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Purpose:
    To more carefully describe the
        -- behavior of H5Pset_external
        -- appropriate usage of H5Pset_shuffle

Description:
    H5Pset_external
      Add notes that first H5Pset_external call sets the dataset as EXTERNAL
      and identifies the first file in the series of external files that
      will hold the dataset; subsequent calls identify additional files;
      all external files must be declared before the dataset is created;
      and the library will create files that don't yet exist on the system
      at the time that H5Dwrite is called to write data to that file.
    H5Pset_shuffle
      Added notes regarding usage of H5Pset_shuffle in concert with a
      compression filter.
    And, as always, a few copy edits.
This commit is contained in:
Frank Baker 2004-07-02 17:27:00 -05:00
parent 145fc6d7e7
commit 0f7e776650
1 changed files with 33 additions and 14 deletions
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doc/html/RM_H5P.html
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@ -2328,7 +2328,6 @@ END SUBROUTINE h5pget_class_parent_f
include the following:
<pre>
H5FD_CORE
H5FD_DPSS
H5FD_FAMILY
H5FD_GASS
H5FD_LOG
@ -6428,35 +6427,49 @@ END SUBROUTINE h5pset_edc_check_f
<dt><strong>Purpose:</strong>
<dd>Adds an external file to the list of external files.
<dt><strong>Description:</strong>
<dd><code>H5Pset_external</code> adds an external file to the
list of external files.
<dd>The first call to <code>H5Pset_external</code> sets the
<i>external storage</i> property in the property list,
thus designating that the dataset will be stored in
one or more non-HDF5 file(s) external to the HDF5 file.
This call also adds the file <code>name</code> as the
first file in the list of external files.
Subsequent calls to the function add the named file as
the next file in the list.
<p>
If a dataset is split across multiple files then the files
If a dataset is split across multiple files, then the files
should be defined in order. The total size of the dataset is
the sum of the <code>size</code> arguments for all the external files. If
the total size is larger than the size of a dataset then the
dataset can be extended (provided the data space also allows
the extending).
<p>
The <code>size</code> argument specifies number of bytes reserved
The <code>size</code> argument specifies the number of bytes reserved
for data in the external file.
If <code>size</code> is set to <code>H5F_UNLIMITED</code>, the
external file can be of unlimited size and no more files can be added to
the external files list.
external file can be of unlimited size and no more files can be added
to the external files list.
<p>
All of the external files for a given dataset must be
specified with <code>H5Pset_external</code>
<i>before</i> <code>H5Dcreate</code> is called to create
the dataset.
If one these files does not exist on the system when
<code>H5Dwrite</code> is called to write data to it,
the library will create the file.
<dt><strong>Parameters:</strong>
<ul><table>
<tr>
<td valign="top"><em>hid_t</em> <code>plist</code></td>
<td valign="top"><em>hid_t</em> <code>plist</code></td>
<td valign="top">IN: Identifier of a dataset creation property list.</td></tr>
<tr>
<td valign="top"><em>const&nbsp;char</em>&nbsp;<code>*name&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top"><em>const&nbsp;char</em>&nbsp;<code>*name&nbsp;&nbsp;&nbsp;&nbsp;</code></td>
<td valign="top">IN: Name of an external file.</td></tr>
<tr>
<td valign="top"><em>off_t</em> <code>offset</code></td>
<td valign="top"><em>off_t</em> <code>offset</code></td>
<td valign="top">IN: Offset, in bytes, from the beginning of the file
to the location in the file where the data starts.</td></tr>
<tr>
<td valign="top"><em>hsize_t</em> <code>size</code></td>
<td valign="top"><em>hsize_t</em> <code>size</code></td>
<td valign="top">IN: Number of bytes reserved in the file for the data.</td></tr>
</table></ul>
<dt><strong>Returns:</strong>
@ -8694,8 +8707,14 @@ END SUBROUTINE h5pset_preserve_f
closely related to each other and putting them together
can increase the compression ratio.
<p>
This filter is designed to be used in combination with
a compression filter.
As implied above, the primary value of the shuffle filter
lies in its coordinated use with a compression filter;
it does not provide data compression when used alone.
When the shuffle filter is applied to a dataset
immediately prior to the use of a compression filter,
the compression ratio achieved is often superior to that
achieved by the use of a compression filter without
the shuffle filter.
<dt><strong>Parameters:</strong>
<ul><table>
<tr>
@ -9683,7 +9702,7 @@ And in this document, the
Describes HDF5 Release 1.7, the unreleased development branch; working toward HDF5 Release 1.8.0
</address><!-- #EndLibraryItem --><SCRIPT LANGUAGE="JAVASCRIPT">
<!--
document.writeln("Last modified: 10 March 2004");
document.writeln("Last modified: 2 July 2004");
-->
</SCRIPT>