into  janus.mylan:/usr/home/serg/Abk/mysql-5.1

into  trift2.:/MySQL/M51/mysql-5.1

into  mysql.com:/home/svoj/devel/bk/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/bk/mysql-5.0-engines

into  mockturtle.local:/home/dlenev/src/mysql-4.1-merge

into  mockturtle.local:/home/dlenev/src/mysql-5.0-merge

into  mockturtle.local:/home/dlenev/src/mysql-5.1-bg25966

into  mockturtle.local:/home/dlenev/src/mysql-5.0-bg25966-2

TABLE ... WRITE".

Memory and CPU hogging occured when connection which had to wait for table
lock was serviced by thread which previously serviced connection that was
killed (note that connections can reuse threads if thread cache is enabled).
One possible scenario which exposed this problem was when thread which
provided binlog dump to replication slave was implicitly/automatically
killed when the same slave reconnected and started pulling data through
different thread/connection.
The problem also occured when one killed particular query in connection
(using KILL QUERY) and later this connection had to wait for some table
lock.

This problem was caused by the fact that thread-specific mysys_var::abort
variable, which indicates that waiting operations on mysys layer should
be aborted (this includes waiting for table locks), was set by kill
operation but was never reset back. So this value was "inherited" by the
following statements or even other connections (which reused the same
physical thread). Such discrepancy between this variable and THD::killed
flag broke logic on SQL-layer and caused CPU and memory hogging.

This patch tries to fix this problem by properly resetting this member.

There is no test-case associated with this patch since it is hard to test
for memory/CPU hogging conditions in our test-suite.

TABLE ... WRITE".

CPU hogging occured when connection which had to wait for table lock was
serviced by thread which previously serviced connection that was killed
(note that connections can reuse threads if thread cache is enabled).
One possible scenario which exposed this problem was when thread which
provided binlog dump to replication slave was implicitly/automatically
killed when the same slave reconnected and started pulling data through
different thread/connection.
In 5.* versions memory hogging was added to CPU hogging. Moreover in
those versions the problem also occured when one killed particular query
in connection (using KILL QUERY) and later this connection had to wait for
some table lock.

This problem was caused by the fact that thread-specific mysys_var::abort
variable, which indicates that waiting operations on mysys layer should
be aborted (this includes waiting for table locks), was set by kill
operation but was never reset back. So this value was "inherited" by the
following statements or even other connections (which reused the same
physical thread). Such discrepancy between this variable and THD::killed
flag broke logic on SQL-layer and caused CPU and memory hogging.

This patch tries to fix this problem by properly resetting this member.

There is no test-case associated with this patch since it is hard to test
for memory/CPU hogging conditions in our test-suite.

into  mockturtle.local:/home/dlenev/src/mysql-5.1-bg25966

into  mysql.com:/home/kent/bk/tmp/mysql-5.1-build

into  mysql.com:/home/kent/bk/tmp/mysql-5.0-build

into  mysql.com:/home/kent/bk/tmp/mysql-4.1-build

  Updated to version 0.6 of the text

into  mysql.com:/home/kent/bk/tmp/mysql-5.1-build

into  mysql.com:/home/kent/bk/tmp/mysql-5.1-build

into  mysql.com:/home/kent/bk/tmp/mysql-5.0-build

into  mysql.com:/home/kent/bk/tmp/mysql-5.0-build

into  mysql.com:/home/kent/bk/tmp/mysql-4.1-build

into  mysql.com:/home/kent/bk/tmp/mysql-4.1-build

  Added test for sched_yield() possibly in -lposix4 on Solaris

into  blade08.mysql.com:/data0/istruewing/autopush/mysql-5.1-bug25460

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-5.1-engines

into  blade08.mysql.com:/data0/istruewing/autopush/mysql-5.1-bug25460

The previous two patches for this bug worked together so that
no permanent table was memory mapped. The first patch tried to
avoid mapping while a table is in use. It allowed mapping only
if there was exactly one lock on the table, assuming that the
calling thread owned it. During mi_open(), a different call to
memory mapping was coded, which did not have this limitation.

The second patch tried to remove the code duplication and just
called mi_extra() from mi_open() an thus inherited the limitation.
But on open, a thread does not have a lock on the table...

A possible solution would be to check for zero or one lock.
But since I learned that it is safe to memory map a file while
normal file I/O is done on it, I removed the restriction altogether
and allow to memory map while a table is in use.

No test case. I do not see a chance to verify with the test suite
which kind of I/O is used on a table.

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-5.0-engines

            differences in tables
Certain merge tables were wrongly reported as having incorrect definition:
- Some fields that are 1 byte long (e.g. TINYINT, CHAR(1)), might
  be internally casted (in certain cases) to a different type on a
  storage engine layer. (affects 4.1 and up)
- If tables in a merge (and a MERGE table itself) had short VARCHAR column (less
  than 4 bytes) and at least one (but not all) tables were ALTER'ed (even to an
  identical table: ALTER TABLE xxx ENGINE=yyy), table definitions went ouf of
  sync. (affects 4.1 only)

This is fixed by relaxing a check for underlying conformance and setting
field type to FIELD_TYPE_STRING in case varchar is shorter than 4
when a table is created.

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/BUG26881/mysql-4.1-engines

into  mysql.com:/home/kent/bk/tmp/mysql-5.0-build

into  mysql.com:/home/kent/bk/tmp/mysql-5.1-build

into  mysql.com:/home/kent/bk/tmp/mysql-5.0-build