| From: | "Chad Wagner" <chad(dot)wagner(at)gmail(dot)com> |
|---|---|
| To: | "Luke Lonergan" <llonergan(at)greenplum(dot)com> |
| Cc: | "Simon Riggs" <simon(at)2ndquadrant(dot)com>, "Igor Lobanov" <ilobanov(at)swsoft(dot)com>, "Richard Huxton" <dev(at)archonet(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Querying distinct values from a large table |
| Date: | 2007-01-30 15:03:03 |
| Message-ID: | 81961ff50701300703r538cfd58o511ef68ee90a90e5@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On 1/30/07, Luke Lonergan <llonergan(at)greenplum(dot)com> wrote:
>
> 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.
Was that integrated back into PostgreSQL, or is that part of Greenplum's
offering?
I can't think of a way that indexing would help this situation given the
> required visibility check of each tuple.
>
I agree, using indexes as a "skinny" table is a whole other feature that
would be nice.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Luke Lonergan | 2007-01-30 16:34:03 | Re: Querying distinct values from a large table |
| Previous Message | Luke Lonergan | 2007-01-30 14:56:57 | Re: Querying distinct values from a large table |