As is suggested in issue #15257, the function preimage is a general
solution to the optimization problem with predicates containing the
date and datetime converters. This commit implements the idea by
adding the new methods, hasInformationAboutPreimage and getPreimage,
to IFunction/IFunctionBase, and having the specific convert functions
define their own preimage. Moreover, we added a new pass in the
TreeOptimizer and a new AST visitor for in-place rewriting the AST
with the converters' preimage.
Specifically, the optimization is applied to toYear and toYYYYMM.
It was quite some time ago since it was replaced by plan level
optimizations:
- query_plan_remove_redundant_sorting
- query_plan_remove_redundant_distinct
The date converters, such as toYear, are widely used in the where
clauses of the SQL queries, however, these conversions are often
expensive due to the complexity of the calendar system.
The function preimage is found an optimization for the predicates
with the converters. Given a predicate, toYear(c) = y, we could
convert it to its equivalent form: c >= b AND c <= e, where b is
"y-01-01" and e is "y-12-31". The similar transformation applies
to other comparisons (<>, <, >, <=, <=).
This commit implemented the above transformation at the AST level
by adding a new pass in the TreeOptimizer and a new AST visitor
for in-place replacing the predicates of toYear with the converted
ones.
* save format string for NetException
* format exceptions
* format exceptions 2
* format exceptions 3
* format exceptions 4
* format exceptions 5
* format exceptions 6
* fix
* format exceptions 7
* format exceptions 8
* Update MergeTreeIndexGin.cpp
* Update AggregateFunctionMap.cpp
* Update AggregateFunctionMap.cpp
* fix
When I tried to add cool new clang-tidy 14 warnings, I noticed that the
current clang-tidy settings already produce a ton of warnings. This
commit addresses many of these. Almost all of them were non-critical,
i.e. C vs. C++ style casts.
