosure or distribution of this e-mail and its attachments is strictly forbidden. This notice also applies to future messages.