Name
backup, backup_close, backup_flush, backup_prepare, backup_row — Write data into transaction log format for backup purposes. Deprecated.
Synopsis
backup
(
|
in
file
varchar
); |
backup_close
(
|
); |
backup_flush
(
|
); |
backup_prepare
(
|
in
file
varchar
); |
backup_row
(
|
in
row
any
); |
Description
![[Important]](images/important.png)
|
Important |
|---|---|
|
These functions are deprecated. The use of backup_online () is preferred for database backups. Performing a backup with the destination file /dev/null is a good way of verifying a database's physical integrity.
All backup files, whether complete (created with
Backup and log files contain assumptions about the schema and row layout of the database. Hence it is not possible to use these for transferring data between databases. Attempt to do so will result in unpredictable results. Thus a log or backup may only be replayed on the same database, an empty database or a copy of the database which has had no schema changed since it was made. Also, when replaying a backup file onto an empty database, the +replay-crash-dump switch should be given on the executable command line. |
This function requires dba privileges.
Full backup
The backup function takes a file name as argument.
The file produced will be in the log format and will recreate the
database as it was at the time of the last checkpoint when replayed on
an empty database. Such a file cannot be replayed on anything except an
empty database. Logs made after the backup can be replayed over the
database resulting from the backup file's replay. No schema operations
are allowed between replays.
Partial backups
The backup_prepare, backup_row
and backup_close operations allow making specific
partial backups.
-
backup_prepare -
backup_prepareinitiates the backup. This must be the first statement to execute in its transaction. The rest of the transaction will be a read only snapshot view of the state as of the last checkpoint. Checkpointing is disabled untilbackup_closeis called.
Checkpoints are disabled for the time between
backup_prepare and
backup_close. The backup transaction being
lock-free, it cannot die of deadlock and hence will stay open for the
duration of the backup.
-
backup_row -
backup_rowwrites the row given as parameter into the backup file that was associated to the current transaction by a priorbackup_prepare. The row must be obtained obtained by selecting the pseudo column_ROWfrom any table. -
backup_flush -
The
backup_flushfunction will insert a transaction boundary into the backup log. All rows backed up between twobackup_flushcalls will be replayed as a single transaction by replay. Having long intervals betweenbackup_flushcalls will cause significant memory consumption at replay time for undo logs. -
backup_close -
The
backup_closefunction terminates the backup and closes the file. The transaction remains a read only snapshot of the last checkpoint but checkpoints are now re-enabled. The transaction should be committed or rolled back afterbackup_close.
Parameters
file
varchar file filename for the
generated log.
backup_row
any row a value of the pseudo column
_ROW.