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<header>
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</copyright>
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<title>snmpa_local_db</title>
<prepared></prepared>
<responsible></responsible>
<docno></docno>
<approved></approved>
<checked></checked>
<date></date>
<rev></rev>
<file>snmpa_local_db.xml</file>
</header>
<module>snmpa_local_db</module>
<modulesummary>The SNMP built-in database</modulesummary>
<description>
<p>The module <c>snmpa_local_db</c> contains functions for
implementing tables (and variables) using the SNMP built-in
database. The database exists in two instances, one volatile
and one persistent. The volatile database is implemented with
ets. The persistent database is implemented with dets.
</p>
<p>There is a scaling problem with this database.
</p>
<list type="bulleted">
<item>Insertions and deletions are inefficient for large tables.
</item>
</list>
<p>This problem is best solved by using Mnesia instead.
</p>
<p>The following functions describe the interface to
<c>snmpa_local_db</c>. Each function has a Mnesia equivalent.
The argument <c>NameDb</c> is a tuple <c>{Name, Db}</c> where
<c>Name</c> is the symbolic name of the managed object (as defined
in the MIB), and <c>Db</c> is either <c>volatile</c> or
<c>persistent</c>. <c>mnesia</c> is not possible since all these
functions are <c>snmpa_local_db</c> specific.
</p>
</description>
<section>
<title>Common Data Types</title>
<p>In the functions defined below, the following types are
used:
</p>
<list type="bulleted">
<item>
<p><c>NameDb = {Name, Db}</c></p>
</item>
<item>
<p><c>Name = atom(), Db = volatile | persistent</c></p>
</item>
<item>
<p><c>RowIndex = [int()]</c></p>
</item>
<item>
<p><c>Cols = [Col] | [{Col, Value}], Col = int(), Value = term()</c></p>
</item>
</list>
<p>where <c>RowIndex</c> denotes the last part of the OID, that
specifies the index of the row in the table. <c>Cols</c> is a
list of column numbers in case of a get operation, and a list of
column numbers and values in case of a set operation.
</p>
</section>
<funcs>
<func>
<name>dump() -> ok | {error, Reason}</name>
<fsummary>Dump the database to disk</fsummary>
<type>
<v>Reason = term()</v>
</type>
<desc>
<p>This function can be used to manually dump the database
to file.</p>
</desc>
</func>
<func>
<name>match(NameDb, Pattern)</name>
<fsummary>Perform a match on the table</fsummary>
<desc>
<p>Performs an ets/dets matching on the table.
See Stdlib documentation, module ets, for a description of
<c>Pattern</c> and the return values.</p>
</desc>
</func>
<func>
<name>print()</name>
<name>print(TableName)</name>
<name>print(TableName, Db)</name>
<fsummary>Print the database to screen</fsummary>
<type>
<v>TableName = atom()</v>
</type>
<desc>
<p>Prints the contents of the database on
screen. This is useful for debugging since the
<c>STANDARD-MIB</c> and <c>OTP-SNMPEA-MIB</c>
(and maybe your own MIBs) are stored in <c>snmpa_local_db</c>.
</p>
<p><c>TableName</c> is an atom for a table in the database.
When no name is supplied, the whole database is shown.</p>
</desc>
</func>
<func>
<name>table_create(NameDb) -> bool()</name>
<fsummary>Create a table</fsummary>
<desc>
<p>Creates a table. If the table already exist, the old copy
is destroyed.
</p>
<p>Returns <c>false</c> if the <c>NameDb</c> argument is
incorrectly specified, <c>true</c> otherwise.</p>
</desc>
</func>
<func>
<name>table_create_row(NameDb, RowIndex, Row) -> bool()</name>
<fsummary>Create a row in a table</fsummary>
<type>
<v>Row = {Val1, Val2, ..., ValN}</v>
<v>Val1 = Val2 = ... = ValN = term()</v>
</type>
<desc>
<p>Creates a row in a table. <c>Row</c> is a tuple with
values for all columns, including the index columns.</p>
</desc>
</func>
<func>
<name>table_delete(NameDb) -> void()</name>
<fsummary>Delete a table</fsummary>
<desc>
<p>Deletes a table.</p>
</desc>
</func>
<func>
<name>table_delete_row(NameDb, RowIndex) -> bool()</name>
<fsummary>Delete the row in the table</fsummary>
<desc>
<p>Deletes the row in the table.</p>
</desc>
</func>
<func>
<name>table_exists(NameDb) -> bool()</name>
<fsummary>Check if a table exists</fsummary>
<desc>
<p>Checks if a table exists.</p>
</desc>
</func>
<func>
<name>table_get_row(NameDb, RowIndex) -> Row | undefined</name>
<fsummary>Get a row from the table</fsummary>
<type>
<v>Row = {Val1, Val2, ..., ValN}</v>
<v>Val1 = Val2 = ... = ValN = term()</v>
</type>
<desc>
<p><c>Row</c> is a tuple with values for all columns,
including the index columns.</p>
</desc>
</func>
</funcs>
<section>
<title>See Also</title>
<p>ets(3), dets(3), snmp_generic(3)
</p>
</section>
</erlref>
