This was noticed wben running "mtr --valgrind main.precedence"
The problem was that Item_func_like::escape could be left unitialized
when used with views combined with UNIONS like in:
create or replace view v1 as select 2 LIKE 1 ESCAPE 3 IN (SELECT 0 UNION SELECT 1), 2 LIKE 1 ESCAPE (3 IN (SELECT 0 UNION SELECT 1)), (2 LIKE 1 ESCAPE 3) IN (SELECT 0 UNION SELECT 1);
The above query causes in fix_escape_item()
escape_item->const_during_execution() to be true
and
escape_item->const_item() to be false
in which case 'escape' is never calculated.
The fix is to make the main logic of fix_escape_item() out to a
separate function and call that function once in Item.
Other things:
- Reorganized fields in Item_func_like class to make it more compact
fix printing precedence for BETWEEN, LIKE/ESCAPE, REGEXP, IN
don't use precedence for printing CASE/WHEN/THEN/ELSE/END
fix parsing precedence of BETWEEN, LIKE/ESCAPE, REGEXP, IN
support predicate arguments for IN, BETWEEN, SOUNDS LIKE, LIKE/ESCAPE,
REGEXP
use %nonassoc for unary operators
fix parsing of IS TRUE/FALSE/UNKNOWN/NULL
remove parser_precedence test as superseded by the precedence test
IFNULL(inet6_not_null_expr, 'foo') erroneously set its nullability to NOT NULL.
Fix:
- Moving the line "maybe_null= args[1]->maybe_null" before the call
of fix_length_and_dec2(), so the call of Type_handler method
Item_hybrid_func_fix_attributes() can reset it when desired.
- Fixing Type_handler_inet6::Item_hybrid_func_fix_attributes()
to ignore args[0] when detecting nullability of IFNULL().
Final added to:
- All reasonable classes inhereted from Field
- All classes inhereted from Protocol
- Almost all Handler classes
- Some important Item classes
The stripped size of mariadbd is just 4K smaller, but several object files
showed notable improvements in common execution paths.
- Checked field.o and item_sum.o
Other things:
- Added 'override' to a few class functions touched by this patch.
- Removed 'virtual' from a new class functions that had/got 'override'
- Changed Protocol_discard to inherit from Protocol instad of Protocol_text
when Item::print() is called with the QT_PARSABLE flag, WHERE i NOT IN
(SELECT ...) gets printed as WHERE !i IN (SELECT ...) instead of WHERE
!(i in (SELECT ...)) because Item_in_optimizer returns DEFAULT_PRECEDENCE.
it should return the precedence of the inner operation.
with condition_pushdown_from_having
This bug could manifest itself for queries with GROUP BY and HAVING clauses
when the HAVING clause was a conjunctive condition that depended
exclusively on grouping fields and at least one conjunct contained an
equality of the form fld=sq where fld is a grouping field and sq is a
constant subquery.
In this case the optimizer tries to perform a pushdown of the HAVING
condition into WHERE. To construct the pushable condition the optimizer
first transforms all multiple equalities in HAVING into simple equalities.
This has to be done for a proper processing of the pushed conditions
in WHERE. The multiple equalities at all AND/OR levels must be converted
to simple equalities because any multiple equality may refer to a multiple
equality at the upper level.
Before this patch the conversion was performed like this:
multiple_equality(x,f1,...,fn) => x=f1 and ... and x=fn.
When an equality item for x=fi was constructed both the items for x and fi
were cloned. If x happened to be a constant subquery that could not be
cloned the conversion failed. If the conversions of multiple equalities
previously performed had succeeded then the whole condition became in an
inconsistent state that could cause different failures.
The solution provided by the patch is:
1. to use a different conversion rule if x is a constant
multiple_equality(x,f1,...,fn) => f1=x and f2=f1 and ... and fn=f1
2. not to clone x if it's a constant.
Such conversions cannot fail and besides the result of the conversion
preserves the equivalence of f1,...,fn that can be used for other
optimizations.
This patch also made sure that expensive predicates are not pushed from
HAVING to WHERE.
item_cmpfunc.h includes pcre2.h, so with the bundled pcre2
it has to be built before anything that includes pcre2.h .
And item_cmpfunc.h is indirectly included everywhere,
also in many plugins.
Somehow Ninja and Makefiles generators can still deduce the
correct build dependencies, but Visual Studio generator cannot.
Two changes:
* move pcre2.h from item_cmpfunc.h to item_cmpfunc.cc
* create an explicit dependency on pcre2 for the server
fix bug for spider where using "not like" (#890)
test case:
t1 is a spider engine table;
CREATE TABLE `t1` (
`id` int(11) NOT NULL DEFAULT '0',
`name` char(64) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=SPIDER
query: "select * from t1 where name not like 'x%' " would dispatch "select xxx name name like 'x%' " to remote mysqld, is wrong
This change takes into account a column's GENERATED ALWAYS AS
expression dependcy on sql_mode's PAD_CHAR_TO_FULL_LENGTH and
NO_UNSIGNED_SUBTRACTION flags.
Indexed virtual columns as well as persistent generated columns are
now not allowed to have such dependencies to avoid inconsistent data
or index files on sql_mode changes.
So an error is now returned in cases like this:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v VARCHAR(5) AS (a) PERSISTENT -- CHAR->VARCHAR or CHAR->TEXT = ERROR
);
Functions RPAD() and RTRIM() can now remove dependency on
PAD_CHAR_TO_FULL_LENGTH. So this can be used instead:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v VARCHAR(5) AS (RTRIM(a)) PERSISTENT
);
Note, unlike CHAR->VARCHAR and CHAR->TEXT this still works,
not RPAD(a) is needed:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v CHAR(5) AS (a) PERSISTENT -- CHAR->CHAR is OK
);
More sql_mode flags may affect values of generated columns.
They will be addressed separately.
See comments in sql_mode.h for implementation details.
This patch introduces the optimization that allows range optimizer to
consider index range scans that are built employing NOT NULL predicates
inferred from WHERE conditions and ON expressions.
The patch adds a new optimizer switch not_null_range_scan.
