In order to handle CHAR() fields, 8 bits were reserved for
the size of the CHAR field. However, instead of denoting the
number of characters in the field, field_length was used which
denotes the number of bytes in the field.
Since UTF-8 fields can have three bytes per character (and
has been extended to have four bytes per character in 6.0),
an extra two bits have been encoded in the field metadata
work for fields of type Field_string (i.e., CHAR fields).
Since the metadata word is filled, the extra bits have been
encoded in the upper 4 bits of the real type (the most
significant byte of the metadata word) by computing the
bitwise xor of the extra two bits. Since the upper 4 bits
of the real type always is 1111 for Field_string, this
means that for fields of length <256, the encoding is
identical to the encoding used in pre-5.1.26 servers, but
for lengths of 256 or more, an unrecognized type is formed,
causing an old slave (that does not handle lengths of 256
or more) to stop.
The crash appeared to be a result of allocating an instance of Discrete_interval
automatically that that was referred in out-of-declaration scope.
Fixed with correcting backing up and restoring scheme of
auto_inc_intervals_forced, introduced by bug#33029, by means of shallow copying;
added simulation code that forces executing those fixes of the former bug that
targeted at master-and-slave having incompatible bug#33029-prone versions.
In the patch for BUG#21842, the code for handling old rows events were
refactored. There were a bug in the refactored code (possibly introduced
after the patch for BUG#21842) that caused caused the refactored old events
to read a columns bitmap after image even though there is no such bitmap
for old events. As a result, the reading got out of sync, and started reading
invalid data.
This patch removes all trace of the after image column bitmap from the refactored
old events and removes functions that are no longer needed because they are empty.
