With this function, you can get a support version of mnesia.

Activates a new checkpoint covering all Mnesia tables, including the schema, with maximum degree of redundancy, and performs a backup using backup_checkpoint/2 and backup_checkpoint/3. The default value of the backup callback module BackupMod is obtained by mnesia:system_info(backup_module).

Example

  MnesiaAssistant.BackupAndRestore.backup(backup_path)
  MnesiaAssistant.BackupAndRestore.backup(backup_path, module)

Read backup/1 document.

Read backup_checkpoint/3 document.

The :mnesia.backup_checkpoint/2 function is used in Mnesia to create a backup of the database at a specific checkpoint.

This function allows you to specify a checkpoint name, and Mnesia will generate a backup that includes all changes up to that point.

This is particularly useful for creating consistent backups of the database state at known good points, facilitating easier recovery in case of data corruption or loss.

The tables are backed up to external media using backup module BackupMod. Tables with the local contents property are backed up as they exist on the current node. BackupMod is the default backup callback module obtained by mnesia:system_info(backup_module). For information about the exact callback interface (the mnesia_backup behavior), see the User's Guide.

  backup_checkpoint(Name, Dest) -> result()
  backup_checkpoint(Name, Dest, Mod) -> result()

Example

  MnesiaAssistant.BackupAndRestore.backup_checkpoint(name, dest, mod)
  MnesiaAssistant.BackupAndRestore.backup_checkpoint(name, dest)

Performs a user-initiated dump of the local log file. This is usually not necessary, as Mnesia by default manages this automatically

Example:

  MnesiaAssistant.BackupAndRestore.dump_log() # --> :mnesia.dump_log()

Dumps a set of ram_copies tables to disc. The next time the system is started, these tables are initiated with the data found in the files that are the result of this dump. None of the tables can have disc-resident replicas.

Example:

  MnesiaAssistant.BackupAndRestore.dump_tables(tables) # --> :mnesia.dump_tables(tables)

The :mnesia.dump_to_textfile/1 function in Mnesia is used to dump the contents of one or more Mnesia tables to a text file. Each record is written to the file as an Erlang term, one term per line. This can be useful for backing up data or exporting it for analysis or use in other systems.

Dumps all local tables of a Mnesia system into a text file, which can be edited (by a normal text editor) and then be reloaded with mnesia:load_textfile/1. Only use this function for educational purposes. Use other functions to deal with real backups.

Example

  MnesiaAssistant.BackupAndRestore.dump_to_textfile("/path/to/person.txt")

Installs a backup as fallback. The fallback is used to restore the database at the next startup. Installation of fallbacks requires Erlang to be operational on all the involved nodes, but it does not matter if Mnesia is running or not. The installation of the fallback fails if the local node is not one of the disc-resident nodes in the backup.

Example:

  MnesiaAssistant.BackupAndRestore.install_fallback(source)
  # --> :mnesia.install_fallback(source)
  MnesiaAssistant.BackupAndRestore.install_fallback(source, module)
  # --> :mnesia.install_fallback(source, module)

Read install_fallback/1 document.

The :mnesia.load_textfile/1 function in Mnesia is used to load data from a text file into a Mnesia table. The text file should contain Erlang terms, with one term per line, matching the structure of the records in the target table.

Example

  MnesiaAssistant.BackupAndRestore.load_textfile("/path/to/person.txt")

With this function, tables can be restored online from a backup without restarting Mnesia. Opaque is forwarded to the backup module. args is a list of the following tuples:

