Chad,
On 1/30/07 6:13 AM, "Chad Wagner" <[EMAIL PROTECTED]> wrote:
> Sounds like an opportunity to implement a "Sort Unique" (sort of like a hash,
> I guess), there is no need to push 3M rows through a sort algorithm to only
> shave it down to 1848 unique records.
>
> I am assuming this optimization just isn't implemented in PostgreSQL?
Not that it helps Igor, but we've implemented single pass sort/unique,
grouping and limit optimizations and it speeds things up to a single seqscan
over the data, from 2-5 times faster than a typical external sort.
I can't think of a way that indexing would help this situation given the
required visibility check of each tuple.
- Luke
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