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The module snmpa_local_db 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.
There is a scaling problem with this database.
This problem is best solved by using Mnesia instead.
The following functions describe the interface to
snmpa_local_db. Each function has a Mnesia equivalent.
The argument NameDb is a tuple {Name, Db} where
Name is the symbolic name of the managed object (as defined
in the MIB), and Db is either volatile or
persistent. mnesia is not possible since all these
functions are snmpa_local_db specific.
In the functions defined below, the following types are used:
NameDb = {Name, Db}
Name = atom(), Db = volatile | persistent
RowIndex = [int()]
Cols = [Col] | [{Col, Value}], Col = int(), Value =
term()
where RowIndex denotes the last part of the OID, that
specifies the index of the row in tha table. Cols 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.
dump() -> ok | {error, Reason}
Types:
Reason = term()
This function can be used to manually dump the database to file.
Performs an ets/dets matching on the table.
See Stdlib documentation, module ets, for a description of
Pattern and the return values.
print()
print(TableName)
print(TableName, Db)
Types:
TableName = atom()
Prints the contents of the database on
screen. This is useful for debugging since the
STANDARD-MIB and OTP-SNMPEA-MIB
(and maybe your own MIBs) are stored in snmpa_local_db.
TableName is an atom for a table in the database.
When no name is supplied, the whole database is shown.
table_create(NameDb) -> bool()
Creates a table. If the table already exist, the old copy is destroyed.
Returns false if the NameDb argument is
incorrectly specified, true otherwise.
table_create_row(NameDb, RowIndex, Row) -> bool()
Types:
Row = {Val1, Val2, ..., ValN}
Val1 = Val2 = ... = ValN = term()
Creates a row in a table. Row is a tuple with
values for all columns, including the index columns.
table_delete(NameDb) -> void()
Deletes a table.
table_delete_row(NameDb, RowIndex) -> bool()
Deletes the row in the table.
table_exists(NameDb) -> bool()
Checks if a table exists.
table_get_row(NameDb, RowIndex) -> Row | undefined
Types:
Row = {Val1, Val2, ..., ValN}
Val1 = Val2 = ... = ValN = term()
Row is a tuple with values for all columns,
including the index columns.
ets(3), dets(3), snmp_generic(3)