• Op: skip_tables | clear_tables | keep_tables | restore_tables

• Arg: {module, module()} | {Op, [table()]} | {default_op, Op}

1. {module,BackupMod}. The backup module BackupMod is used to access the backup media. If omitted, the default backup module is used.
2. {skip_tables, TabList}, where TabList is a list of tables that is not to be read from the backup.
3. {clear_tables, TabList}, where TabList is a list of tables that is to be cleared before the records from the backup are inserted. That is, all records in the tables are deleted before the tables are restored. Schema information about the tables is not cleared or read from the backup.
4. {keep_tables, TabList}, where TabList is a list of tables that is not to be cleared before the records from the backup are inserted. That is, the records in the backup are added to the records in the table. Schema information about the tables is not cleared or read from the backup.
5. {recreate_tables, TabList}, where TabList is a list of tables that is to be recreated before the records from the backup are inserted. The tables are first deleted and then created with the schema information from the backup. All the nodes in the backup need to be operational.
6. {default_op, Operation}, where Operation is either of the operations skip_tables, clear_tables, keep_tables, or recreate_tables. The default operation specifies which operation that is to be used on tables from the backup that is not specified in any of the mentioned lists. If omitted, operation clear_tables is used.

The affected tables are write-locked during the restoration. However, regardless of the lock conflicts caused by this, the applications can continue to do their work while the restoration is being performed. The restoration is performed as one single transaction.

If the database is huge, it it not always possible to restore it online. In such cases, restore the old database by installing a fallback and then restart.

Example:

  MnesiaAssistant.BackupAndRestore.restore(
    "/tmp/mnesia_backup", [{:skip_tables, [Person]}]
  )

Sets master nodes for mnesia.

For each table Mnesia determines its replica nodes (TabNodes) and starts mnesia:set_master_nodes(Tab, TabMasterNodes). where TabMasterNodes is the intersection of MasterNodes and TabNodes. For semantics, see mnesia:set_master_nodes/2.

Example

  MnesiaAssistant.BackupAndRestore.set_master_nodes([node()])

Iterates over a backup, either to transform it into a new backup, or read it. The arguments are explained briefly here. For details, see the User's Guide.

• SourceMod and TargetMod are the names of the modules that actually access the backup media.
• Source and Target are opaque data used exclusively by modules SourceMod and TargetMod to initialize the backup media.
• Acc is an initial accumulator value.
• Fun(BackupItems, Acc) is applied to each item in the backup. The Fun must return a tuple {BackupItems,NewAcc}, where BackupItems is a list of valid backup items, and NewAcc is a new accumulator value. The returned backup items are written in the target backup.
• LastAcc is the last accumulator value. This is the last NewAcc value that was returned by Fun.

The :mnesia.traverse_backup/4 function in Mnesia is designed for traversing and processing the contents of a Mnesia backup file. This functionality is particularly useful when you need to inspect, analyze, or selectively restore data from a backup. The traverse_backup function allows you to specify callback functions that will be called with the data from the backup, enabling you to programmatically interact with the backup contents.

  traverse_backup(Src :: term(), Dest :: term(), Fun, Acc) ->
  traverse_backup(Src :: term(), SrcMod :: module(), Dest :: term(), DestMod :: module(), Fun, Acc)

Example:

  initial_acc = []  # Initial value for the accumulator

  MnesiaAssistant.BackupAndRestore.traverse_backup(
    source,
    dest,
    &BackupTraversal.table_fun/2,
    initial_acc
  )
  # OR
  MnesiaAssistant.BackupAndRestore.traverse_backup(
    source,
    source_module,
    dest,
    dest_module
    &BackupTraversal.table_fun/2,
    initial_acc
  )

Read traverse_backup/4 document.

Deinstalls a fallback before it has been used to restore the database. This is normally a distributed operation that is either performed on all nodes with disc resident schema, or none.

Uninstallation of fallbacks requires Erlang to be operational on all involved nodes, but it does not matter if Mnesia is running or not. Which nodes that are considered as disc-resident nodes is determined from the schema information in the local fallback.

 Args = [{mnesia_dir, Dir :: string()}]
 {module, BackupMod}. For semantics, see mnesia:install_fallback/2.
 {scope, Scope}. For semantics, see mnesia:install_fallback/2.
 {mnesia_dir, AlternateDir}. For semantics, see mnesia:install_fallback/2.

Example:

  MnesiaAssistant.BackupAndRestore.uninstall_fallback()
  # --> :mnesia.uninstall_fallback()
  MnesiaAssistant.BackupAndRestore.uninstall_fallback(args)
  # --> :mnesia.uninstall_fallback(args)

Read uninstall_fallback/0 document.