Semi-sync status were not reset by FLUSH STATUS, this was because
all semi-sync status variables are defined as SHOW_FUNC and FLUSH
STATUS could only reset SHOW_LONG type variables.
This problem is fixed by change all status variables that should
be reset by FLUSH STATUS from SHOW_FUNC to SHOW_LONG.
After the fix, the following status variables will be reset by
FLUSH STATUS:
Rpl_semi_sync_master_yes_tx
Rpl_semi_sync_master_no_tx
Note: normally, FLUSH STATUS itself will be written into binlog
and be replicated, so after FLUSH STATS, one of
Rpl_semi_sync_master_yes_tx
Rpl_semi_sync_master_no_tx
can be 1 dependent on the semi-sync status. So it's recommended
to use FLUSH NO_WRITE_TO_BINLOG STATUS to avoid this.
Semi-sync uses an extra connection from slave to master to send
replies, this is a normal client connection, and used a normal
SET query to set the reply information on master, which is visible
to user and may cause some confusion and complaining.
This problem is fixed by using the method of sending reply by
using the same connection that is used by master dump thread to
send binlog to slave. Since now the semi-sync plugins are integrated
with the server code, it is not a problem to use the internal net
interfaces to do this.
The master dump thread will mark the event requires a reply and
wait for the reply when the event just sent is the last event
of a transaction and semi-sync status is ON; And the slave will
send a reply to master when it received such an event that requires
a reply.
Original revision in 6.0:
------------------------------------------------------------
revno: 2630.13.11
committer: Alexander Nozdrin <alik@mysql.com>
branch nick: 6.0-rt-wl4300
timestamp: Thu 2008-07-24 11:44:21 +0400
message:
A patch for WL#4300: Define privileges for tablespaces.
------------------------------------------------------------
per-file messages:
mysql-test/r/grant.result
Update result file: new columm 'Create_tablespace_priv' has been added to mysql.user.
mysql-test/r/ps.result
Update result file: new columm 'Create_tablespace_priv' has been added to mysql.user.
mysql-test/r/system_mysql_db.result
Update result file: new columm 'Create_tablespace_priv' has been added to mysql.user.
mysql-test/suite/falcon/r/falcon_tablespace_priv.result
Test case for WL#4300.
mysql-test/suite/falcon/t/falcon_tablespace_priv.test
Test case for WL#4300.
mysql-test/suite/ndb/r/ndb_dd_ddl.result
Test case for WL#4300.
mysql-test/suite/ndb/t/ndb_dd_ddl.test
Test case for WL#4300.
scripts/mysql_system_tables.sql
New columm 'Create_tablespace_priv' has been added to mysql.user.
scripts/mysql_system_tables_data.sql
'CREATE TABLESPACE' is granted by default to the root user.
scripts/mysql_system_tables_fix.sql
Grant 'CREATE TABLESPACE' privilege during system table upgrade
if a user had SUPER privilege.
sql/sql_acl.cc
Added CREATE TABLESPACE privilege.
sql/sql_acl.h
Added CREATE TABLESPACE privilege.
sql/sql_parse.cc
Check global 'CREATE TABLESPACE' privilege for the following SQL statements:
- CREATE | ALTER | DROP TABLESPACE
- CREATE | ALTER | DROP LOGFILE GROUP
sql/sql_show.cc
Added CREATE TABLESPACE privilege.
sql/sql_yacc.yy
Added CREATE TABLESPACE privilege.
strict SQL mode
The problem was that a COMMENT longer than 64 characters
caused CREATE PROCEDURE to fail.
This patch fixed the problem by changing the COMMENT field in
mysql.proc from char(64) to text. The corresponding ROUTINE_COMMENT
field in INFORMATION_SCHEMA.ROUTINES is also changed from
varchar(64) to longtext.
mysql_system_tables.sql and mysql_system_tables_fix.sql updated.
Test case added to sp.test and affected result-files updated.
InnoDB specified.
NO_ENGINE_SUBSTITUTION added to TRADITIONAL sql mode to prevent
silent conversions from InnoDB to MyISAM in that sql mode.
A number of test case results files updated to reflect this change.
Test added to sql_mode.test that checks that TRADITIONAL really
includes NO_ENGINE_SUBSTITUION.
mysql-test/t/ctype_utf8.test:
This test lacked "--source include/have_innodb.inc" which meant that
a number of DDL statements with engine=innodb in reality were using
myisam. "--disable_warnings" around all such statements, meant that
these engine substitutions were not visible. Test case has been
updated to include have_innodb.inc and "--disable_warnings" have been
removed for the relevant DDL statements.
