==== 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 to mysqlbinlog ====
--flashback (-B)
It will let mysqlbinlog to work on FLASHBACK mode.
==== New Arguments to mysqld ====
--flashback
Setup the server to use flashback. This enables binary log in row mode
and will enable extra logging for DDL's needed by flashback feature
==== 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.
For example:
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.
For example:
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.
For example:
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.
For example:
Most notably, this includes MDEV-11623, which includes a fix and
an upgrade procedure for the InnoDB file format incompatibility
that is present in MariaDB Server 10.1.0 through 10.1.20.
In other words, this merge should address
MDEV-11202 InnoDB 10.1 -> 10.2 migration does not work
Contains also
MDEV-10547: Test multi_update_innodb fails with InnoDB 5.7
The failure happened because 5.7 has changed the signature of
the bool handler::primary_key_is_clustered() const
virtual function ("const" was added). InnoDB was using the old
signature which caused the function not to be used.
MDEV-10550: Parallel replication lock waits/deadlock handling does not work with InnoDB 5.7
Fixed mutexing problem on lock_trx_handle_wait. Note that
rpl_parallel and rpl_optimistic_parallel tests still
fail.
MDEV-10156 : Group commit tests fail on 10.2 InnoDB (branch bb-10.2-jan)
Reason: incorrect merge
MDEV-10550: Parallel replication can't sync with master in InnoDB 5.7 (branch bb-10.2-jan)
Reason: incorrect merge
This makes it easier to setup master as on only have to set --log-bin.
Before this patch if one did set up the master with just --log-bin, slaves
could not connect until server_id was set on the master, which could be
both confusing and hard to do.
Moved checking whether the limit set for the number of iterations
when executing a recursive query has been reached from
st_select_lex_unit::exec_recursive to TABLE_LIST::fill_recursive.
Changed the name of the system variable max_recursion_level for
max_recursive_iterations.
Adjusted test cases.
Post-fix #2:
- Update test results
- Make the optimization conditional under @@optimizer_switch flag.
- The optimization is now disabled by default, so .result files
are changed back to be what they were before the MDEV-8989 patch.
Added test cases to check the fix.
Fixed the problem of wrong types of recursive tables when the type of anchor part does not coincide with the
type of recursive part.
Prevented usage of marerialization and subquery cache for subqueries with recursive references.
Introduced system variables 'max_recursion_level'.
Added a test case to test usage of this variable.
Added the check whether there are set functions in the specifications of recursive CTE.
Added the check whether there are recursive references in subqueries.
Introduced boolean system variable 'standards_compliant_cte'. By default it's set to 'on'.
When it's set to 'off' non-standard compliant CTE can be executed.
Added 5 minute timeout before automaticlally removing threads from thread
cache.
This solves a problem with jemalloc, which is slow with a small
thread cache and also makes thread_cache big enough that most users
doesn't have to touch it
