The code to get read the value of a system variable was extracting its value
on PREPARE stage and was substituting the value (as a constant) into the parse tree.
Note that this must be a reversible transformation, i.e. it must be reversed before
each re-execution.
Unfortunately this cannot be reliably done using the current code, because there are
other non-reversible source tree transformations that can interfere with this
reversible transformation.
Fixed by not resolving the value at PREPARE, but at EXECUTE (as the rest of the
functions operate). Added a cache of the value (so that it's constant throughout
the execution of the query). Note that the cache also caches NULL values.
Updated an obsolete related test suite (variables-big) and the code to test the
result type of system variables (as per bug 74).
Adds --general_log_file, --slow_query_log_file command-
line options to match system variables of the same names.
Deprecates --log, --log-slow-queries command-line options
and log, log_slow_queries system-variables for v7.0; they
are superseded by general_log/general_log_file and
slow_query_log/slow_query_log_file, respectively.
SUPER is not required to change binlog format for session
A user without SUPER privileges can change the value of the
session variable BINLOG_FORMAT, causing problems for a DBA.
This changeset requires a user to have SUPER privileges to
change the value of the session variable BINLOG_FORMAT, and
not only the global variable BINLOG_FORMAT.
The event scheduler was not designed to work in embedded mode. This
patch disables and excludes the event scheduler when the server is
compiled for embedded build.
general_log_file/slow_query_log_file.
The problem was that log file path was rejected if directory
path was empty. The fix is to reject log file path only if it
is entirely empty.
We have "set" variables, which can accept empty values
(like sql_mode), and which can not (like log_output). The problem
was that the code does not distinguish them and allow empty
values for every set variable.
The fix is to introduce an attribute of a set variable telling
whether it can accept empty values.
Problem: in mixed and statement mode, a query that refers to a
system variable will use the slave's value when replayed on
slave. So if the value of a system variable is inserted into a
table, the slave will differ from the master.
Fix: mark statements that refer to a system variable as "unsafe",
meaning they will be replicated by row in mixed mode and produce a warning
in statement mode. There are some exceptions: some variables are actually
replicated. Those should *not* be marked as unsafe.
BUG#34732: mysqlbinlog does not print default values for auto_increment variables
Problem: mysqlbinlog does not print default values for some variables,
including auto_increment_increment and others. So if a client executing
the output of mysqlbinlog has different default values, replication will
be wrong.
Fix: Always print default values for all variables that are replicated.
I need to fix the two bugs at the same time, because the test cases would
fail if I only fixed one of them.
There was no way to see if report-{host,port,user,password} were set up.
Fixed with introducing new global variables.
The variables are made read-only because of a possible need to change them
most probably require the slave server restart.
Todo: transform the startup options to be CHANGE master parameters - i.e
to deprecate `report-' options, and to change the new vars
to be updatable at time of CHANGE master executes with new
values.
Bug#34678 @@debug variable's incremental mode
The problem is that the per-thread debugging settings stack wasn't
being deallocated before the thread termination, leaking the stack
memory. The chosen solution is to push a new state if the current
is set to the initial settings and pop it (free) once the thread
finishes.
If setting a system-variable provided by a plug-in failed, no OK or
error was sent in some cases, hanging the client. We now send an error
in the case from the ticket (integer-argument out of range in STRICT
mode). We also provide a semi-generic fallback message for possible
future cases like this where an error is signalled, but no message is
sent to the client. The error/warning handling is unified so it's the
same again for variables provided by plugins and those in the server
proper.
value" error even though the value was correct): a C function in my_getopt.c
was taking bool* in parameter and was called from C++ sql_plugin.cc,
but on some Mac OS X sizeof(bool) is 1 in C and 4 in C++, giving funny
mismatches. Fixed, all other occurences of bool in C are removed, future
ones are blocked by a "C-bool-catcher" in my_global.h (use my_bool).
When set the server-id dynamically, the server_id member of current thread is not updated.
Update the server_id member of current thread after updated the global variable value.
The problem is that some DDL statements (ALTER TABLE, CREATE
TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to
momentarily drop the lock, reopen the table and grab the write
lock again (using reopen_tables). When grabbing the lock again,
reopen_tables doesn't pass a flag to mysql_lock_tables in
order to ignore the impending global read lock, which causes a
assertion because LOCK_open is being hold. Also dropping the
lock must not signal to any threads that the table has been
relinquished (related to the locking/flushing protocol).
The solution is to correct the way the table is reopenned
and the locks grabbed. When reopening the table and under
LOCK TABLES, the table version should be set to 0 so other
threads have to wait for the table. When grabbing the lock,
any other flush should be ignored because it's theoretically
a atomic operation. The chosen solution also fixes a potential
discrepancy between binlog and GRL (global read lock) because
table placeholders were being ignored, now a FLUSH TABLES WITH
READ LOCK will properly for table with open placeholders.
It's also important to mention that this patch doesn't fix
a potential deadlock if one uses two GRLs under LOCK TABLES
concurrently.
