For some reason, the tests of the MemorySanitizer build on 10.5 failed
with both clang 13 and clang 14 with SIGSEGV. On 10.6 where it worked
better, some more places to work around were identified.
MDEV-24841 Build error with MSAN use-of-uninitialized-value in comp_err
The MemorySanitizer implementation in clang includes some built-in
instrumentation (interceptors) for GNU libc. In GNU libc 2.33, the
interface to the stat() family of functions was changed. Until the
MemorySanitizer interceptors are adjusted, any MSAN code builds
will act as if that the stat() family of functions failed to initialize
the struct stat.
In commit 83212632e4b5f824edc8327be750feed32a96054
the trx_rseg_latch was instrumented for performance_schema,
but some acqusitions of rd_lock() were not adjusted.
Thus, the build would fail on platforms where a futex-based
rw-lock is not available (SUX_LOCK_GENERIC) unless the code
was built with cmake -DPLUGIN_PERFSCHEMA=NO.
MDEV-27169 Change default values of Spider plugin variables to default values of table variables
Some Spider table options introduces an unnecessary complication to
Spider settings. For example, the default value of the plugin variable
spider_auto_increment_mode is -1 (use table value) and the default
table option value is 0 (normal mode). Thus, the virtual default value
of the variable is 0. This kind of indirection is confusing.
In order to delete such confusing table options in a future release,
we first change the default values of some Spider plugin variables
from -1 (use table value) to the corresponding default table values.
The default table values are defined in spider_set_connect_info_default().
At the same time, we also deprecate the option value -1 (use table value).
Deprecate the plugin variable spider_use_handler and the corresponding
table parameters "uhd" and "use_handler".
Passing a Handler statement to data nodes, without converting it to
SQL sometimes, might improve the performance, while this introduces
some complication to the implementation.
In the first place, only a few people use Handler statements and the
performance gain seems not to be very significant. Further, setting
spider_use_handler > 0 disables the GROUP BY handler. So, we decided
to deprecate the variable.
