The XArray implementation that uses Zarr for storage
provides a mechanism to simulate named dimensions.
It does this by adding a per-variable attribute called
_ARRAY_DIMENSIONS. This attribute contains a list of names
to be matched against the shape values of the variable.
In effect a named dimension is created with the name
_ARRAY_DIMENSIONS(i) and length shape(i) for all i
in range 0..rank(variable).
Both read and write support is provided.
This XArray support is only invoked if the mode value
of "xarray" is defined. So for example, as in this URL.
````
https://s3.us-west-1.amazonaws.com/bucket/dataset#mode=nczarr,xarray,s3
````
Note that the "xarray" mode flag also implies mode flag "zarr", so the above
is equivalent to this URL.
````
https://s3.us-west-1.amazonaws.com/bucket/dataset#mode=nczarr,zarr,xarray,s3
````
The primary change to implement this was to unify the handling
of dimension references in libnczarr/zsync.
A test for this and other pure-zarr features was added as
nczarr_test/run_purezarr.sh
Other changes:
* Make sure distcheck leaves no files around.
* Change the special attribute flag DIMSCALEFLAG to HIDDENATTRFLAG
to support the xarray attribute.
* Annotate the zmap implementations with feature flags such as
WRITEONCE (for zip files).
re: Issue
The netcdf dispatch table version was defined in several places.
Modify to only require defining it in CMakeLists.txt and configure.ac.
Fix entailed the following changes:
* Up the NC_DISPATCH_VERSION from 2 to 3 in configure.ac and CMakeLists.txt
* Create include/netcdf_dispatch.h.in and use it to configure include/netcdf_dispatch.h
* For CMAKE, make it search CMAKE_CURRENT_BINARY_DIR so code can locate the configured netcdf_dispatch.h
* Add entry to config.h.cmake.in for NC_DISPATCH_VERSION
* Move NCerror from include/ncdispatch.h to libdap2/nccomon.h
* Fix an API problem re nchttp.h
* Fix a conversion warning in libdispatch/dinfermodel.c
re: Issue https://github.com/Unidata/netcdf-c/issues/1936
The algorithm controlling interaction of -d 0 -F and -c / options
is incorrect.
The fix:
1. make -d 0 => no deflation
2. make -F properly use the filter specs to decide.
Also added a test case to ncdump/tst_nccopy4.sh.
The primary change is to support the use of a zip file as a
storage format. Simultaneously the .nz4 support is made obsolete
Use of zip requires the libzip support library, so a number of
changes to the build files (Makefile.am, CMakeLists.txt) are
necessary to locate and incorporate libzip. The nczarr_tests
tests are also changed to add zip testing.
Other changes:
* Make sure distcheck leaves no files around.
* Add some functions to netcdf_aux to export some functions of libnetcdf.
* Add a new error NC_EFOUND as the complement of NC_EEMPTY.
* Add tracing support to nclog and use it in libnczarr.
* Modify the zmap interface to support the writeonce semantics of zip.
* Create a new s3util.c to support a variety of S3 auxilliary functions.
* EXTERNL'ize a number of functions so they can be used in s3util.
* Add support for the S3 ListObjects CommonPrefixes mechanism
to improve search.
* Add experimental support for running nczarr X s3 tests against
the actual Amazon S3 cloud.
Changes:
1. add "use_nczarr: [ nczarr_off, nczarr_on ]" to matrix
2. add libzip-dev to the apt installs (might need caching).
3. convert deprecated "--enable-netcdf-4" to "--enable-hdf5" (also for cmake)
re: esupport 31942
* Add a new set of remote tests based on using the opendap hyrax server
* Re-enable --enable-dap-remote-tests as default on
* Make it possible to query the DMR separate from the DAP
so that it is possible to delay reading data until it is actually
requested. This make things like ncdump -h much more efficient.
* Fix handling of <Map>s in DMRs.
* Fix some memory leaks
than HDF5 1.8. This will allow for HDF5 features (VDS, SWMR, new references, etc...)
which may require to have a superblock greater than v2.
See for discussion Ref: Update HDF5 format compatibility Unidata#951
