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< th colspan = "3" align = "center" > DB_ENV-> add_data_dir()< / th >
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The DB_ENV Handle
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< h2 class = "title" style = "clear: both" > < a id = "envadd_data_dir" > < / a > DB_ENV-> add_data_dir()< / h2 >
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< pre class = "programlisting" > #include < db.h>
int
DB_ENV-> add_data_dir(DB_ENV *dbenv, const char *dir); < / pre >
< p >
Add the path of a directory to be used as the location of the access
method database files. Paths specified to the
< a class = "xref" href = "dbopen.html" title = "DB->open()" > DB-> open()< / a > function will be
searched relative to this path. Paths set using this method are
additive, and specifying more than one will result in each specified
directory being searched for database files.
< / p >
< p >
If no database directories are specified, database files must be named
either by absolute paths or relative to the environment home
directory. See
< a href = "../../programmer_reference/env_naming.html" class = "olink" > Berkeley DB File Naming< / a >
for more information.
< / p >
< p >
The database environment's data directories may also be configured
using the environment's < a href = "../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class = "olink" > DB_CONFIG< / a > file. The syntax of the entry
in that file is a single line with the string "add_data_dir", one
or more whitespace characters, and the directory name.
Note that if you use this method for your application, and you also want to use the
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< a class = "xref" href = "db_recover.html" title = "db_recover" > db_recover< / a > or
< a class = "xref" href = "db_archive.html" title = "db_archive" > db_archive< / a >
utilities, then you should create a < a href = "../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class = "olink" > DB_CONFIG< / a > file and set
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the "add_data_dir" parameter in it.
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< p >
The < code class = "methodname" > DB_ENV-> add_data_dir()< / code > method configures operations performed
using the specified < a class = "link" href = "env.html" title = "Chapter > DB_ENV< / a >
handle, not all operations performed on the underlying database environment.
< / p >
< p >
The < code class = "methodname" > DB_ENV-> add_data_dir()< / code > method may not be called after the
< a class = "xref" href = "envopen.html" title = "DB_ENV->open()" > DB_ENV-> open()< / a > method is called.
If the database environment already exists when
< a class = "xref" href = "envopen.html" title = "DB_ENV->open()" > DB_ENV-> open()< / a > is called, the
information specified to < code class = "methodname" > DB_ENV-> add_data_dir()< / code > must be consistent
with the existing environment or corruption can occur.
< / p >
< p >
The < code class = "methodname" > DB_ENV-> add_data_dir()< / code > < span >
< span >
method returns a non-zero error value on failure and 0 on success.
< / span >
< / span >
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< h3 class = "title" > < a id = "id3703472" > < / a > Parameters< / h3 >
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< h4 class = "title" > < a id = "id3703461" > < / a > dir< / h4 >
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The < span class = "bold" > < strong > dir< / strong > < / span > parameter is a directory to
be used as a location for database files.
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When using a Unicode build on Windows (the default), this argument will be interpreted
as a UTF-8 string, which is equivalent to ASCII for Latin characters.
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< h3 class = "title" > < a id = "id3703543" > < / a > Errors< / h3 >
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< p >
The < code class = "methodname" > DB_ENV-> add_data_dir()< / code > < span >
< span >
method may fail and return one of the following non-zero errors:
< / span >
< / span >
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< div class = "sect3" lang = "en" xml:lang = "en" >
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< h4 class = "title" > < a id = "id3703705" > < / a > EINVAL< / h4 >
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If the method was called after < a class = "xref" href = "envopen.html" title = "DB_ENV->open()" > DB_ENV-> open()< / a >
was called; or if an invalid flag value or parameter was specified.
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< a class = "link" href = "env.html" title = "Chapter > DB_ENV< / a >
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< h3 class = "title" > < a id = "id3700245" > < / a > See Also< / h3 >
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< a class = "xref" href = "env.html#envlist" title = "Database Environments and Related Methods" > Database Environments and Related Methods< / a >
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