On Jun 7, 2007, at 12:38 PM, David Metzler wrote:
If that's true, then the overhead of a JOIN on an empty table would be significantly different than the join on a table that has a million rows in it, regardless of the filter criteria, yes?
no: 1) {node_revisions} *ALWAYS* has at least 1 record for any given node. that's where title, body, etc are stored. please read the schema if you have further questions. therefore, the only site with an empty {node_revisions} table is the site with no nodes at all. 2) {node_revisions} has an index on nid, and we always JOIN on nid. by and large, the cost of this JOIN is constant, regardless of the # of rows in the table, since the JOINs basically always use the index. cheers, -derek (dww)