Changes between Version 189 and Version 190 of WKTRaster/SpecificationWorking03
- 11/29/11 14:54:57 (18 months ago)
v189 v190 537 537 PostGIS is using the typmod feature of PostgreSQL to 'store' metadata about a table and then display them in the geometry_column view. Unfortunately the typmod is limited to XXX bytes and there is too much information to 'store' about a raster table to use typmod. PostGIS raster will therefore use another approach consisting in 'storing' metadata about a raster table as constraint on the table. A set of constraint will be applied to a raster table and those constraint will be read and displayed by the raster_column view. 538 538 539 The major changes concerning the raster_column tableare as follow: 539 The are as follow: 540 540 541 541 * There will be a flexible !ApplyRasterConstraint() function trying to apply a set of constraint on a table. As for any constraint, each constraint will be successfully applied only when all the rows of the table fulfil this constraint. The list of potential constraint applied by the C loader (using the !ApplyRasterConstraint function) and hence the list of column available in the raster_column view will be: srid int, alignment (align on a upperleft x and y), scalex float8, scaley float8, width int, height int, numberofband int, pixeltypes text, nodatavalues float in addition to the 'r_table_catalog', 'r_table_schema', 'r_table_name' and 'r_column' columns. There is still discussion about if global extent as a geometry should be added to this list. Comments are welcomes. … … 545 545 * The raster_column view will derive columns of metadata from the constraints applied to each table listed. When a constraint does not exist (because it could not be applied successfully to the table by !ApplyRasterconstraint()), the column corresponding to this constraint for this table will be null. 546 546 547 The major changes concerning the raster_overview tableare as follow: 547 The are as follow: 548 548 549 549 * The raster_overview table will also be replaced with a raster_overview view. … … 553 553 * The raster_overview table will NOT be created by default by the rtpostgis.sql script. It will be the responsibility of applications to use the !ApplyOverviewConstraints and ST_CreateOverview() function to enable overviews support. 554 554 555 The major changes concerning the raster2pgsql loaderare as follow: 555 are as follow: 556 556 557 557 * We are working on a new C importer to get rid of any Python, Numpy and Python GDAL binding dependency.