median and percentile function implementation
Hello
Three years ago we worked on implementation of median function.
/messages/by-id/AANLkTimRksUOgGsK7-gTXnvJJGL-1QvuqxidusZQwep6@mail.gmail.com
Can we implement this function now?
There are a few opened questions:
* immutable parameters of aggregate functions
* effective implementation when data are in memory
* effective implementation when data are out of memory
* effective implementation for usage as window function - running median.
Better than before, we can choose between hashing and sorting based
aggregation. But tuplesort implementation is not right for using as window
function. Second issue can be a not possible reusing of tuplesort for more
final functions - median, percentile in one query.
Ideas how to solve this task? Can we move forward in some points?
Regards
Pavel
On 08/26/2013 02:39 PM, Pavel Stehule wrote:
Hello
Three years ago we worked on implementation of median function.
/messages/by-id/AANLkTimRksUOgGsK7-gTXnvJJGL-1QvuqxidusZQwep6@mail.gmail.com
Can we implement this function now?
There are a few opened questions:
* immutable parameters of aggregate functions
* effective implementation when data are in memory
* effective implementation when data are out of memory
* effective implementation for usage as window function - running median.
Better than before, we can choose between hashing and sorting based
aggregation. But tuplesort implementation is not right for using as
window function. Second issue can be a not possible reusing of
tuplesort for more final functions - median, percentile in one query.Ideas how to solve this task? Can we move forward in some points?
Take a look at the standard-compliant WITHIN GROUP that is currently in
development for 9.4.
/messages/by-id/2b8b55b8ba82f83ef4e6070b95fb0cd0@news-out.riddles.org.uk
--
Vik
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
Hello
very nice! I tested it and works very well.
And I looking for implementation in core.
Two notes:
* should to support string_agg and array_agg
Regards
Pavel
2013/8/26 Vik Fearing <vik.fearing@dalibo.com>
Show quoted text
On 08/26/2013 02:39 PM, Pavel Stehule wrote:
Hello
Three years ago we worked on implementation of median function.
/messages/by-id/AANLkTimRksUOgGsK7-gTXnvJJGL-1QvuqxidusZQwep6@mail.gmail.com
Can we implement this function now?
There are a few opened questions:
* immutable parameters of aggregate functions
* effective implementation when data are in memory
* effective implementation when data are out of memory
* effective implementation for usage as window function - running median.
Better than before, we can choose between hashing and sorting based
aggregation. But tuplesort implementation is not right for using as
window function. Second issue can be a not possible reusing of
tuplesort for more final functions - median, percentile in one query.Ideas how to solve this task? Can we move forward in some points?
Take a look at the standard-compliant WITHIN GROUP that is currently in
development for 9.4./messages/by-id/2b8b55b8ba82f83ef4e6070b95fb0cd0@news-out.riddles.org.uk
--
Vik
On Mon, Aug 26, 2013 at 10:15 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
Hello
very nice! I tested it and works very well.
And I looking for implementation in core.
Two notes:
* should to support string_agg and array_agg
Regards
Pavel
2013/8/26 Vik Fearing <vik.fearing@dalibo.com>
On 08/26/2013 02:39 PM, Pavel Stehule wrote:
Hello
Three years ago we worked on implementation of median function.
/messages/by-id/AANLkTimRksUOgGsK7-gTXnvJJGL-1QvuqxidusZQwep6@mail.gmail.com
Can we implement this function now?
There are a few opened questions:
* immutable parameters of aggregate functions
* effective implementation when data are in memory
* effective implementation when data are out of memory
* effective implementation for usage as window function - running
median.Better than before, we can choose between hashing and sorting based
aggregation. But tuplesort implementation is not right for using as
window function. Second issue can be a not possible reusing of
tuplesort for more final functions - median, percentile in one query.Ideas how to solve this task? Can we move forward in some points?
Take a look at the standard-compliant WITHIN GROUP that is currently in
development for 9.4./messages/by-id/2b8b55b8ba82f83ef4e6070b95fb0cd0@news-out.riddles.org.uk
--
Vik
Thanks a ton!
We will definitely look at supporting at the two functions you mentioned.
Regards,
Atri
--
Regards,
Atri
l'apprenant
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers