BUG#2826 "Seconds behind master weirdness"
(sometimes this column of SHOW SLAVE STATUS shows a very big value,
in fact a small negative number casted to ulonglong).
This problem was reported by only one user, but which uses
synchronized time between his servers.
As suggested by the user, to hide this I display max(0, the value)
so that it will be less confusing. For a user, seeing 0 is probably
better than seeing -1 (both tell you that the slave is very close
to the master).
we change THD::system_thread from a 'bool' to a bitmap to be able to
distinguish between delayed-insert threads and slave threads.
- Fix for BUG#1701 "Update from multiple tables" (one line in sql_parse.cc,
plus a new test rpl_multi_update.test). That's just adding an initialization.
The problem was that when the slave SQL thread reads a hot relay log (hot = the one being written to by the
slave I/O thread), it must have the LOCK_log. It already took it for read_log_event(), but needs
it also for check_binlog_magic().
This should fix all recently reported failures of the rpl_max_relay_size test in 4.1 and 5.0
(though the bug exists since 4.0, it showed up first in 5.0).
the relay log before flushing master.info.
Doing 'before' leads to duplicate event, doing after leads to missing event.
Both can be as destructive, but 'duplicate' enables us to later add detection
code to catch it. Whereas 'missing' can't be caught (it can't, because
the I/O thread can produce legal position jumps, for example if it has
ignored an event coming from this slave (rememember that starting from 4.1.1,
the I/O thread filters the server id).
Now the I/O thread (in flush_master_info()) flushes the relay log to disk
after reading every event. Slower but provides additionnal safety in case
of brutal crash.
I had to make the flush optional (i.e. add a if(some_bool_argument) in the function)
because sometimes flush_master_info() is called when there is no usable
relay log (the relay log's IO_CACHE is not initialized so can't be flushed).
(Initial caps for each word.) For example, instead of writing
Until_condition, Until_Log_File, and Until_log_pos, write
Until_Condition, Until_Log_File, and Until_Log_pos.
rli->save_temporary_tables and slave_open_temp_tables
(in old 4.0 you could make "SHOW STATUS LIKE 'slave_open_temp_tables'" grow
indefinitely by doing RESET SLAVE and replicating always the same CREATE
TEMPORARY TABLE).
It's critical to reset save_temporary_tables to 0 (otherwise you may later
read memory which has been freed) so this changeset should go into 4.1.
- when we don't have in_addr_t, use uint32.
- a forgotten initialization of slave_proxy_id in sql/log_event.cc (was not really "forgot", was
"we needn't init it there", but there was one case where we needed...).
- made slave_proxy_id always meaningful in THD and Log_event, so we can
rely more on it (no need to test if it's meaningful). THD::slave_proxy_id
is equal to THD::thread_id except for the slave SQL thread.
- clean up the slave's temporary table (i.e. free their memory) when slave
server shuts down.
"If 2 master threads with same-name temp table, slave makes bad binlog"
and (two birds with one stone) for
BUG#1240 "slave of slave breaks when STOP SLAVE was issud on parent slave
and temp tables".
Here is the design change:
in a slave running with --log-slave-updates, events are now logged with the
thread id they had on the master. So no more id conflicts between master threads,
but introduces id conflicts between one master thread and one normal
client thread connected to the slave. This is solved by storing the server id
in the temp table's name.
New test which requires mysql-test-run to be run with --manager,
otherwise it will be skipped.
Undoing a Monty's change (hum, a chill runs down my spine ;) which was
"Cleanup temporary tables when slave ends" in ChangeSet 1.1572.1.1.
a Format_description_log_event (or maybe it will be named
Description_log_event) which is not recognized by 4.0, so
a 4.0 can't be a slave of 5.0. We detect it early to produce
a helpful message instead of "corrupted relay log" later.
"Add a column "Timestamp_of_last_master_event_executed" in SHOW SLAVE STATUS".
Finally this is adding
- Slave_IO_State (a copy of the State column of SHOW PROCESSLIST for the I/O thread,
so that the users, most of the time, has enough info with only SHOW SLAVE STATUS).
- Seconds_behind_master. When the slave connects to the master it does SELECT UNIX_TIMESTAMP()
on the master, computes the absolute difference between the master's and the slave's clock.
It records the timestamp of the last event executed by the SQL thread, and does a
small computation to find the number of seconds by which the slave is late.
Now LOAD DATA FROM MASTER does not drop the database, instead it only tries to
create it, and drops/creates table-by-table.
* replicate_wild_ignore_table='db1.%' is now considered as "ignore the 'db1'
database as a whole", as it already works for CREATE DATABASE and DROP DATABASE.
Added proper options to CHANGE MASTER TO, new fields to SHOW SLAVE STATUS,
Honoring this parameters during connection to master.
Introduced new format of master.info file
For example the Binlog_dump thread (on the master) sometimes showed "Slave:".
And there were confusing messages where "binlog" was employed instead
of "relay log".