From r5917 to r5940
Detailed revision comments:
r5917 | marko | 2009-09-16 04:56:23 -0500 (Wed, 16 Sep 2009) | 1 line
branches/zip: innobase_get_cset_width(): Cache the value of current_thd.
r5919 | vasil | 2009-09-16 13:37:13 -0500 (Wed, 16 Sep 2009) | 4 lines
branches/zip:
Whitespace cleanup in the ChangeLog.
r5920 | vasil | 2009-09-16 13:47:22 -0500 (Wed, 16 Sep 2009) | 4 lines
branches/zip:
Add ChangeLog entries for r5916.
r5922 | marko | 2009-09-17 01:32:08 -0500 (Thu, 17 Sep 2009) | 4 lines
branches/zip: innodb-zip.test: Make the test work with zlib 1.2.3.3.
Apparently, the definition of compressBound() has slightly changed.
This has been filed as Mantis Issue #345.
r5924 | vasil | 2009-09-17 23:59:30 -0500 (Thu, 17 Sep 2009) | 4 lines
branches/zip:
White space and formatting cleanup in the ChangeLog
r5934 | vasil | 2009-09-18 12:06:46 -0500 (Fri, 18 Sep 2009) | 4 lines
branches/zip:
Fix typo.
r5935 | calvin | 2009-09-18 16:08:02 -0500 (Fri, 18 Sep 2009) | 6 lines
branches/zip: fix bug#44338; minor non-functional changes
Bug#44338 innodb has message about non-existing option
innodb_max_files_open. Change the option to innodb_open_files.
The fix was committed into 6.0 branch.
r5938 | calvin | 2009-09-19 02:14:25 -0500 (Sat, 19 Sep 2009) | 41 lines
branches/zip: Merge revisions 2584:2956 from branches/6.0,
except c2932.
Bug#37232 and bug#31183 were fixed in the 6.0 branch only.
They should be fixed in the plugin too, specially MySQL 6.0
is discontinued at this point.
------------------------------------------------------------------------
r2604 | inaam | 2008-08-21 09:37:06 -0500 (Thu, 21 Aug 2008) | 8 lines
branches/6.0 bug#37232
Relax locking behaviour for REPLACE INTO t SELECT ... FROM t1.
Now SELECT on t1 is performed as a consistent read when the isolation
level is set to READ COMMITTED.
Reviewed by: Heikki
------------------------------------------------------------------------
r2605 | inaam | 2008-08-21 09:59:33 -0500 (Thu, 21 Aug 2008) | 7 lines
branches/6.0
Added a comment to clarify why distinct calls to read MySQL binary
log file name and log position do not entail any race condition.
Suggested by: Heikki
------------------------------------------------------------------------
r2956 | inaam | 2008-11-04 04:47:30 -0600 (Tue, 04 Nov 2008) | 11 lines
branches/6.0 bug#31183
If the system tablespace runs out of space because 'autoextend' is
not specified with innodb_data_file_path there was no error message
printed to the error log. The client would get 'table full' error.
This patch prints an appropriate error message to the error log.
rb://43
Approved by: Marko
------------------------------------------------------------------------
r5940 | vasil | 2009-09-21 00:26:04 -0500 (Mon, 21 Sep 2009) | 4 lines
branches/zip:
Add ChangeLog entries for c5938.
To-number conversion warnings work differenly with CHAR
and VARCHAR sp variables.
The original revision-IDs are:
staale.smedseng@sun.com-20081124095339-2qdvzkp0rn1ljs30staale.smedseng@sun.com-20081125104611-rtxic5d12e83ag2o
The patch provides ER_TRUNCATED_WRONG_VALUE warning messages
for conversion of VARCHAR to numberic values, in line with
messages provided for CHAR conversions. Conversions are
checked for success, and the message is emitted in case
failure.
The tests are amended to accept the added warning messages,
and explicit conversion of ON/OFF values is added for
statements checking system variables. In test
rpl.rpl_switch_stm_row_mixed checking for warnings is
temporarily disabled for one statement, as this generates
warning messages for strings that vary between executions.
sql/field.cc:
The pushing of the truncation warning is now done in a
separate static function, and used in various places.
mysql-test/suite/rpl/r/rpl_stop_middle_group.result:
the new result file
mysql-test/suite/rpl/t/rpl_stop_middle_group.test:
renamed from rpl_row_stop_middle_update and added a regression test for bug#45940.
