NOT Equal

An excellent comment/question by mdinh made me realise my demos in Part I might be a little extreme in returning 0 rows and perhaps give the false impression that Not Equal conditions are only considered or applicable if no rows are returned. This is not the case and with the bitmap index now considered with Not [...]

Way back, I previously discussed how the CBO will simply ignore any possible indexes when determining the best execution plan involving a NOT EQUAL(<>) condition, even if an index might in theory provide the most efficient access path. Oracle just assumes that the vast majority of rows are likely to be returned and so doesn’t even [...]