[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 mmetz):

 Replying to [comment:49 neteler]:
 > Replying to [comment:48 mmetz]:
 > > In your opinion:
 > > * Adding new compression methods in G71 for cell/fcell files that are
 not readable by G70 is ok.
 >
 > No. If the format is broken, we need to call it G8 and provide
 converters.

 If we call it G8, converters are not needed because trunk as it is now can
 read G7 and G6 rasters.

 Assuming trunk should be released as G7.1:

 For full compatibility of relbr70 with trunk, not only read support for
 compressed null files would need to be backported, but also and more
 importantly read support for compressed cell/fcell files. These are new
 features at library level involving quite a few changes.

 The current default settings in trunk are compatible with relbr70, and I
 do not see a reason to change the respective default settings in trunk.
 What exactly is the reason why null file compression should be enabled by
 default in trunk?

 I will not backport the changes I did to trunk with regard to cell/cell
 file and null file compression because these are new features which should
 IMHO not go into an existing release branch. Someone else would need to do
 the backporting.

 IMHO, the new compression methods for cell/fcell files are more important
 than null file compression because the potential gains in disk space and
 processing speed are much higher. Recompressing a large cell file from
 ZLIB to BZIP2 can gain disk space several times larger than the
 corresponding uncompressed(!) null file. In relation, a compressed null
 file would only be a small added bonus but not a substantial gain in free
 disk space. On the other hand, compressing cell/fcell files with LZ4 can
 substantially speed up processing time.

 Short answer: release trunk now as G8, no need for converters because
 backward compatibility exists.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2750#comment:50>
GRASS GIS <https://grass.osgeo.org>