An implementation exists which needs to be
- ported to MariaDB Server 10.2.
- tested with 10.2
- mysqlbinlog changes need to be tested against 10.2
This Sub-Tasks does not cover new implementations to be able to "undo" DDL based changes.
==== Description ====
Flashback can rollback the instances/databases/tables to an old snapshot.
It's implement on Server-Level by full image format binary logs (--binlog-row-image=FULL), so it supports all engines.
Currently, it’s a feature inside mysqlbinlog tool (with --flashback arguments).
Because the flashback binlog events will store in the memory, you should check if there is enough memory in your machine.
==== New Arguments ====
It will let mysqlbinlog to work on FLASHBACK mode.
==== Example ====
I have a table "t" in database "test", we can compare the output with "--flashback" and without.
- client/mysqlbinlog /data/mysqldata_10.0/binlog/mysql-bin.000001 -vv -d test -T t --start-datetime="2013-03-27 14:54:00" > /tmp/1.sql
- client/mysqlbinlog /data/mysqldata_10.0/binlog/mysql-bin.000001 -vv -d test -T t --start-datetime="2013-03-27 14:54:00" -B > /tmp/2.sql
Then, importing the output flashback file (/tmp/2.log), it can flashback your database/table to the special time (--start-datetime).
And if you know the exact postion, " – start-postion " is also works, mysqlbinlog will output the flashback logs that can flashback to " – start-postion " position.
==== Implement ====
1. As we know, if binlog_format is ROW (binlog-row-image=FULL in 10.1 and later), all columns value are store in the row event, so we can get the data before mis-operation.
2. Just do following things:
2.1 Change Event Type, INSERT->DELETE, DELETE->INSERT.
INSERT INTO t VALUES ( ... ) ---> DELETE FROM t WHERE ...
DELETE FROM t ... ---> INSERT INTO t VALUES ( ... )
2.2 For Update_Event, swapping the SET part and WHERE part.
UPDATE t SET cols1 = vals1 WHERE cols2 = vals2
UPDATE t SET cols2 = vals2 WHERE cols1 = vals1
2.3 For Multi-Rows Event, reverse the rows sequence, from the last row to the first row.
DELETE FROM t WHERE id=1; DELETE FROM t WHERE id=2; ... ; DELETE FROM t WHERE id=n;
DELETE FROM t WHERE id=n; ... ; DELETE FROM t WHERE id=2; DELETE FROM t WHERE id=1;
2.4 Output those events from the last one to the first one which mis-operation happened.
Evnet(1); Event(2); ... ; Event( n );
Event( n ); ... ; Event(2); EVent(1);
2.5 Import the output file, then all the data will be recovered by inverse operations of mis-oprerations.