During the 10.5->10.6 merge please use the 10.6 code on conflicts.
This is the 10.5 version of the patch (a backport of the 10.6 version).
Unlike 10.6 version, it makes changes in plugin/type_inet/sql_type_inet.*
rather than in sql/sql_type_fixedbin.h
Item_bool_rowready_func2, Item_func_between, Item_func_in
did not check if a not-NULL argument of an arbitrary data type
can produce a NULL value on conversion to INET6.
This caused a crash on DBUG_ASSERT() in conversion failures,
because the function returned SQL NULL for something that
has Item::maybe_null() equal to false.
Adding setting NULL-ability in such cases.
Details:
- Removing the code in Item_func::setup_args_and_comparator()
performing character set aggregation with optional narrowing.
This aggregation is done inside Arg_comparator::set_cmp_func_string().
So this code was redundant
- Removing Item_func::setup_args_and_comparator() as it git simplified to
just to two lines:
convert_const_compared_to_int_field(thd);
return cmp->set_cmp_func(thd, this, &args[0], &args[1], true);
Using these lines directly in:
- Item_bool_rowready_func2::fix_length_and_dec()
- Item_func_nullif::fix_length_and_dec()
- Adding a new virtual method:
- Type_handler::Item_bool_rowready_func2_fix_length_and_dec().
- Adding tests detecting if the data type conversion can return SQL NULL into
the following methods of Type_handler_inet6:
- Item_bool_rowready_func2_fix_length_and_dec
- Item_func_between_fix_length_and_dec
- Item_func_in_fix_comparator_compatible_types
The crash happened with an indexed virtual column whose
value is evaluated using a function that has a different meaning
in sql_mode='' vs sql_mode=ORACLE:
- DECODE()
- LTRIM()
- RTRIM()
- LPAD()
- RPAD()
- REPLACE()
- SUBSTR()
For example:
CREATE TABLE t1 (
b VARCHAR(1),
g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL,
KEY g(g)
);
So far we had replacement XXX_ORACLE() functions for all mentioned function,
e.g. SUBSTR_ORACLE() for SUBSTR(). So it was possible to correctly re-parse
SUBSTR_ORACLE() even in sql_mode=''.
But it was not possible to re-parse the MariaDB version of SUBSTR()
after switching to sql_mode=ORACLE. It was erroneously mis-interpreted
as SUBSTR_ORACLE().
As a result, this combination worked fine:
SET sql_mode=ORACLE;
CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...;
INSERT ...
FLUSH TABLES;
SET sql_mode='';
INSERT ...
But the other way around it crashed:
SET sql_mode='';
CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...;
INSERT ...
FLUSH TABLES;
SET sql_mode=ORACLE;
INSERT ...
At CREATE time, SUBSTR was instantiated as Item_func_substr and printed
in the FRM file as substr(). At re-open time with sql_mode=ORACLE, "substr()"
was erroneously instantiated as Item_func_substr_oracle.
Fix:
The fix proposes a symmetric solution. It provides a way to re-parse reliably
all sql_mode dependent functions to their original CREATE TABLE time meaning,
no matter what the open-time sql_mode is.
We take advantage of the same idea we previously used to resolve sql_mode
dependent data types.
Now all sql_mode dependent functions are printed by SHOW using a schema
qualifier when the current sql_mode differs from the function sql_mode:
SET sql_mode='';
CREATE TABLE t1 ... SUBSTR(a,b,c) ..;
SET sql_mode=ORACLE;
SHOW CREATE TABLE t1; -> mariadb_schema.substr(a,b,c)
SET sql_mode=ORACLE;
CREATE TABLE t2 ... SUBSTR(a,b,c) ..;
SET sql_mode='';
SHOW CREATE TABLE t1; -> oracle_schema.substr(a,b,c)
Old replacement names like substr_oracle() are still understood for
backward compatibility and used in FRM files (for downgrade compatibility),
but they are not printed by SHOW any more.
remove the hack where NO_DEFAULT_VALUE_FLAG was temporarily removed
from a field to initialize DEFAULT() functions in CHECK constraints
while disabling self-reference field checks.
Instead, initialize DEFAULT() functions in CHECK explicitly,
don't call check_field_expression_processor() for CHECK at all.
(Variant#3: Allow cross-charset comparisons, use a special
CHARSET_INFO to create lookup keys. Review input addressed.)
Equalities that compare utf8mb{3,4}_general_ci strings, like:
WHERE ... utf8mb3_key_col=utf8mb4_value (MB3-4-CMP)
can now be used to construct ref[const] access and also participate
in multiple-equalities.
This means that utf8mb3_key_col can be used for key-lookups when
compared with an utf8mb4 constant, field or expression using '=' or
'<=>' comparison operators.
