Commit 1c3dc887 authored by sasha@mysql.sashanet.com's avatar sasha@mysql.sashanet.com
Browse files

fixed mysterious offset confusion bug 

added a test case for it - took some creative work to figure out
how to make it happen at will
updated the manual
parent 0fb2e24a

Docs/manual.texi

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@@ -6543,8 +6543,8 @@ shell> make 














A collection of our standard configure scripts is located in the















@file{BUILD/} subdirectory.  If you are lazy, you can use













@file{BUILD/compile-pentium-debug}.  It will actually work on a lot of













non-x86 machines despite its name.













@file{BUILD/compile-pentium-debug}. To compile on a different architecture,













modify the script removing flags that are Pentium-specific.





























@item















When the build is done, run @code{make install}.  Be careful with this










@@ -29828,8 +29828,11 @@ query from the master.













@item















If you have decided you can skip the next query, do















@code{SET SQL_SLAVE_SKIP_COUNTER=1; SLAVE START;} to skip a query that













does not use auto_increment, last_insert_id or timestamp, or













@code{SET SQL_SLAVE_SKIP_COUNTER=2; SLAVE START;} otherwise













does not use auto_increment, or last_insert_id  or













@code{SET SQL_SLAVE_SKIP_COUNTER=2; SLAVE START;} otherwise. The reason













auto_increment/last_insert_id queries are different is that they take













two events in the binary log of the master.



























@item















If you are sure the slave started out perfectly in sync with the master,















and no one has updated  the tables involved outside of slave thread,










@@ -45728,6 +45731,9 @@ not yet 100% confident in this code.













@appendixsubsec Changes in release 3.23.40















@itemize @bullet















@item













Fixed bug in slave thread when under some rare circumstances it could













get 22 bytes ahead on the offset in the master













@item















Added @code{slave_wait_timeout} for replication.















@item















Fixed problem with @code{UPDATE} and BDB tables.

























mysql-test/r/rpl_mystery22.result
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mysql-test/t/rpl_mystery22.test
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# test case to make slave thread get ahead by 22 bytes



























source include/master-slave.inc;













connection master;













# first, cause a duplicate key problem on the slave













create table t1(n int auto_increment primary key);













save_master_pos;













connection slave;













sync_with_master;













insert into t1 values (2);













connection master;













insert into t1 values(NULL);













insert into t1 values(NULL);













save_master_pos;













connection slave;













sleep 1; # there is no way around this sleep - we have to wait until













# the slave tries to run the query, fails and aborts slave thread













delete from t1 where n = 2;













slave start;













sync_with_master;













#now the buggy slave would be confused on the offset but it can replicate













#in order to make it break, we need to stop/start the slave one more time













slave stop;













connection master;













# to be able to really confuse the slave, we need some non-auto-increment













# events in the log













create table t2(n int);













drop table t2;













insert into t1 values(NULL);













save_master_pos;













connection slave;













slave start;













#now the truth comes out - if the slave is buggy, it will never sync because













#the slave thread is not able to read events













sync_with_master;













select * from t1;













#clean up













connection master;













drop table t1;













save_master_pos;













connection slave;













sync_with_master;





































mysql-test/t/rpl_sporadic_master.test



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@@ -3,12 +3,19 @@





























source include/master-slave.inc;















connection master;













drop table if exists t1;













drop table if exists t1,t2;













create table t2(n int);















create table t1(n int not null auto_increment primary key);















insert into t1 values (NULL),(NULL);















delete from t1;















# We have to use 4 in the following to make this test work with all table types















insert into t1 values (4),(NULL);













save_master_pos;













connection slave;













sync_with_master;













slave stop;













slave start;













connection master;















insert into t1 values (NULL),(NULL);















flush logs;















delete from t1;









@@ -20,7 +27,7 @@ connection slave;













sync_with_master;















select * from t1;















connection master;













drop table t1;













drop table t1,t2;















save_master_pos;















connection slave;















sync_with_master;
























sql/slave.cc



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@@ -1222,6 +1222,8 @@ pthread_handler_decl(handle_slave,arg __attribute__((unused)))













  thd->thread_stack = (char*)&thd; // remember where our stack is















  thd->temporary_tables = save_temporary_tables; // restore temp tables















  threads.append(thd);













  glob_mi.pending = 0;  //this should always be set to 0 when the slave thread













  // is started















  















  DBUG_PRINT("info",("master info: log_file_name=%s, position=%s",















		     glob_mi.log_file_name, llstr(glob_mi.pos,llbuff)));