Csaba Nagy <nagy@xxxxxxxxxxxxxx> writes: > [snip] > > The database could be clever and implement the same kind of sampling vacuum > > does. That picks a random sampling of pages from the table without using an > > index. But there's no way to implement the same kind of behaviour from the > > user-visible features. > ... meaning perhaps a new keyword accepted by SELECT, something like > "SAMPLE 1000" ? Which would mean sample records in a 1:1000 ratio ? > Would simplify (and probably speed up a lot) some estimating queries... See: http://www.jlcomp.demon.co.uk/faq/random.html I think the Oracle syntax looks like SELECT * FROM foo SAMPLE (0.1) I don't think I would have picked this syntax but it seems like a better idea to copy the existing practice rather than invent a new one. There are some details, like what to do when there's a WHERE clause or joins. Oracle disallows joins entirely and I'm unclear what the best thing to do about where clauses would be. -- greg ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
