Constant expressions in WHERE/HAVING/ON clauses aren't cached and evaluated
for each row. This causes slowdown of query execution especially if constant
UDF/SP function are used.
      
Now WHERE/HAVING/ON expressions are analyzed in the top-bottom direction with
help of the compile function. When analyzer meets a constant item it
sets a flag for the tree transformer to cache the item and doesn't allow tree
walker to go deeper. Thus, the topmost item of a constant expression if
cached. This is done after all other optimizations were applied to
WHERE/HAVING/ON expressions
      
A helper function called cache_const_exprs is added to the JOIN class.
It calls compile method with caching analyzer and transformer on WHERE,
HAVING, ON expressions if they're present.
The cache_const_expr_analyzer and cache_const_expr_transformer functions are
added to the Item class. The first one check if the item can be cached and
the second caches it if so.
A new Item_cache_datetime class is derived from the Item_cache class.
It caches both int and string values of the underlying item independently to
avoid DATETIME aware int-to-string conversion. Thus it completely relies on
the ability of the underlying item to correctly convert DATETIME value from
int to string and vice versa.

        ------------------------------------------------------------
        revno: 2617.81.1
        revision-id: tor.didriksen@sun.com-20090924061133-qo02zotz3yypmfpk
        parent: davi.arnaut@sun.com-20090923203724-tvz7x8dauzp686v7
        committer: Tor Didriksen <tor.didriksen@sun.com>
        branch nick: 6.0-codebase-bf-opt
        timestamp: Thu 2009-09-24 08:11:33 +0200
        message:
          Bug#47511 Segmentation fault during cleanup in sql_union (events_bugs.test)
          

since support for "%g" and "%f" has not been backported yet.

The semisync plugin library names on Unix like systems were prefixed with
'lib', which did not follow the conventions.

Fix the problem by removing the 'lib' prefix on Unix systems.

Conflicts:
  - sql/sql_insert.cc

    the 'shared-memory-base-name' was added to the [client] section of the my.cnf file.
    That option isn't supported by the mysqltest_embedded.

per-file comments:
  mysql-test/lib/My/ConfigFactory.pm

------------------------------------------------------------
revno: 3559
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: mysql-pe
timestamp: Fri 2009-08-28 15:23:16 -0300
message:
Break down a large and obnoxious "if" statement. Multiple "if" statements
makes it easy to understand and follow the code (specially in a debugger).

No commit message

----------------------------------------------------------------------
ChangeSet@1.2571, 2008-04-08 12:30:06+02:00, vvaintroub@wva. +122 -0
  Bug#32082 : definition of VOID in my_global.h conflicts with Windows
  SDK headers
  
  VOID macro is now removed. Its usage is replaced with void cast.
  In some cases, where cast does not make much sense (pthread_*, printf, 
  hash_delete, my_seek), cast is ommited.

-------------------------------------------------------------
revno: 2877
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 35164-6.0
timestamp: Wed 2008-10-15 19:53:18 -0300
message:
Bug#35164: Large number of invalid pthread_attr_setschedparam calls
Bug#37536: Thread scheduling causes performance degradation at low thread count
Bug#12702: Long queries take 100% of CPU and freeze other applications under Windows

The problem is that although having threads with different priorities
yields marginal improvements [1] in some platforms [2], relying on some
statically defined priorities (QUERY_PRIOR and WAIT_PRIOR) to play well
(or to work at all) with different scheduling practices and disciplines
is, at best, a shot in the dark as the meaning of priority values may
change depending on the scheduling policy set for the process.

Another problem is that increasing priorities can hurt other concurrent
(running on the same hardware) applications (such as AMP) by causing
starvation problems as MySQL threads will successively preempt lower
priority processes. This can be evidenced by Bug#12702.

The solution is to not change the threads priorities and rely on the
system scheduler to perform its job. This also enables a system admin
to increase or decrease the scheduling priority of the MySQL process,
if intended.

Furthermore, the internal wrappers and code for changing the priority
of threads is being removed as they are now unused and ancient.

1. Due to unintentional side effects. On Solaris this could artificially
help benchmarks as calling the priority changing syscall millions of
times is more beneficial than the actual setting of the priority.

2. Where it actually works. It has never worked on Linux as the default
scheduling policy SCHED_OTHER only accepts the static priority 0.

           root-directory not writable

Rather than use the -w test, attempt the chown and bail out if
it fails.

------------------------------------------------------------
revno: 2630.13.2
committer: Davi Arnaut <davi@sun.com>
branch nick: WL4284-6.0
timestamp: Thu 2008-07-03 18:26:51 -0300
message:
Remove unused USING_TRANSACTIONS macro which unnecessarily
cumbers the code. This macro is a historical leftover and
has no practical use since its unconditionally defined.

------------------------------------------------------------
revno: 2642
committer: davi@mysql.com/endora.local
timestamp: Fri 2008-05-16 01:29:09 -0300
message:
Fix for a valgrind warning due to a jump on a uninitialized
variable. The problem was that the sql profile preparation
function wasn't being called for all possible code paths
of query execution. The solution is to move the preparation
to the dispatch_command function and to explicitly call the
profile preparation function on bootstrap.

left join 

When creating a temporary TEXT/BLOB field from an Item in
Item::make_string_field(), the field's type was unconditionally
set to the one corresponding to the maximum length (i.e.
LONGTEXT/ LONGBLOB). This resulted in problems when exactly the
same TEXT/BLOB is type required in cases like CREATE ... SELECT
or creating internal temporary tables for joins. 

Fixed by calling a different constructor for Field_blob so that
an appropriate type is used depending on the Item's max_length
value.

Updated the result file for func_math.

------------------------------------------------------------
revno: 2627
committer: davi@mysql.com/endora.local
timestamp: Wed 2008-04-23 13:25:02 -0300
message:
Fix for a build failure on Windows due to ssize_t
not being declared.

This is the non-ndb part of the patch.

The return value of mysql_bin_log.write was ignored by most callers,
which may lead to inconsistent on master and slave if the transaction
was committed while the binlog was not correctly written. If
my_error() is call in mysql_bin_log.write, this could also lead to
assertion issue if my_ok() or my_error() is called after.

This fixed the problem by let the caller to check and handle the
return value of mysql_bin_log.write. This patch only adresses the
simple cases.

Original changeset:
------------------------------------------------------------
revno: 2626
committer: davi@mysql.com/endora.local
timestamp: Wed 2008-04-23 09:33:25 -0300
message:
Fix for main.ssl and main.ssl_compress test case failures under pool-of-threads.

The problem is that the SSL layer has a read buffer and might read
more data than requested by the VIO layer. The SSL layer empties the
socket buffer which causes the socket to not be signaled for IO if
the client is waiting for a command which is sitting in the read
buffer.

The solution is to retrieve from the transport layer the number of
bytes waiting in the read buffer. The data in the read buffer needs
to be processed before waiting for more data.

 inside a stored routine" from 6.0-codebase.

------------------------------------------------------------
revno: 2597.42.4
committer: davi@mysql.com/endora.local
timestamp: Tue 2008-04-15 17:29:42 -0300
message:
Bug#36004 mysql_stmt_prepare resets the list of warnings

Although the manual says that "the list of messages is reset
for each new statement that uses a table", the list of messages
is being unconditionally reset for prepare commands.

The solution is to enforce that the prepare command will only
reset the message list if the statement being prepared uses
a table or a warning is pushed.