This is controlled by optimizer_switch='cset_narrowing=on', which is
OFF by default.
IMPLEMENTATION
Item value comparison in (MB3-4-CMP) is done using utf8mb4_general_ci.
This is valid as any utf8mb3 value is also an utf8mb4 value.
When making index lookup value for utf8mb3_key_col, we do "Charset
Narrowing": characters that are in the Basic Multilingual Plane (=BMP) are
copied as-is, as they can be represented in utf8mb3. Characters that are
outside the BMP cannot be represented in utf8mb3 and are replaced
with U+FFFD, the "Replacement Character".
In utf8mb4_general_ci, the Replacement Character compares as equal to any
character that's not in BMP. Because of this, the constructed lookup value
will find all index records that would be considered equal by the original
condition (MB3-4-CMP).
Approved-by: Monty <monty@mariadb.org>
(Review input addressed)
(Added handling of UPDATE/DELETE and partitioning w/o index)
If the properties of the used collation allow, do the following
equivalent rewrites:
1. UPPER(key_col)=expr -> key_col=expr
expr=UPPER(key_col) -> expr=key_col
(also rewrite both sides of the equality at the same time)
2. UPPER(key_col) IN (constant-list) -> key_col IN (constant-list)
- Mark utf8mb{3,4}_general_ci as collations that allow this.
- Add optimizer_switch='sargable_casefold=ON' to control this.
(ON by default in this patch)
- Cover the rewrite in Optimizer Trace, rewrite name is
"sargable_casefold_removal".
Replacing my_casedn_str() called on local char[] buffer variables
to CharBuffer::copy_casedn() calls.
This is a sub-task for MDEV-31531 Remove my_casedn_str()
Details:
- Adding a helper template class IdentBuffer (a CharBuffer descendant),
which assumes utf8 data. Like CharBuffer, it's initialized to an empty
string in the constructor, but can be populated with lower-cased data
later.
- Adding a helper template class IdentBufferCasedn, which initializes
to lower case right in the constructor.
- Removing char[] buffers, replacing them to IdentBuffer and IdentBufferCasedn.
- Changing the data type of "db" and "table" parameters from
"const char*" to LEX_CSTRING in the following functions:
find_field_in_table_ref()
insert_fields()
set_thd_db()
mysql_grant()
to reuse IdentBuffer easeir.
Before this patch, the code in Item_field::print() used
this convention (described in sql_explain.h:ExplainDataStructureLifetime):
- By default, the table that Item_field refers to is accessible.
- ANALYZE and SHOW {EXPLAIN|ANALYZE} may print Items after some
temporary tables have been dropped. They use
QT_DONT_ACCESS_TMP_TABLES flag. When it is ON, Item_field::print
will not access the table it refers to, if it is a temp.table
The bug was that EXPLAIN statement also may compute subqueries (depending
on subquery context and @@expensive_subquery_limit setting). After the
computation, the subquery calls JOIN::cleanup(true) which drops some of
its temporary tables. Calling Item_field::print() that refer to such table
will cause an access to free'd memory.
In this patch, we take into account that query optimization can compute
a subquery and discard its temporary tables. Item_field::print() now
assumes that any temporary table might have already been dropped.
This means QT_DONT_ACCESS_TMP_TABLES flag is not needed - we imply it is
always present.
But we also make one exception: derived tables are not freed in
JOIN::cleanup() call. They are freed later in close_thread_tables(),
at the same time when regular tables are closed.
Because of that, Item_field::print may assume that temp.tables
representing derived tables are available.
Initial patch by: Rex Jonston
Reviewed by: Monty <monty@mariadb.org>
The problem is that the first execution of the prepared statement makes
a permanent optimization of converting the LEFT JOIN to an INNER JOIN.
This is based on the assumption that all the user parameters (?) are
always constants and that parameters to Item_cond() will not change value
from true and false between different executions.
(The example was using IS NULL, which will change value if parameter
depending on if the parameter is NULL or not).
The fix is to change Item_cond::fix_fields() and
Item_cond::eval_not_null_tables() to not threat user parameters as
constants. This will ensure that we don't do the LEFT_JOIN -> INNER
JOIN conversion that causes problems.
There is also some things that needs to be improved regarding
calculations of not_null_tables_cache as we get a different value for
WHERE 1 or t1.a=1
compared to
WHERE t1.a= or 1
Changes done:
- Mark Item_param with the PARAM flag to be able to quickly check
in Item_cond::eval_not_null_tables() if an item contains a
prepared statement parameter (just like we check for stored procedure
parameters).
- Fixed that Item_cond::not_null_tables_cache is not depending on
order of arguments.
