2009/7/11 Frank Warmerdam <warmer...@pobox.com> > Jorge Arévalo wrote: > >> Hello, >> >> 2009/7/10 Tamas Szekeres <szeker...@gmail.com>: >> >>> Jorge, >>> >>> I'm a bit hesitant to think using a server cursor would be the best >>> approach >>> here. Could you explain why is this needed? >>> >> >> Yes. As now I'm working basically with regularly tiled coverages, an >> operation like SELECT rast FROM table gives me all the tiles. These >> tiles don't overlap, and its size can be the size of a block read for >> IReadBlock method. So, if I have a cursor, I can fetch the tile that >> the IRasterBlock needs as one of the rows of the resultset without >> having all the tiles loaded in memory at same time. >> > > Jorge, > > I'm not clear on how you know what row to take out of the resultset > for a given IReadBlock() call? How do you translate the x/y block > index into a resultset row offset? > > I would note that spatial searches *should* be quite fast if the > raster row is spatially indexed. >
Jorge, I'm thinking of exactly the same as Frank. It's ok you have the same block size in GDAL as the block size in the database but you might have to construct a different SQL query to select the corresponding block even if a single row is retrieved in a single IReadBlock call. Best regards, Tamas
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