Hi Resmi-C, We have a new cover each 16-day from Landsat 8. But I only want one cover in result of my query. I had add new column 'date_of_data' to store date of a raster. And I think range could solve my problem. Thank you!
On Wed, Mar 19, 2014 at 4:16 PM, Rémi Cura <[email protected]> wrote: > It is a little bit hard to understand what you mean.. > As a summary : > _you have lot's of rasters. > _Each one as a position (and a date associated?). > > You need to get a raster based on its position (where st_intersects(..))), > but it is not sufficient and you would like too also filter by date. > > You can do so easily by adding a condition in the WHERE, like > AND my_date < .... AND my_date > ... > (or using time_range > http://www.postgresql.org/docs/9.2/static/rangetypes.html , if postgres > version >= 9.2) > > Now about making a table per day, it is entirely another question. > logically wise, you could get the strict equivalent by adding a column on > your raster table with the day of acquisition (the real date would be > better). > > Now deciding to split or not your big raster table into several smaller is > more about performance, and should be carefully designed ( > http://www.postgresql.org/docs/9.3/static/ddl-partitioning.html), based > on row number, index size, your memory size, how the table will grow, what > kind of usage you make of it, and so on. > > > Cheers, > Rémi-C > > > > 2014-03-19 8:28 GMT+01:00 Jackie Nguyen <[email protected]>: > >> Hi PostGIS Users, >> >> I have a huge dataset of raster in PostGIS. Each scene is divided into >> tiles (tile-size 500x500). I was trying to SELECT rast FROM landsat8 >> WHERE ST_Intersects(rast, polygon). It runs very slow, because it >> returns longitudinal scenes of raster. Where I just want one day's scene. >> But the problem is if I query with fixed date, adjacent scene with >> different date won't be selected. That's not true. >> So I think about some solutions: >> >> - Because Landsat 8 re-visiting every 16 days, so I will insert every >> 16 days into different table. So I can query from raster that cover all >> the >> earth without duplicate. >> - I'm not sure about ST_Within(), ST_DWithin() then SELECT rast that >> doesn't overlap other >50% >> >> What would you do in this situation? >> >> -- >> ---- >> Jackie >> >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >> > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > -- ---- Jackie
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