updates

Attempt to execute trigger or stored function with multi-UPDATE
which used - but didn't update - a table that was also used by
the calling statement led to an error. Read-only reference to
tables used in the calling statement should be allowed.
 
This problem was caused by the fact that check for conflicting
use of tables in SP/triggers was performed in open_tables(),
and in case of multi-UPDATE we didn't know exact lock type at
this stage.

We solve the problem by moving this check to lock_tables(), so
it can be performed after exact lock types for tables used by
multi-UPDATE are determined.

  
UNION could convert fixed-point FLOAT(M,D)/DOUBLE(M,D) columns  
to FLOAT/DOUBLE when aggregating data types from the SELECT  
substatements. While there is nothing particularly wrong with  
this behavior, especially when M is greater than the hardware  
precision limits, it could be confusing in cases when all  
SELECT statements in a union have the same  
FLOAT(M,D)/DOUBLE(M,D) columns with equal precision  
specifications listed in the same position.  
  
Since the manual is quite vague on what data type should be  
returned in such cases, the bug was fixed by implementing the  
most 'expected' behavior: do not convert FLOAT(M,D)/DOUBLE(M,D)  
to anything else if all SELECT statements in a UNION have the  
same precision for that column.  

Problem: commit doesn't delete savepoints if there are no changes 
in the transaction.

Fix: delete them in such cases.

The problem is that the read and write methods of the shared
memory transport (protocol) didn't react to asynchronous close
events, which could lead to a lock up as the client would wait
(until time out) for a server response that will never come.

The solution is to also wait for close events while waiting
for I/O from or to the server.

including modifications according to code review
+ backport of the fix for
  Bug 41932 funcs_1: is_collation_character_set_applicability path
                     too long for tar
  which was missing in 5.0 (just a renaming of two files)

      
When add an aliase name after NAME_CONST, the aliase name will be overwrite.
      
NAME_CONST will re-set the field's name only if there isn't an aliase in the
function fix-fields().
If there is an aliase, NAME_CONST doesn't re-set the field's name and keeps the old
name.

due to name_const substitution

Problem:
"In general, statements executed within a stored procedure
are written to the binary log using the same rules that
would apply were the statements to be executed in standalone
fashion. Some special care is taken when logging procedure
statements because statement execution within procedures
is not quite the same as in non-procedure context".

For example, each reference to a local variable in SP's
statements is replaced by NAME_CONST(var_name, var_value).
Queries like
"CREATE TABLE ... SELECT FUNC(local_var ..."
are logged as
"CREATE TABLE ... SELECT FUNC(NAME_CONST("local_var", var_value) ..."
that leads to differrent field names and
might result in "Incorrect column name" if var_value is long enough.

Fix: in 5.x we'll issue a warning in such a case.
In 6.0 we should get rid of NAME_CONST().

Note: this issue and change should be described in the documentation
("Binary Logging of Stored Programs").

Fine-tuning. Broke out comparison into method by
suggestion of Davi. Clarified comments. Reverting
test-case which I find too brittle; proper test
case in 5.1+.

(Pushing for Azundris)
      
We allow security-contexts with NULL users (for
system-threads and for unauthenticated users).
If a non-SUPER-user tried to KILL such a thread,
we tried to compare the user-fields to see whether
they owned that thread. Comparing against NULL was
not a good idea.
      
If KILLer does not have SUPER-privilege, we
specifically check whether both KILLer and KILLee
have a non-NULL user before testing for string-
equality. If either is NULL, we reject the KILL.

            
After the table is compressed by the myisampack utility,
opening the table by the server produces valgrind warnings.
      
This happens because when we try to read a record into the buffer
we alway assume that the remaining buffer to read is always equal 
to word size(4 or 8 or 2 bytes) we read. Sometimes we have 
remaining buffer size less than word size and trying to read the 
entire word size will end up in valgrind errors.
            
Fixed by reading byte by byte when we detect the remaining buffer 
size is less than the word size.

                    expired timeout on debx86-b in PB 

Moved the resource-intensive test case for bug #41486 into 
a separate test file to reduce execution time for mysql.test. 

                    produce incorrect results for ROUND() 

Added a workaround and a configure check to test whether 
isinf() is affected by the GCC bug #39228. 
       
Since no code in MySQL server is currently affected by that 
bug, the patch is actually a safeguard for possible future 
code modifications. No test cases or changelog entries are 
needed. 

When do 'insert delayed' operation, the time_zone info doesn't be keeped in the row info.
So when we do insert sometime later, time_zone didn't write into binlog.
This will cause wrong result for timestamp column in slave.

Our solution is that adding time_zone info with the delayed-row and
restoring time_zone from row-info when execute that row in the furture by another thread.
So we can write correct time_zone info into binlog and got correct result in slave.

   Details for Bug#43015 main.lock_multi: Weak code (sleeps etc.)
   -------------------------------------------------------------
   - The fix for bug 42003 already removed a lot of the weaknesses mentioned.
   - Tests showed that there are unfortunately no improvements of this tests
     in MySQL 5.1 which could be ported back to 5.0.
   - Remove a superfluous "--sleep 1" around line 195

   Details for Bug#43065 main.lock_multi: This test is too big if the disk is slow
   -------------------------------------------------------------------------------
   - move the subtests for the bugs 38499 and 36691 into separate scripts
   - runtime under excessive parallel I/O load after applying the fix
     lock_multi           [ pass ]          22887
     lock_multi_bug38499  [ pass ]         536926
     lock_multi_bug38691  [ pass ]         258498

When asking what database is selected, client expected
to *always* get an answer from the server.

We now handle failure more gracefully.

See comments in ticket for a discussion of what happens,
and how things interlock.

Don't compare string literals as it results in unspecified behavior.

functions
      
Unknown timezone specifications are properly rejected
by the server, but are copied into tz_storage before
rejection, and hence is retained until end of server 
life. With sufficiently large bogus timezone specs, 
it is easy to exhaust system memory.
      
Allocation of memory for a copy of the timezone
name is delayed until after verification of validity,
at the cost of a memcpy of the timezone info. This 
only happens once, future lookups will hit the cached
structure.

for bug #41486. Session max_allowed_packet is read-only
as of MySQL 5.1.31. In addition, the global variable
now has no effect on the current session.