On Tue, Sep 11, 2018 at 11:00 PM Shawn Heisey <apa...@elyograg.org> wrote:
> On 9/11/2018 8:35 PM, John Smith wrote: > > The problem is that the math isn't a simple case of adding up all the row > > counts. These are "left outer join"s. In sql, it would be this query: > > I think we'll just have to conclude that I do not understand what you > are doing. I have no idea what "left outer join" even means, how it's > different than a join that's NOT "left outer". > > I will say this: Solr is not very efficient at joins, and there are a > bunch of caveats involved. It's usually better to go with a flat > document space for a search engine. > > Thanks, > Shawn > > A "left outer join" in sql is a join such that if there is no match in the child table for a given header id, then the child cells are returned as "null" values, instead of the header row being removed from the result set (which is what happens in "inner join" or standard sql join). A good rundown on the various sql joins: https://stackoverflow.com/questions/38549/what-is-the-difference-between-inner-join-and-outer-join
