bug #49251 (deadlock/crash with concurrent truncate table and index
statistics calculation) by backporting a solution from #54678 fixed
for 5.1 plugin and 5.5.

            within query

The server could crash after materializing a derived table
which requires a temporary table for grouping.

When destroying the temporary table used to execute a query for
a derived table, JOIN::destroy() did not clean up Item_fields
pointing to fields in the temporary table. This led to
dereferencing a dangling pointer when printing out the items
tree later in the outer SELECT.

The solution is an addendum to the patch for bug37362: in
addition to cleaning up items in tmp_all_fields3, do the same
for items in tmp_all_fields1, since now we have an example
where this is necessary.

  KILL_BAD_DATA is returned

Two problems discovered with the LEAST()/GREATEST() 
functions:
1. The check for a null value should happen even 
after the second call to val_str() in the args. This is
important because two subsequent calls to the same
Item::val_str() may yield different results.
Fixed by checking for NULL value before dereferencing
the string result.

2. While looping over the arguments and evaluating them 
the loop should stop if there was an error evaluating so far
or the statement was killed. Fixed by checking for error
and bailing out.

        'CREATE TABLE IF NOT EXISTS ... SELECT' behaviour
BUG#55474, BUG#55499, BUG#55598, BUG#55616 and BUG#55777 are fixed
in this patch too.

This is the 5.1 part.
It implements:
- if the table exists, binlog two events: CREATE TABLE IF NOT EXISTS
  and INSERT ... SELECT

- Insert nothing and binlog nothing on master if the existing object
  is a view. It only generates a warning that table already exists.

An user assignment variable expression that's 
evaluated in a logical expression context 
(Item::val_bool()) can be pre-calculated in a 
temporary table for GROUP BY.
However when the expression value is used after the
temp table creation it was re-evaluated instead of
being read from the temp table due to a missing 
val_bool_result() method.
Fixed by implementing the method.

The server was not checking for errors generated during
the execution of Item::val_xxx() methods when copying
data to the group, order, or distinct temp table's row.
Fixed by extending the copy_funcs() to return an error
code and by checking for that error code on the places
copy_funcs() is called. 
Test case added.

variable assignments

The assert() that is firing is checking if expressions that can't be
null return a NULL when evaluated.
MAKEDATE() function can return NULL if the second argument is 
less then or equal to 0. Thus its nullability depends not only on 
the nullability of its arguments but also on their values.
Fixed by (overoptimistically) setting MAKEDATE() to be nullable 
despite the nullability of its arguments.
Test added.
Had to update one test result to reflect the metadata change.

feature

The test for bug no 50939 was put in range.test which isn't such a good idea
since it requires partitioning. Fixed by moving the test case to
partitioning_range.test.

Updated the README file.

           INSERT IGNORE ... SELECT ... UNION SELECT ...

This assert was triggered by INSERT IGNORE ... SELECT. The assert checks that a
statement either sends OK or an error to the client. If the bug was triggered
on release builds, it caused OK to be sent to the client instead of the correct
error message (in this case ER_FIELD_SPECIFIED_TWICE).

The reason the assert was triggered, was that lex->no_error was set to TRUE
during JOIN::optimize() because of IGNORE. This causes all errors to be ignored.
However, not all errors can be ignored. Some, such as ER_FIELD_SPECIFIED_TWICE
will cause the INSERT to fail no matter what. But since lex->no_error was set,
the critical errors were ignored, the INSERT failed and neither OK nor the
error message was sent to the client.

This patch fixes the problem by temporarily turning off lex->no_error in
places where errors cannot be ignored during processing of INSERT ... SELECT.

Test case added to insert.test.

The CONVERT_TZ function crashes the server when the
timezone argument is an empty SET field value.

1) The CONVERT_TZ may find a timezone string in the
   tz_names hash.
2) A string representation of the empty SET is a
   String of zero length with the NULL pointer.
3) If the key argument length is zero, hash functions
   do comparison using the length of the record being
   compared against.

I.e. a zero-length String buffer is an invalid
argument for hash search functions, and if String
points to NULL buffer, hashcmp() fails with SEGV
accessing that memory.

The my_tz_find function has been modified to
treat empty Strings as invalid timezone values
to skip unnecessary hash search.

read_rnd_buffer_size

Applied the updated description from Paul's patch.

Undo workaround as fix is being merged in

failures on sparc64.

file .\item_subselect.cc, line 836

IN quantified predicates are never executed directly. They are rather wrapped
inside nodes called IN Optimizers (Item_in_optimizer) which take care of the
execution. However, this is not done during query preparation. Unfortunately
the LIKE predicate pre-evaluates constant right-hand side arguments even
during name resolution. Likely this is meant as an optimization.

Fixed by not pre-evaluating LIKE arguments in view prepare mode.

Handle overflow when reading value from SELECT MAX(C) FROM T;

Call ha_innobase::info() after initializing the autoinc value
in ha_innobase::open().

Fix for both the builtin and plugin.

rb://402

The bug is due to a double delete of a BLOB, once via:

    rollback -> btr_cur_pessimistic_delete()

and the second time via purge.

The bug is in row_upd_clust_rec_by_insert(). There we relinquish ownership
of the non-updated BLOB columns in btr_cur_mark_extern_inherited_fields()
before building the row entry that will be inserted and whose contents will
be logged in the UNDO log. However, we don't set the BLOB column later to
INHERITED so that a possible rollback will not free the original row's
non-updated BLOB entries. This is because the condition that checks for
that is in :

	if (node->upd_ext) {}.

node->upd_ext is non-NULL only if a BLOB column was updated and that column
is part of some key ordering (see row_upd_replace()). This results in the
non-update BLOB columns being deleted during a rollback and subsequently by
purge again.

rb://413

Reverted the ulong->uint diff
Re-applied the first diff.
The original commit message follows:

enum plugin system variables are ulong internally, not int.
On systems where long is not the same as an int it causes
problems. 
Fixed by correct typecasting. Removed the test from the 
experimental list.

rb://399 approved by Sunny Bains

foreign keys at once

rb://391 approved by Heikki
Z

Follow-up patch: added test cases for -0 and while

The enum system variables were handled inconsistently 
as ints, unsigned int and unsigned long on various places.
This caused problems on platforms on which 
sizeof(int) != sizeof(long).
Fixed by homogenizing the type of the enum variables
to unsigned int, since it's size compatible with the C enum
type. 
Removed the test from the experimental list.

if() treated any non-numeric string as false
Fixed to treat those as true instead
Added some test cases
Fixed missing $ in variable name in include/mix2.inc

Post fix