@postgresql.org
Subject: Re: [PERFORM] Cursor + upsert (astronomical data)
I am not sure I understand the problem fully, e.g. what to do if there are
observations A,B and C with A to B and B to C less then treshold and A to C
over treshold, but anyway.
Could you first apply a kind of grid to your
@postgresql.org; Sergey Karpov
Subject: Re: [PERFORM] Cursor + upsert (astronomical data)
Jiri,
as I understand your problem is called crossmatch ? I attach pdf of our work
in progress, where we compared several spatial indexing techniques, including
postgis, q3c and new pgsphere. Sergey Karpov
Hi Jiri,
I’m really interested in those [clustering] algorithms and study them. But
I would need somebody to point me directly at a specific algorithm to look
at. The main problem with choosing the right one (which couldn’t get over
even my university teacher) is that you don’t know the number
-performance@postgresql.org
Subject: Re: [PERFORM] Cursor + upsert (astronomical data)
Hi Jiri,
I understand your problem (and I actually have exactly the same in my sky
monitoring experiment). Unfortunately, I have no complete solution for it as of
now.
I just may suggest you to look at q3c_ipixcenter
On Sat, Jul 26, 2014 at 3:46 AM, Jiří Nádvorník nadvornik...@gmail.com
wrote:
The reason why I solve the performance issues here is that the table of
observations has atm cca 3e8 rows after 1.5 year of gathering the data. The
number growth is linear.
So about 500,000 new records a day.
I am not sure I understand the problem fully, e.g. what to do if there are
observations A,B and C with A to B and B to C less then treshold and A to C
over treshold, but anyway.
Could you first apply a kind of grid to your observations? What I mean is
to round your coords to, say, 1/2 arcsec on
To: Jiří Nádvorník
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Cursor + upsert (astronomical data)
I am not sure I understand the problem fully, e.g. what to do if there are
observations A,B and C with A to B and B to C less then treshold and A to C
over treshold, but anyway.
Could
] *On Behalf Of *Vitalii
Tymchyshyn
*Sent:* Sunday, July 27, 2014 8:06 AM
*To:* Jiří Nádvorník
*Cc:* pgsql-performance@postgresql.org
*Subject:* Re: [PERFORM] Cursor + upsert (astronomical data)
I am not sure I understand the problem fully, e.g. what to do if there are
observations A,B
[Craig]
If you haven't looked at clustering algorithms yet, you might want to do so.
Your problem is a special case of clustering, where you have a large number
of small clusters. A good place to start is the overview on Wikipedia:
http://en.wikipedia.org/wiki/Cluster_analysis
According to this
...@gmail.com] *On Behalf Of *Vitalii
Tymchyshyn
*Sent:* Sunday, July 27, 2014 8:06 AM
*To:* Jiří Nádvorník
*Cc:* pgsql-performance@postgresql.org
*Subject:* Re: [PERFORM] Cursor + upsert (astronomical data)
I am not sure I understand the problem fully, e.g. what to do if there are
observations
Hello guys.
My issue kind of hits multiple topics, but the main question is about
performance. I think you need to understand the background a little bit to
be able to help me. So I will firstly define the problem and my solutions to
it and place the questions for you to the end of this
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