On 4/25/2013 8:17 AM, Gustav wrote: > Are these two methods functionally different? Is there a performance > difference? > > Another though would be that, if using join tables in MySQL, using the SQL > query method with multiple joins could cause multiple documents to be > indexed instead of one.
They may be equivalent in terms of results, but they work differently and probably will NOT have the same performance. When using nested entities in DIH, the main entity results in one SQL query, but the inner entities will result in a separate SQL query for every single item returned by the main query. If you have exactly 1 million rows in your main table and you're using a nested config with two entities, you will be executing 1000001 queries. DIH will be spending a fair amount of time doing nothing but waiting for the latency on a million individual queries via JDBC. It probably also results in extra work for the database server. With a server-side join, you're down to one query via JDBC, and the database server is doing the work of combining your tables, normally something it can do very efficiently. Thanks, Shawn