From revision r5703 to r5716
Detailed revision comments:
r5703 | marko | 2009-08-27 02:25:00 -0500 (Thu, 27 Aug 2009) | 41 lines
branches/zip: Replace the constant 3/8 ratio that controls the LRU_old
size with the settable global variable innodb_old_blocks_pct. The
minimum and maximum values are 5 and 95 per cent, respectively. The
default is 100*3/8, in line with the old behavior.
ut_time_ms(): New utility function, to return the current time in
milliseconds. TODO: Is there a more efficient timestamp function, such
as rdtsc divided by a power of two?
buf_LRU_old_threshold_ms: New variable, corresponding to
innodb_old_blocks_time. The value 0 is the default behaviour: no
timeout before making blocks 'new'.
bpage->accessed, bpage->LRU_position, buf_pool->ulint_clock: Remove.
bpage->access_time: New field, replacing bpage->accessed. Protected by
buf_pool_mutex instead of bpage->mutex. Updated when a page is created
or accessed the first time in the buffer pool.
buf_LRU_old_ratio, innobase_old_blocks_pct: New variables,
corresponding to innodb_old_blocks_pct
buf_LRU_old_ratio_update(), innobase_old_blocks_pct_update(): Update
functions for buf_LRU_old_ratio, innobase_old_blocks_pct.
buf_page_peek_if_too_old(): Compare ut_time_ms() to bpage->access_time
if buf_LRU_old_threshold_ms && bpage->old. Else observe
buf_LRU_old_ratio and bpage->freed_page_clock.
buf_pool_t: Add n_pages_made_young, n_pages_not_made_young,
n_pages_made_young_old, n_pages_not_made_young, for statistics.
buf_print(): Display buf_pool->n_pages_made_young,
buf_pool->n_pages_not_made_young. This function is only for crash
diagnostics.
buf_print_io(): Display buf_pool->LRU_old_len and quantities derived
from buf_pool->n_pages_made_young, buf_pool->n_pages_not_made_young.
This function is invoked by SHOW ENGINE INNODB STATUS.
rb://129 approved by Heikki Tuuri. This addresses Bug #45015.
r5704 | marko | 2009-08-27 03:31:17 -0500 (Thu, 27 Aug 2009) | 32 lines
branches/zip: Fix a critical bug in fast index creation that could
corrupt the created indexes.
row_merge(): Make "half" an in/out parameter. Determine the offset of
half the output file. Copy the last blocks record-by-record instead of
block-by-block, so that the records can be counted. Check that the
input and output have matching n_rec.
row_merge_sort(): Do not assume that two blocks of size N are merged
into a block of size 2*N. The output block can be shorter than the
input if the last page of each input block is almost empty. Use an
accurate termination condition, based on the "half" computed by
row_merge().
row_merge_read(), row_merge_write(), row_merge_blocks(): Add debug output.
merge_file_t, row_merge_file_create(): Add n_rec, the number of records
in the merge file.
row_merge_read_clustered_index(): Update n_rec.
row_merge_blocks(): Update and check n_rec.
row_merge_blocks_copy(): New function, for copying the last blocks in
row_merge(). Update and check n_rec.
This bug was discovered with a user-supplied test case that creates an
index where the initial temporary file is 249 one-megabyte blocks and
the merged files become smaller. In the test, possible merge record
sizes are 10, 18, and 26 bytes.
rb://150 approved by Sunny Bains. This addresses Issue #320.
r5705 | marko | 2009-08-27 06:56:24 -0500 (Thu, 27 Aug 2009) | 11 lines
branches/zip: dict_index_find_cols(): On column name lookup failure,
return DB_CORRUPTION (HA_ERR_CRASHED) instead of abnormally
terminating the server. Also, disable the previously added diagnostic
output to the error log, because mysql-test-run does not like extra
output in the error log. (Bug #44571)
dict_index_add_to_cache(): Handle errors from dict_index_find_cols().
mysql-test/innodb_bug44571.test: A test case for triggering the bug.
rb://135 approved by Sunny Bains.
