On Wed, Feb 10, 2010 at 6:25 PM, Paul InterlockInfo <[email protected]>wrote:
> And if I could ask (this is a RBase sql I think), what advantage would > there be in opting to avoid using a index? I always assumed if it is > indexed then RBase would use the index and if not, well it wouldn’t. But > would there be a reason to avoid the index? > > Paul, You would rarely opt to avoid using an index. The rare circumstance would be a query with many conditions in the WHERE clause, and where R:BASE's query optimizer was not automatically picking the best index. You can force it to go on to what it would consider the second-best index by putting the first value (not the whole condition, but the value) in parentheses. I have used this with multi-table queries (more than 5 tables), with MANOPT ON, as part of my way of forcing R:BASE to pick my favorite indexes rather than it's own favorites. I think there were some changes in the query optimizer math results between 7.6 and 8.0 or 9.0 (32) and 9.0 (64), because I had to rewrite just a few queries to get back to speedy results. Bill