- Don't call item->eval_const_cond() for items that are NOT on the top
level of the WHERE clause. This removed a lot of unnecessary
warnings in the test suite!
- Do not reset not_null_tables_cache for not top level items.
- Simplified Item_cond::fix_fields by calling eval_not_null_tables()
instead of having duplication of all the code in
eval_not_null_tables().
- Return an error if Item_cond::fix_field() generates an error
The old code did generate an error in some cases, but not in all
cases.
- Fixed all handling of the above error in make_cond_for_tables().
The error handling by the callers did not exists before which
could lead to asserts in many different places in the old code).
- All changes in sql_select.cc are just checking the return value of
fix_fields() and make_cond_for_tables() and returning an error
value if fix_fields() returns true or make_cond_for_tables()
returns NULL and is_error() is set.
- Mark Item_cond as const_item if all arguments returns true for
can_eval_in_optimize().
Reviewer: Sergei Petrunia <sergey@mariadb.com>
it was redundant, duplicating vcol_type == VCOL_GENERATED_STORED.
Note that VCOL_DEFAULT is not "stored", "stored vcol" means that after
rnd_next or index_read/etc the field value is already in the record[0]
and does not need to be calculated separately
* invoke check_expression() for all vcol_info's in
mysql_prepare_create_table() to check for FK CASCADE
* also check for SET NULL and SET DEFAULT
* to check against existing FKs when a vcol is added in ALTER TABLE,
old FKs must be added to the new_key_list just like other indexes are
* check columns recursively, if vcol1 references vcol2,
flags of vcol2 must be taken into account
* remove check_table_name_processor(), put that logic under
check_vcol_func_processor() to avoid walking the tree twice
Re-designed a way by that Item_trigger_field objects are arranged in memory.
Item_trigger_field objects created on parsing a trigger's statement
is now stored in a per statement list. All lists of Item_trigger_field
objects created on parsing the whole trigger's body are organized
in the structure "list of lists". So, use binary cycle to iterate every
Item_trigger_field object created on parsing a trigger body.
To organize the data structure 'list of lists' the new data member
Item_trigger_field::next_trig_field_list
is introduced that links lists in this hierarchy structure.
This re-design is performed in order to avoid refences to already
deleted items on re-compilation of failed trigger's statememt.
Referencing to already deleted items could take place on re-parsing
a trigger's statement since every Item created for a statement
being re-parsed is deleted before the statement be re-parsed,
but deleted items are still referenced from sp_head. So, to avoid
access to dangling references a per statement list of Item_trigger_field
objects are cleared right after the current SP statement be cleaned up
and before re-parsing be started.
When printing Item_direct_view_ref the printed field name must be
complemented with the view name/derived table alias.
For example, for "SELECT a FROM (SELECT a FROM t1) q" field `a`
in the select list must be printed as `q`.`a`.
But if the view was merged then the initial `q` does not make sense
any more so field `a` must be printed as `t1`.`a`
Rewrite datetime comparison conditions into sargeable. For example,
YEAR(col) <= val -> col <= YEAR_END(val)
YEAR(col) < val -> col < YEAR_START(val)
YEAR(col) >= val -> col >= YEAR_START(val)
YEAR(col) > val -> col > YEAR_END(val)
YEAR(col) = val -> col BETWEEN YEAR_START(val) AND YEAR_END(val)
Do the same with DATE(col), for example:
DATE(col) <= val -> col <= DAY_END(val)
After such a rewrite index lookup on column "col" can be employed
This bug could manifest itself at the first execution of prepared statement
created for queries using a materialized view defined as union. A crash
could happen for sure if the query contained a condition pushable into
the view and this condition was over the column defined via a complex string
expression requiring implicit conversion from one charset to another for
some of its sub-expressions. The bug could cause crashes when executing
PS for some other queries whose optimization needed building clones for
such expressions.
This bug was introduced in the patch for MDEV-29988 where the class
Item_direct_ref_to_item was added. The implementations of the virtual
methods get_copy() and build_clone() were invalid for the class and this
could cause crashes after the method build_clone() was called for
expressions containing objects of the Item_direct_ref_to_item type.
Approved by Sergei Golubchik <serg@mariadb.com>
* it isn't "pfs" function, don't call it Item_func_pfs,
don't use item_pfsfunc.*
* tests don't depend on performance schema, put in the main suite
* inherit from Item_str_ascii_func
* use connection collation, not utf8mb3_general_ci
* set result length in fix_length_and_dec
* do not set maybe_null
* use my_snprintf() where possible
* don't set m_value.ptr on every invocation
* update sys schema to use the format_pico_time()
* len must be size_t (compilation error on Windows)
* the correct function name for double->double is fabs()
* drop volatile hack
