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From Mauricio Scheffer <>
Subject Re: SOLR vs SQL
Date Wed, 02 Sep 2009 12:28:05 GMT
This article explains in-depth why calculating facets is not practical in
pure SQL:


On Wed, Sep 2, 2009 at 5:30 AM, gwk <> wrote:

> Fuad Efendi wrote:
>> "No results found for 'surface area 377', displaying all properties."
>> - why do we need SOLR then...
> Hi Fuad,
> The search box is only used for geographical search, i.e.
> country/region/city searches. The watermark on the homepage indicates this
> but the "search again" box on the search results page does not, I'll see if
> we can fix that.
> We use Solr not so much for the searchbox, which to be honest was an
> afterthought. But we do use Solr for faceting. Honestly, the thought of
> writing an SQL query which calculates all these facet counts every time a
> search parameter is changes gives me a headache, I don't think it's possible
> to do it in one query (although maybe, but I don't think anybody would want
> to maintain it). As for performance, every nontrivial database/search engine
> is affected by dataset for all but the simplest queries, and in my tests
> Solr trumps Mysql by a huge margin for our use case. We use a database to
> store our data in a somewhat normalized way, which is good for data
> consistency, but not so good for retrieval speeds. This is what makes Solr
> so useful for us, we can index all data in denormalized form with all data
> for a property in one record. While the (sql) database remains authoritative
> Full-text search is only one part of Solr, while an important part it isn't
> the only reason for using Solr. In our case, since we provide support for
> multiple language we try not to store textual descriptions but every facet a
> property can have. This gives us exactly the data needed to perform faceting
> but not so much on the full text search (which is used mind you, to find
> suggestions when you use the search box).
> Regards,
> gwk

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