This patch improves handling of NULLs in textual fields in ColumnStore.
Previously empty strings were considered NULLs and it could be a problem
if data scheme allows for empty strings. It was also one of major
reasons of behavior difference between ColumnStore and other engines in
MariaDB family.
Also, this patch fixes some other bugs and incorrect behavior, for
example, incorrect comparison for "column <= ''" which evaluates to
constant True for all purposes before this patch.
* toCppCode for ParseTree and TreeNode
* generated tree is compiling
* Put tree constructors into tests
* Minor fixes
* Fixed parse + some constructors
* Fixed includes, removed debug and old data
* Hopefully fix clang errors
* Forgot an override
* More overrides
Part 1:
As part of MCOL-3776 to address synchronization issue while accessing
the fTimeZone member of the Func class, mutex locks were added to the
accessor and mutator methods. However, this slows down processing
of TIMESTAMP columns in PrimProc significantly as all threads across
all concurrently running queries would serialize on the mutex. This
is because PrimProc only has a single global object for the functor
class (class derived from Func in utils/funcexp/functor.h) for a given
function name. To fix this problem:
(1) We remove the fTimeZone as a member of the Func derived classes
(hence removing the mutexes) and instead use the fOperationType
member of the FunctionColumn class to propagate the timezone values
down to the individual functor processing functions such as
FunctionColumn::getStrVal(), FunctionColumn::getIntVal(), etc.
(2) To achieve (1), a timezone member is added to the
execplan::CalpontSystemCatalog::ColType class.
Part 2:
Several functors in the Funcexp code call dataconvert::gmtSecToMySQLTime()
and dataconvert::mySQLTimeToGmtSec() functions for conversion between seconds
since unix epoch and broken-down representation. These functions in turn call
the C library function localtime_r() which currently has a known bug of holding
a global lock via a call to __tz_convert. This significantly reduces performance
in multi-threaded applications where multiple threads concurrently call
localtime_r(). More details on the bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=16145
This bug in localtime_r() caused processing of the Functors in PrimProc to
slowdown significantly since a query execution causes Functors code to be
processed in a multi-threaded manner.
As a fix, we remove the calls to localtime_r() from gmtSecToMySQLTime()
and mySQLTimeToGmtSec() by performing the timezone-to-offset conversion
(done in dataconvert::timeZoneToOffset()) during the execution plan
creation in the plugin. Note that localtime_r() is only called when the
time_zone system variable is set to "SYSTEM".
This fix also required changing the timezone type from a std::string to
a long across the system.
When an outer query filter accesses an subquery column that contains an aggregate or a window function, certain optimizations can't be performed. We had been looking at the surface of the returned column. We now iterate into any functions or operations looking for aggregates and window functions.
In addition, a regression in a WHERE clause with a WF field
as the LHS and an addition operation on two WF fields on the RHS
is also fixed. The issue was SimpleColumn::getDecimalVal() was
setting precision = 19, with the value of one of the operands of the
addition operation being set in VDecimal::value instead of
VDecimal::s128Value. addSubtractExecute() in mcs_decimal.cpp makes the
assumption that if precision > 18 and precision <= 38, we need to
fetch the wide s128Value, not the narrow value field. So we are
fixing the precision set in SimpleColumn::getDecimalVal().
Removed uint128 from joblist/lbidlist.*
Another toString() method for wide-decimal that is EMPTY/NULL aware
Unified decimal processing in WF functions
Fixed a potential issue in EqualCompData::operator() for
wide-decimal processing
Fixed some signedness warnings
WF::percentile runtime threw an exception b/c of wrong DT deduced from its argument
Replaced literals with constants
Tought WF_sum_avg::checkSumLimit to use refs instead of values
