[GRASS-dev] [GRASS GIS] #2750: LZ4 when writing raster rows; better than double I/O bound r.mapcalc speed

[GRASS GIS]

#2750: LZ4 when writing raster rows; better than double I/O bound r.mapcalc speed
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  Reporter:  sprice       |      Owner:  grass-dev@…
      Type:  enhancement  |     Status:  new
  Priority:  normal       |  Milestone:  7.1.0
 Component:  Raster       |    Version:  svn-trunk
Resolution:               |   Keywords:  ZLIB LZ4 ZSTD
       CPU:  OSX/Intel    |   Platform:  MacOSX
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Comment (by wenzeslaus):

 Replying to [comment:11 sprice]:
 > Completely random data is not a good test because (in theory) it won't
 compress. However, it looks like it demonstrated the expected results.

 Yes, probably G7:r.surf.fractal or G7:r.random.surface are better, but
 G7:r.mapcalc with `rand()` is kind of worst-case scenario and the
 compression still worked well!

 > If you do a diff with n_les_assemble.c...

 I've created a separate ticket #2754 for this. Let's discuss it there.

 I've executed the tests with `GRASS_COMPRESS_NULLS=1` in combination with
 default compression and `GRASS_INT_LZ4=1` and they seems to be OK
 (although there is some issue with ''r.slope.aspect'' test but that's
 unrelated). But still, the test coverage is limited, user testing is
 needed.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2750#comment:12>
GRASS GIS <https://grass.osgeo.org>