On Mon, Sep 19, 2005 at 10:16:36PM -0400, Bruce Momjian wrote:
Added to TODO:
* Allow DISTINCT to use hashing like GROUP BY
3 lines above we have...
Consider using hash buckets to do DISTINCT, rather than sorting
This would be beneficial when there are few distinct values.
Can you
Jim C. Nasby wrote:
On Mon, Sep 19, 2005 at 10:16:36PM -0400, Bruce Momjian wrote:
Added to TODO:
* Allow DISTINCT to use hashing like GROUP BY
3 lines above we have...
Consider using hash buckets to do DISTINCT, rather than sorting
This would be beneficial when there are few
On Tue, Sep 20, 2005 at 05:05:05PM -0400, Bruce Momjian wrote:
Jim C. Nasby wrote:
On Mon, Sep 19, 2005 at 10:16:36PM -0400, Bruce Momjian wrote:
Added to TODO:
* Allow DISTINCT to use hashing like GROUP BY
3 lines above we have...
Consider using hash buckets to do
Jim C. Nasby wrote:
What do these URL's have that the current TODO does not?
* Consider using hash buckets to do DISTINCT, rather than sorting
This would be beneficial when there are few distinct values. This is
already used by GROUP BY.
Maybe it's just me, but the recent
On Tue, Sep 20, 2005 at 06:45:07PM -0400, Bruce Momjian wrote:
Jim C. Nasby wrote:
What do these URL's have that the current TODO does not?
* Consider using hash buckets to do DISTINCT, rather than sorting
This would be beneficial when there are few distinct values. This is
I was wondering whether it is possible to teach the planner to handle
DISTINCT in a more efficient way:
em=# explain select distinct lastname from import.testtest;
QUERY PLAN
On Mon, 2005-19-09 at 16:27 +0200, Hans-Jürgen Schönig wrote:
I was wondering whether it is possible to teach the planner to handle
DISTINCT in a more efficient way:
[...]
Isn't it possible to perform the same operation using a
HashAggregate?
One problem is that DISTINCT ON is defined to
=?ISO-8859-1?Q?Hans-J=FCrgen_Sch=F6nig?= [EMAIL PROTECTED] writes:
I was wondering whether it is possible to teach the planner to handle
DISTINCT in a more efficient way:
Probably (although the interactions with ORDER BY might be tricky).
No one has touched that part of the planner in a very
Neil Conway [EMAIL PROTECTED] writes:
On Mon, 2005-19-09 at 16:27 +0200, Hans-Jürgen Schönig wrote:
I was wondering whether it is possible to teach the planner to handle
DISTINCT in a more efficient way:
[...]
Isn't it possible to perform the same operation using a
HashAggregate?
Greg Stark [EMAIL PROTECTED] writes:
DISTINCT is really just special a case of GROUP BY. Even DISTINCT ON is just
GROUP BY with a kind of first() aggregate function. What would be really
neat would be to teach GROUP BY about first() and last() and how it can skip
over some index entries and
Tom Lane [EMAIL PROTECTED] writes:
I do think hash aggregation is a plausible alternative implementation of
plain DISTINCT, but I don't see the case for using it for DISTINCT ON.
It could be done without presorting the input though not with a simple
first()-like function. It would have be a
Added to TODO:
* Allow DISTINCT to use hashing like GROUP BY
---
Greg Stark wrote:
Neil Conway [EMAIL PROTECTED] writes:
On Mon, 2005-19-09 at 16:27 +0200, Hans-J?rgen Sch?nig wrote:
I was wondering
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