Changes between Version 23 and Version 24 of WKTRaster/GDALDriverSpecificationWorking

Timestamp:

Feb 17, 2011, 3:18:34 PM (13 years ago)

Author:

pracine

Comment:

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WKTRaster/GDALDriverSpecificationWorking

@@ -103 +103 @@
   * Each !ReadBlock call forces a new server round, constructing a Box and getting the raster row that contains it. This can be really slow, in case of huge raster coverages (question raised in ticket #497 too). 
 
+ '''Pierre question:''' Why does each IReadBlock force a new server round and IRasterIO not?
+
 '''Open question''': How to get the needed metadata in case of ONE_RASTER_PER_TABLE arrangement. As argued in ticket #497, executing ''ST_Extent'' or ''ST_Metadata'' without limits over a big table can be a really heavy process.
+
+ '''Pierre question:''' How long take a ST_Extent query on a 1 000 000 tiles indexed table?
 
 '''Open question''': What should be the general r/w algorithm? 
 jorgearevalo: I think the strategy ''read as much data as you can'' should be the right one, to minimize server rounds. This is: construct a query that, using ''ST_Intersects'', fetches as much rows as possible. This query would be executed in ''IRasterIO'' method. But I don't know how to choose the geographic limits for the query (how much data is ''as much data as you can''?)
 
+ '''Pierre question:''' What do you mean by "I don't know how to choose the geographic limits"? Can't you deduce them from the parameter passed to the function and the metadata of the rasters?
+
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