r5706 | inaam | 2009-08-27 11:00:27 -0500 (Thu, 27 Aug 2009) | 20 lines
branches/zip rb://147
Done away with following two status variables:
innodb_buffer_pool_read_ahead_rnd
innodb_buffer_pool_read_ahead_seq
Introduced two new status variables:
innodb_buffer_pool_read_ahead = number of pages read as part of
readahead since server startup
innodb_buffer_pool_read_ahead_evicted = number of pages that are read
in as readahead but were evicted before ever being accessed since
server startup i.e.: a measure of how badly our readahead is
performing
SHOW INNODB STATUS will show two extra numbers in buffer pool section:
pages read ahead/sec and pages evicted without access/sec
Approved by: Marko
r5707 | inaam | 2009-08-27 11:20:35 -0500 (Thu, 27 Aug 2009) | 6 lines
branches/zip
Remove unused macros as we erased the random readahead code in r5703.
Also fixed some comments.
r5708 | inaam | 2009-08-27 17:43:32 -0500 (Thu, 27 Aug 2009) | 4 lines
branches/zip
Remove redundant TRUE : FALSE from the return statement
r5709 | inaam | 2009-08-28 01:22:46 -0500 (Fri, 28 Aug 2009) | 5 lines
branches/zip rb://152
Disable display of deprecated parameter innodb_file_io_threads in
'show variables'.
r5714 | marko | 2009-08-31 01:10:10 -0500 (Mon, 31 Aug 2009) | 5 lines
branches/zip: buf_chunk_not_freed(): Do not acquire block->mutex unless
block->page.state == BUF_BLOCK_FILE_PAGE. Check that block->page.state
makes sense.
Approved by Sunny Bains over the IM.
r5716 | vasil | 2009-08-31 02:47:49 -0500 (Mon, 31 Aug 2009) | 9 lines
branches/zip:
Fix Bug#46718 InnoDB plugin incompatible with gcc 4.1 (at least: on PPC): "Undefined symbol"
by implementing our own check in plug.in instead of using the result from
the check from MySQL because it is insufficient.
Approved by: Marko (rb://154)
The issue appears when number of heartbeat events non-zero before start of test
block. But really we need to check that no new events has received during test block.
So I did following:
1. Replace absolute values by diff of values
2. Increase heartbeat period from 1.5 to 5 sec
Let
- T be a transactional table and N non-transactional table.
- B be begin, C commit and R rollback.
- N be a statement that accesses and changes only N-tables.
- T be a statement that accesses and changes only T-tables.
In RBR, changes to N-tables that happen early in a transaction are not immediately flushed
upon committing a statement. This behavior may, however, break consistency in the presence
of concurrency since changes done to N-tables become immediately visible to other
connections. To fix this problem, we do the following:
. B N N T C would log - B N C B N C B T C.
. B N N T R would log - B N C B N C B T R.
Note that we are not preserving history from the master as we are introducing a commit that
never happened. However, this seems to be more acceptable than the possibility of breaking
consistency in the presence of concurrency.
Let
- T be a transactional table and N non-transactional table.
- B be begin, C commit and R rollback.
- M be a mixed statement, i.e. a statement that updates both T and N.
- M* be a mixed statement that fails while updating either T or N.
This patch restore the behavior presented in 5.1.37 for rows either produced in
the RBR or MIXED modes, when a M* statement that happened early in a transaction
had their changes written to the binary log outside the boundaries of the
transaction and wrapped in a BEGIN/ROLLBACK. This was done to keep the slave
consistent with with the master as the rollback would keep the changes on N and
undo them on T. In particular, we do what follows:
. B M* T C would log - B M* R B T C.
Note that, we are not preserving history from the master as we are introducing a
rollback that never happened. However, this seems to be more acceptable than
making the slave diverge. We do not fix the following case:
. B T M* C would log B T M* C.
The slave will diverge as the changes on T tables that originated from the M
statement are rolled back on the master but not on the slave. Unfortunately, we
cannot simply rollback the transaction as this would undo any uncommitted
changes on T tables.
SBR is not considered in this patch because a failing statement is written to
the binary along with the error code and a slave executes and then rolls back
the statement when it has an associated error code, thus undoing the effects
on T. In RBR and MBR, a full-fledged fix will be pushed after the WL 2687.
CHANGE MASTER TO command required the value for RELAY_LOG_FILE to
be an absolute path, which was different from the requirement of
MASTER_LOG_FILE.
