[postgis-users] ST_Quantile

[Bborie Park]

Joan,

I confirm that there is a segfault.  Can you add a ticket for this? 
I'll take a look ASAP.

-bborie

On 01/27/2012 11:19 AM, Joan wrote:
> Hi Steve,
>
> I have gotten the same problem (db server stopped running).
>
> Joan
>
> On 27 January 2012 20:05, Stephen Woodbridge<woodbri at swoodbridge.com>wrote:
>
>> Joan,
>>
>> I've never used these function, but try doing:
>>
>> select st_quantile('kbd_ext', 'rast', 0.75);
>>
>> Since you probably do not want this called once for every row in the table.
>>
>> -Steve
>>
>>
>> On 1/27/2012 2:03 PM, Joan wrote:
>>
>>> Hi Bborie,
>>>
>>> This is my query and it crashes the db server.
>>> select st_quantile('kbd_ext', 'rast', 0.75) from kbd_ext limit 10;
>>>
>>> Joan
>>>
>>> On 27 January 2012 19:14, Bborie Park<bkpark at ucdavis.edu
>>> <mailto:bkpark at ucdavis.edu>>  wrote:
>>>
>>>     Hey Joan,
>>>
>>>     Assuming your whole coverage is in a table, you should use the
>>>     table/column version of ST_Quantile (which by the looks of it is
>>>     undocumented for some reason).
>>>
>>>     The function definition of ST_Quantile(rastertable, rastercolumn) is...
>>>
>>>     st_quantile(rastertable text, rastercolumn text, nband int DEFAULT
>>>     1, exclude_nodata_value boolean DEFAULT TRUE, quantiles double
>>>     precision[] DEFAULT NULL)
>>>
>>>     At the moment an aggregate version of ST_Quantile (and the other
>>>     basic stats functions) does not exist.  It is expected that one will
>>>     be written for PostGIS 2.1 assuming dev-time is available.
>>>
>>>     -bborie
>>>
>>>
>>>     On 01/27/2012 09:06 AM, Joan wrote:
>>>
>>>         Hi,
>>>
>>>         I would like to find the quantile values of a whole raster
>>>         coverage, but
>>>         ST_Quantile returns quantile values of each tile. Which would be
>>>         the best
>>>         method to approximate the quantile value of the whole coverage?
>>>
>>>         Regards,
>>>
>>>         Joan
>>>
>>>
>>>
>>>
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>>>
>>>
>>>     --
>>>     Bborie Park
>>>     Programmer
>>>     Center for Vectorborne Diseases
>>>     UC Davis
>>>     530-752-8380
>>>     bkpark at ucdavis.edu<mailto:bkpark at ucdavis.edu>
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-- 
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark at ucdavis.edu