On Wed, 7 Mar 2007, Josh Berkus wrote:
> "Approximate queries" is something with DSS users *want*. Jim Grey addressed
> this in his ACM editiorial on the databases of the future. It's something
> that *I* want, and if the Greenplum people aren't speaking up here, it's
> because they're not paying atttention.
>
> Now, I don't know if this Skyline patch is our answer for approximate queries.
> Maybe I should pester Meredith about getting QBE free of its IP issues; it
> certainly looked more flexible than Skyline. In either case, the code
> probably needs a complete refactor.
What people want from "approximate queries" is different to this: the
desire is usually to balance run time with level of accuracy/quality (some
times the desire is to have accurate results as well as similar results).
Neither skyline or QBE are about this. The only thing in the spec which
addresses this is 'tablesample'.
Thanks,
Gavin
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
