The reason of the bug is in that `get_var_with_binlog' performs missed
assingment of
the variables as side-effect. Doing that it eventually calls
`free_underlaid_joins' to pass as an argument `thd->lex->select_lex' of the lex
which belongs to the user query, not
to one which is emulated i.e SET @var1:=NULL.
`get_var_with_binlog' is refined to supply a temporary lex to sql_set_variables's stack.
In mysqlbinlog, there was a problem with how we escaped the content of a string user variable.
To be perfect, we should have escaped with character_set_client. But this charset is unknown
to mysqlbinlog. So the simplest is to print the string in hex. This is unreadable but
100% safe with any charset (checked with Bar), no more need to bother with character_set_client.
by binlogging some SET ONE_SHOT CHARACTER_SETetc,
which will be enough until we have it more compact and more complete in 5.0. With the present patch,
replication will work ok between 4.1.3 master and slaves, as long as:
- master and slave have the same GLOBAL.COLLATION_SERVER
- COLLATION_DATABASE and CHARACTER_SET_DATABASE are not used
- application does not use the fact that table is created with charset of the USEd db (BUG#2326).
all of which are not too hard to fulfill.
ONE_SHOT is reserved for internal use of mysqlbinlog|mysql and works only for charsets,
so we give error if used for non-charset vars.
Fix for BUG#3875 "mysqlbinlog produces wrong ouput if query uses
variables containing quotes" and BUG#3943 "Queries with non-ASCII literals are not replicated
properly after SET NAMES".
Detecting that master and slave have different global charsets or server ids.
When an update query is to be written to the binlog, and it reads unset
user variables (example: INSERT INTO t VALUEs(@a) where @a does not exist),
we create the variable like if it had been set with SET before, and we loop
(i.e. we redo the steps of logging, now that the variable exists).
Increased some tests' robustness a bit :
- Added RESET MASTER to all tests who do SHOW BINLOG EVENTS, to make them independent from previous tests.
- Added save_master_pos to these tests to wait for the slave to start before purging its binary logs.
