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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>

