Sindbad~EG File Manager
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<p>Library Version 18.1.40</p>
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environment</th>
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<h2 class="title" style="clear: both"><a id="env_open"></a>Opening databases within the
environment</h2>
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<p>
Once the environment has been created, database handles may
be created and then opened within the environment. This is
done by calling the <a href="../api_reference/C/dbcreate.html" class="olink">db_create()</a> function and specifying the
appropriate environment as an argument.
</p>
<p>
File naming, database operations, and error handling will
all be done as specified for the environment. For example, if
the <a href="../api_reference/C/envopen.html#envopen_DB_INIT_LOCK" class="olink">DB_INIT_LOCK</a> or <a href="../api_reference/C/envopen.html#envopen_DB_INIT_CDB" class="olink">DB_INIT_CDB</a> flags were specified when
the environment was created or joined, database operations
will automatically perform all necessary locking operations
for the application.
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<p>
The following is a simple example of opening two databases
within a database environment:
</p>
<a id="prog_env28"></a>
<pre class="programlisting">DB_ENV *dbenv;
DB *dbp1, *dbp2;
int ret;
dbenv = NULL;
dbp1 = dbp2 = NULL;
/*
* Create an environment and initialize it for additional error
* reporting.
*/
if ((ret = db_env_create(&dbenv, 0)) != 0) {
fprintf(errfp, "%s: %s\n", progname, db_strerror(ret));
return (ret);
}
dbenv->set_errfile(dbenv, errfp);
dbenv->set_errpfx(dbenv, progname);
/* Open an environment with just a memory pool. */
if ((ret =
dbenv->open(dbenv, home, DB_CREATE | DB_INIT_MPOOL, 0)) != 0) {
dbenv->err(dbenv, ret, "environment open: %s", home);
goto err;
}
/* Open database #1. */
if ((ret = db_create(&dbp1, dbenv, 0)) != 0) {
dbenv->err(dbenv, ret, "database create");
goto err;
}
if ((ret = dbp1->open(dbp1,
NULL, DATABASE1, NULL, DB_BTREE, DB_CREATE, 0664)) != 0) {
dbenv->err(dbenv, ret, "DB->open: %s", DATABASE1);
goto err;
}
/* Open database #2. */
if ((ret = db_create(&dbp2, dbenv, 0)) != 0) {
dbenv->err(dbenv, ret, "database create");
goto err;
}
if ((ret = dbp2->open(dbp2,
NULL, DATABASE2, NULL, DB_HASH, DB_CREATE, 0664)) != 0) {
dbenv->err(dbenv, ret, "DB->open: %s", DATABASE2);
goto err;
}
return (0);
err: if (dbp2 != NULL)
(void)dbp2->close(dbp2, 0);
if (dbp1 != NULL)
(void)dbp1->close(dbp1, 0);
(void)dbenv->close(dbenv, 0);
return (1);
}</pre>
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