# snmpa_local_db

### MODULE

snmpa_local_db

### MODULE SUMMARY

The SNMP built-in database

### DESCRIPTION

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.

- Insertions and deletions are inefficient for large tables.

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.

### Common Data Types

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.

### EXPORTS

`dump() -> ok | {error, Reason}`

Types:

`Reason = term()`

This function can be used to manually dump the database to file.

`match(NameDb, Pattern)`

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.

### See Also

ets(3), dets(3), snmp_generic(3)

### AUTHORS

Martin Björklund - support@erlang.ericsson.se
Klas Eriksson - support@erlang.ericsson.se

snmp 4.8.4
Copyright © 1991-2007 Ericsson AB