This patch fixed the problem by changing the value for RELAY_LOG_FILE
to be the basename of the log file as that for MASTER_LOG_FILE.
The problem is that there is only one autoinc value associated with
the query when binlogging. If more than one autoinc values are used
in the query, the autoinc values after the first one can be inserted
wrongly on slave. So these autoinc values can become inconsistent on
master and slave.
The problem is resolved by marking all the statements that invoke
a trigger or call a function that updated autoinc fields as unsafe,
and will switch to row-format in Mixed mode. Actually, the statement
is safe if just one autoinc value is used in sub-statement, but it's
impossible to check how many autoinc values are used in sub-statement.)
mysql-test/suite/rpl/r/rpl_auto_increment_update_failure.result:
Test result for bug#45677
mysql-test/suite/rpl/t/rpl_auto_increment_update_failure.test:
Added test to verify the following two properties:
P1) insert/update in an autoinc column causes statement to
be logged in row format if binlog_format=mixed
P2) if binlog_format=mixed, and a trigger or function contains
two or more inserts/updates in a table that has an autoinc
column, then the slave should not go out of sync, even if
there are concurrent transactions.
sql/sql_base.cc:
Added function 'has_write_table_with_auto_increment' to check
if one (or more) write tables have auto_increment columns.
Removed function 'has_two_write_locked_tables_with_auto_increment',
because the function is included in function
'has_write_table_with_auto_increment'.
rpl_slave_skip fails randomly on PB2. This patch fixes the failure by
setting explicit wait for SQL thread to stop, instead of the
wait_for_slave_to_stop mysqltest command, after a start until command
is executed.
We cann connect() in a non-blocking mode to be able to specify a
non-standard timeout.
The problem was that we did not fetch the status from the
non-blocking connect(). We assumed that poll() would not return
a POLLIN flag if the connect failed. But on some platforms this
is not true.
After a successful poll() we do now retrieve the status value
from connect() with getsockopt(...SO_ERROR...). Now we do know
if (and how) the connect failed.
The test case for my investigation was rpl.rlp_ssl1 on an
Ubuntu 9.04 x86_64 machine. Both, IPV4 and IPV6 were active.
'localhost' resolved first for IPV6 and then for IPV4. The
connection over IPV6 was blocked. rpl.rlp_ssl1 timed out
as it did not notice the failed connect(). The first read()
failed, which was interpreted as a master crash and the
connection was tried to reestablish with the same result
until the retry limit was reached.
With the fix, the connect() problem is immediately recognized,
and the connect() is retried on the second resolution for
'localhost', which is successful.
libmysqld/libmysqld.c:
Bug#37267 - connect() EINPROGRESS failures mishandled in client library
Changed a DBUG print string to distinguish the two mysql_real_connect()
implementations in DBUG traces.
mysql-test/include/wait_for_slave_param.inc:
Bug#37267 - connect() EINPROGRESS failures mishandled in client library
Made timeout value available in error message.
mysql-test/suite/rpl/r/rpl_get_master_version_and_clock.result:
Bug#37267 - connect() EINPROGRESS failures mishandled in client library
Fixed test result. Connect error is now detected as CR_CONN_HOST_ERROR
(2003) instead of CR_SERVER_LOST (2013).
sql-common/client.c:
Bug#37267 - connect() EINPROGRESS failures mishandled in client library
Added retrieval of the error code from the non-blocking connect().
Added DBUG.
Added comment.
DECIMAL and TIMESTAMP used to have NUM_FLAG, but NEWDECIMAL was forgotten.
It's correct that TIMESTAMP does not have the flag nowadays (manual will be updated, connectors
developers will be notified).
client/mysqldump.c:
IS_NUM_FIELD(f) removed and replaced by its definition (f>flags & NUM_FLAG).
include/mysql.h:
- IS_NUM_FIELD() is removed because name is too close to IS_NUM() and it is not used a lot
- INTERNAL_NUM_FIELD() is removed:
* it forgets to test NEWDECIMAL (when IS_NUM() was updated for NEWDECIMAL we forgot
to update INTERNAL_NUM_FIELD()), that's why client didn't mark NEWDECIMAL with NUM_FLAG (a bug).
