As a bonus, most SQL databases will let you join against the same table multiple times, allowing you to query for nodes with some combination of characteristics: 
SELECT n.*
  FROM nodes n, meta_data md1, meta_data md2
 WHERE md1.name = ?
   AND md1.value = ?
   AND n.id = md1.node_id
   AND md2.name = ?
   AND md2.value = ?
   AND n.id = md2.node_id
 ORDER BY 1

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(Check the documentation for your database software to confirm that this is supported and identify any idiosyncratic syntax that you may have to comply with.)

For what it's worth, I use a similar structure to store clinical records data for a hospital's psychiatry department, and after a bit of time spent examining MySQL's query plans and adjusting the indexes, have found the performance of this type of query to be acceptable, even with tens of thousands of entries.

In reply to Re: Re: Querying Meta Data by simonm
in thread Querying Meta Data by eric256

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