(temporary) TABLE, crash

Problem: if one has an open "HANDLER t1", further "TRUNCATE t1" 
doesn't close the handler and leaves handler table hash in an 
inconsistent state, that may lead to a server crash.

Fix: TRUNCATE should implicitly close all open handlers.

Doc. request: the fact should be described in the manual accordingly.

view manipulations
      
The bespoke flag was not properly reset after last call to 
fill_record. Fixed by resetting in caller mysql_update.

view that has Group By
      
Table access rights checking function check_grant() assumed
that no view is opened when it's called.
This is not true with nested views where the inner view
needs materialization. In this case the view is already 
materialized when check_grant() is called for it.
This caused check_grant() to not look for table level
grants on the materialized view table.
Fixed by checking if a view is already materialized and if 
it is check table level grants using the original table name
(not the ones of the materialized temp table).

Bug#45243: crash on win in sql thread clear_tables_to_lock() -> free()
Bug#45242: crash on win in mysql_close() -> free()
Bug#45238: rpl_slave_skip, rpl_change_master failed (lost connection) for STOP SLAVE
Bug#46030: rpl_truncate_3innodb causes server crash on windows
Bug#46014: rpl_stm_reset_slave crashes the server sporadically in pb2

When killing a user session on the server, it's necessary to
interrupt (notify) the thread associated with the session that
the connection is being killed so that the thread is woken up
if waiting for I/O. On a few platforms (Mac, Windows and HP-UX)
where the SIGNAL_WITH_VIO_CLOSE flag is defined, this interruption
procedure is to asynchronously close the underlying socket of
the connection.

In order to enable this schema, each connection serving thread
registers its VIO (I/O interface) so that other threads can
access it and close the connection. But only the owner thread of
the VIO might delete it as to guarantee that other threads won't
see freed memory (the thread unregisters the VIO before deleting
it). A side note: closing the socket introduces a harmless race
that might cause a thread attempt to read from a closed socket,
but this is deemed acceptable.

The problem is that this infrastructure was meant to only be used
by server threads, but the slave I/O thread was registering the
VIO of a mysql handle (a client API structure that represents a
connection to another server instance) as a active connection of
the thread. But under some circumstances such as network failures,
the client API might destroy the VIO associated with a handle at
will, yet the VIO wouldn't be properly unregistered. This could
lead to accesses to freed data if a thread attempted to kill a
slave I/O thread whose connection was already broken.

There was a attempt to work around this by checking whether
the socket was being interrupted, but this hack didn't work as
intended due to the aforementioned race -- attempting to read
from the socket would yield a "bad file descriptor" error.

The solution is to add a hook to the client API that is called
from the client code before the VIO of a handle is deleted.
This hook allows the slave I/O thread to detach the active vio
so it does not point to freed memory.

on SHOW CREATE TRIGGER + MERGE table

Problem: SHOW CREATE TRIGGER erroneously relies on fact
that we have the only underlying table for a trigger
(wrong for merge tables).

Fix: remove erroneous assert().

There is an inconsistency with DROP DATABASE|TABLE|EVENT IF EXISTS and
CREATE DATABASE|TABLE|EVENT IF NOT EXISTS. DROP IF EXISTS statements are
binlogged even if either the DB, TABLE or EVENT does not exist. In
contrast, Only the CREATE EVENT IF NOT EXISTS is binlogged when the EVENT
exists.  

This patch fixes the following cases for all the replication formats:
CREATE DATABASE IF NOT EXISTS.
CREATE TABLE IF NOT EXISTS,
CREATE TABLE IF NOT EXISTS ... LIKE,
CREAET TABLE IF NOT EXISTS ... SELECT.

"CREATE TABLE TRANSACTIONAL PAGE_CHECKSUM ROW_FORMAT=PAGE accepted, 
does nothing".

Put back stubs for members of structures that are shared between
sql/ and pluggable storage engines. to not break ABI unnecessarily.
To be NULL-merged into 5.4, where we do break the ABI already.

PAGE_CHECKSUM ROW_FORMAT=PAGE accepted, does nothing"
Remove unused code that would lead to warnings when compiling
sql_yacc.yy.

        
Replication SQL thread does not set database default charset to 
thd->variables.collation_database properly, when executing LOAD DATA binlog.
This bug can be repeated by using "LOAD DATA" command in STATEMENT mode.
        
This patch adds code to find the default character set of the current database 
then assign it to thd->db_charset when slave server begins to execute a relay log.
The test of this bug is added into rpl_loaddata_charset.test 

The problem is that the lexer could inadvertently skip over the
end of a query being parsed if it encountered a malformed multibyte
character. A specially crated query string could cause the lexer
to jump up to six bytes past the end of the query buffer. Another
problem was that the laxer could use unfiltered user input as
a signed array index for the parser maps (having upper and lower
bounds 0 and 256 respectively).

The solution is to ensure that the lexer only skips over well-formed
multibyte characters and that the index value of the parser maps
is always a unsigned value.

Problem 1:
When the 'Using index' optimization is used, the optimizer may still - after
cost-based optimization - decide to use another index in order to avoid using
a temporary table. But when this happens, the flag to the storage engine to 
read index only (not table) was still set. Fixed by resetting the flag in the 
storage engine and TABLE structure in the above scenario, unless the new index
allows for the same optimization.
Problem 2:
When a 'ref' access method was employed by cost-based optimizer, (when the column
is non-NULLable), it was assumed that it needed no initialization if 'quick' access
methods (since they are based on range scan). When ORDER BY optimization overrides 
the decision, however, it expects to have this initialized and hence crashes. 
Fixed in 5.1 (was fixed in 6.0 already) by initializing 'quick' even when there's 
'ref' access. 

- Remove offensive quotes.

when partition is reoganized.

Problem was that table->timestamp_field_type was not changed
before copying rows between partitions.

fixed by setting it to TIMESTAMP_NO_AUTO_SET as the first thing
in fast_alter_partition_table, so that all if-branches is covered.

                    column on partitioned table
      
      
An assertion 'ASSERT_COULUMN_MARKED_FOR_READ' is failed if the query 
is executed with index containing double column on partitioned table.
The problem is that assertion expects all the fields which are read,
to be in the read_set.
      
In this query only the field 'a' is in the readset as the tables in
the query are joined by the field 'a' and so the assertion fails 
expecting other field 'b'.
      
Since the function cmp() is just comparison of two parameters passed, 
the assertion is not required.
      
Fixed by removing the assertion in the double fields comparision
function and also fixed the index initialization to do ordered
index scan with RW LOCK which ensures all the fields from a key are in
the read_set.
 

Note: this bug is not reproducible with other datatypes because the
      assertion doesn't exist in comparision function for other 
      datatypes.