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.
* Fix clang warnings
* Remove vim tab guides
* initialize variables
* 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length
* Fix ISO C++17 does not allow 'register' storage class specifier for outdated bison
* chars are unsigned on ARM, having if (ival < 0) always false
* chars are unsigned by default on ARM and comparison with -1 if always true
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.
1. Make PredicateOperator::setOpType() function wide decimal aware.
2. Added support for wide decimal in jlf_subquery.cpp::getColumnValue()
used in scalar subqueries.
3. Fixed the column index used for fetching wide decimal values from a Row
when a wide decimal field is used in the order by clause.
simpleScalarFilterToParseTree() performs a dynamic allocation
of a ParseTree object, but this memory is never freed later.
We now keep track of this allocation and perform the delete
in ~CSEP/CSEP::unserialize() after the query finishes.
simpleScalarFilterToParseTree() performs a dynamic allocation
of a ParseTree object, but this memory is never freed later.
We now keep track of this allocation and perform the delete
in the JobList dtor after the query finishes.
MCOL-894 Add default values in Compare and CSEP ctors to activate UTF-8 sorting
properly.
MCOL-894 Unit tests to build a framework for a new parallel sorting.
MCOL-894 Finished with parallel workers invocation.
The implementation lacks final aggregation step.
MCOL-894 TupleAnnexStep's init and destructor are now parallel execution aware.
Implemented final merging step for parallel execution finalizeParallelOrderBy().
Templated unit test to use it with arbitrary number of rows, threads.
Reuse LimitedOrderBy in the final step
MCOL-894 Cleaned up finalizeParallelOrderBy.
MCOL-894 Add and propagate thread variable that controls a number of threads.
Optimized comparators used for sorting and add corresponding UTs.
Refactored TupleAnnexStep::finalizeParallelOrderByDistinct.
Parallel sorting methods now preallocates memory in batches.
MCOL-894 Fixed comparator for StringCompare.
2. Fallback to using sql_select_limit system variable value if an explicit limit is not supplied.
3. Remove checks that did not allow (2^64 - 1) as a valid limit value.
pDictionaryScan won't work for BLOB/TEXT since it requires searching the
data file and rebuilding the token from matches. The tokens can't be
rebuild correctly due the bits in the token used for block counts. This
patch forces the use of pDictionaryStep instead for WHERE conditions.
In addition this patch adds support for TEXT/BLOB in various parts of
the job step processing. This fixes things like error 202 during an
UPDATE with a join condition on TEXT/BLOB columns.
During subquery processing it is possible to have an empty Having
clause. When this happens various tree elements are deleted but the
pointers to those tree elements are not set to NULL. So later on in
processing ExeMgr can crash.
