launchpad-dev team mailing list archive

[Jeroen Vermeulen <jtv@xxxxxxxxxxxxx>]

On 2011-09-27 21:13, Abel Deuring wrote:

> yes, this is the core of what StormRangeFactory is intended to improve:
> Get rid of the need to count larger result sets for OFFSET and SELECT
> count(*). (The latter is replaced by an estimation. It might make sense
> to change the text "15->20 of 234 results" with something like "15->20
> of approximately 234 results" -- I suspect that the estimated result
> size can be drastically wrong for non-trivial queries.)

Oh yes, if it's based on the database's stats then it's going to be 
wildly unreliable for complex queries.  But potentially quite reliable 
for simple ones, if you can tie the estimate directly to a number that 
is kept as a statistic.


Jeroen