* it has an obsolete test for length of the TIMESTAMP field: test became accidentally wrong when length
of TIMESTAMP was changed to always be 19 (when the format was changed from YYYYMMDDhhmmss to
YYYY-MM-DD hh:mm:ss), never 8 or 14 anymore. That obsolete test caused TIMESTAMP to lose NUM_FLAG,
which was an accidental but good change (see below).
* IS_NUM() should be used instead
- IS_NUM(f) is changed: TIMESTAMP used to be parsable as a number without quotes (when it was formatted as
"YYYYMMDDhhmmss"); but it is not anymore (now that it is "YYYY-MM-DD hh:mm:ss"), so it should not have NUM_FLAG
(mysqldump needs to quote TIMESTAMP values), so IS_NUM() should return false for it.
libmysqld/lib_sql.cc:
use IS_NUM() instead of INTERNAL_NUM_FIELD()
mysql-test/r/bigint.result:
result change: NEWDECIMAL fields now have NUM_FLAG (32768)
mysql-test/r/metadata.result:
result change: NEWDECIMAL fields now have NUM_FLAG (32768)
mysql-test/r/mysqldump.result:
DECIMAL columns are not quoted anymore by mysqldump. Which is ok, the parser does not need '' for them
mysql-test/r/ps_2myisam.result:
result change: NEWDECIMAL fields now have NUM_FLAG (32768)
mysql-test/r/ps_3innodb.result:
result change: NEWDECIMAL fields now have NUM_FLAG (32768)
mysql-test/r/ps_4heap.result:
result change: NEWDECIMAL fields now have NUM_FLAG (32768)
mysql-test/r/ps_5merge.result:
result change: NEWDECIMAL fields now have NUM_FLAG (32768)
mysql-test/suite/ndb/r/ps_7ndb.result:
result change: NEWDECIMAL fields now have NUM_FLAG (32768)
mysql-test/t/metadata.test:
test for BUG#42980
sql-common/client.c:
use IS_NUM() instead of INTERNAL_NUM_FIELD()
The 'BEGIN/COMMIT/ROLLBACK' log event could be filtered out if the
database is not selected by --database option of mysqlbinlog command.
This can result in problem if there are some statements in the
transaction are not filtered out.
To fix the problem, mysqlbinlog will output 'BEGIN/ROLLBACK/COMMIT'
in regardless of the database filtering rules.
client/mysqlbinlog.cc:
Skip the database check for BEGIN/COMMIT/ROLLBACK log events.
mysql-test/r/mysqlbinlog.result:
Test result for bug#46998
mysql-test/suite/binlog/t/binlog_row_mysqlbinlog_db_filter.test:
The test case is updated duo to the patch of bug#46998
mysql-test/t/mysqlbinlog.test:
Added test to verify if the 'BEGIN', 'COMMIT' and 'ROLLBACK' are output
in regardless of database filtering
NOTE: Backporting the patch to next-mr.
The fix proposed in BUG#35542 and BUG#31665 introduces a performance issue
when fsyncing the master.info, relay.info and relay-log.bin* after #th events.
Although such solution has been proposed to reduce the probability of corrupted
files due to a slave-crash, the performance penalty introduced by it has
made the approach impractical for highly intensive workloads.
In a nutshell, the option --syn-relay-log proposed in BUG#35542 and BUG#31665
simultaneously fsyncs master.info, relay-log.info and relay-log.bin* and
this is the main source of performance issues.
This patch introduces new options that give more control to the user on
what should be fsynced and how often:
1) (--sync-master-info, integer) which syncs the master.info after #th event;
2) (--sync-relay-log, integer) which syncs the relay-log.bin* after #th
events.
3) (--sync-relay-log-info, integer) which syncs the relay.info after #th
transactions.
To provide both performance and increased reliability, we recommend the following
setup:
1) --sync-master-info = 0 eventually the operating system will fsync it;
2) --sync-relay-log = 0 eventually the operating system will fsync it;
3) --sync-relay-log-info = 1 fsyncs it after every transaction;
Notice, that the previous setup does not reduce the probability of
corrupted master.info and relay-log.bin*. To overcome the issue, this patch also
introduces a recovery mechanism that right after restart throws away relay-log.bin*
retrieved from a master and updates the master.info based on the relay.info:
4) (--relay-log-recovery, boolean) which enables a recovery mechanism that
throws away relay-log.bin* after a crash.
However, it can only recover the incorrect binlog file and position in master.info,
if other informations (host, port password, etc) are corrupted or incorrect,
then this recovery mechanism will fail to work.
