Invoking memcpy() on a NULL pointer is undefined behaviour
(even if the length is 0) and gives the compiler permission to
assume that the pointer is nonnull. Recent versions of GCC
(starting with version 8) are more aggressively optimizing away
checks for NULL pointers. This undefined behaviour would cause
a SIGSEGV in the test main.func_encrypt on an optimized debug build
on GCC 10.2.0.
Problem:
The crash happened in FORMAT(double, dec>=31, 'de_DE').
The patch for MDEV-23118 (commit 0041dacc1b)
did not take into account that String::set_real() has a limit of 31
(FLOATING_POINT_DECIMALS) fractional digits. So for the range of 31..38
digits, set_real() switches to use:
- my_fcvt() - decimal point notation, e.g. 1.9999999999
- my_gcvt() - scientific notation, e.g. 1e22
my_gcvt() returned a shorter string than Item_func_format::val_str_ascii()
expected to get after the my_fcvt() call, so it crashed on assert.
Solution:
We cannot extend set_real() to use the my_fcvt() mode for the range of
31..38 fractional digits, because set_real() is used in a lot of places
and such a change will break everything.
Introducing String::set_fcvt() which always prints using my_fcvt()
for the whole range of decimals 0..38, supported by the FORMAT() function.
and
MDEV-23414 Assertion `res->charset() == item->collation.collation' failed in Type_handler_string_result::make_packed_sort_key_part
pack_sort_string() *must* take a collation from the Item, not from the
String value. Because when casting a string to _binary the original
String is not copied for performance reasons, it's reused but its
collation does not match Item's collation anymore.
Note, that String's collation cannot be simply changed to _binary,
because for an Item_string literal the original String must stay
unchanged for the duration of the query.
this partially reverts 61c15ebe32
- Adding optional qualifiers to data types:
CREATE TABLE t1 (a schema.DATE);
Qualifiers now work only for three pre-defined schemas:
mariadb_schema
oracle_schema
maxdb_schema
These schemas are virtual (hard-coded) for now, but may turn into real
databases on disk in the future.
- mariadb_schema.TYPE now always resolves to a true MariaDB data
type TYPE without sql_mode specific translations.
- oracle_schema.DATE translates to MariaDB DATETIME.
- maxdb_schema.TIMESTAMP translates to MariaDB DATETIME.
- Fixing SHOW CREATE TABLE to use a qualifier for a data type TYPE
if the current sql_mode translates TYPE to something else.
The above changes fix the reported problem, so this script:
SET sql_mode=ORACLE;
CREATE TABLE t2 AS SELECT mariadb_date_column FROM t1;
is now replicated as:
SET sql_mode=ORACLE;
CREATE TABLE t2 (mariadb_date_column mariadb_schema.DATE);
and the slave can unambiguously treat DATE as the true MariaDB DATE
without ORACLE specific translation to DATETIME.
Similar,
SET sql_mode=MAXDB;
CREATE TABLE t2 AS SELECT mariadb_timestamp_column FROM t1;
is now replicated as:
SET sql_mode=MAXDB;
CREATE TABLE t2 (mariadb_timestamp_column mariadb_schema.TIMESTAMP);
so the slave treats TIMESTAMP as the true MariaDB TIMESTAMP
without MAXDB specific translation to DATETIME.
- Better to use 'String *' directly.
- Added String::get_value(LEX_STRING*) for the few cases where we want to
convert a String to LEX_CSTRING.
Other things:
- Use StringBuffer for some functions to avoid mallocs
In main.index_merge_myisam we remove the test that was added in
commit a2d24def8c because
it duplicates the test case that was added in
commit 5af12e4635.
We must relax too strict debug assertions. For latin1_swedish_ci,
mtype=DATA_CHAR or mtype=DATA_VARCHAR will be used instead of
mtype=DATA_MYSQL or mtype=DATA_VARMYSQL. Likewise, some changes of
dtype_get_charset_coll() do not affect the data type encoding,
but only any indexes that are defined on the column.
Charset::same_encoding(): Check whether two charset-collations have
the same character set encoding.
dict_col_t::same_encoding(): Check whether two character columns
have the same character set encoding.
dict_col_t::same_type(): Check whether two columns have a compatible
data type encoding.
dict_col_t::same_format(), dict_table_t::instant_column(): Do not
compare mtype or the charset-collation of prtype directly.
Rely on dict_col_t::same_type() instead.
dtype_get_charset_coll(): Narrow the return type to uint16_t.
This is a refined version of a fix that was developed by
Thirunarayanan Balathandayuthapani.
The old code to print partition values was too complicated:
- it created new Items for character set conversion purposes.
- it mixed string conversion and partition error reporting
in the same code blocks.
Simplifying the code as follows:
- Adding helper methods String::can_be_safely_convert_to() and
String::append_introducer_and_hex().
- Adding DBUG_EXECUTE_IF("generate_partition_syntax_for_frm", push_warning...)
into generate_partition_syntax_for_frm(), to test the PARTITON
clause written to FRM. Adding test partition_utf8-debug.test for this.
- Removing functions get_cs_converted_part_value_from_string() and
get_cs_converted_string_value. Changing get_partition_column_description()
to use Type_handler::partition_field_append_value() instead.
This makes SHOW CREATE TABLE and SELECT FROM I_S.PARTITIONS
use the same code path.
- Changing Type_handler::partition_field_append_value() not to
call convert_charset_partition_constant(), to avoid creating a new Item
for string conversion pursposes.
Rewritting the code to use only String methods.
- Removing error reporting code (ER_PARTITION_FUNCTION_IS_NOT_ALLOWED)
from Type_handler::partition_field_append_value().
The error is correctly detected and reported on the caller level.
So error reporting was redundant here.
Also:
- Moving methods Type_handler::partition_field_*() from sql_partition.cc
to sql_type.cc. This fixes compilation problem with -DPLUGIN_PARTITION=NO,
earlier introduced by the patch for MDEV-20831.
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.
Patch is about two cases:
1) On some collate changes it's possible to rebuild only secondary indexes
2) For non-indexed columns collate can be changed INSTANTly
Implemented mostly in Field_{string,varstring,blob}::is_equal().
Make this method return how exactly collationa differs.
This information is later used by fill_alter_inplace_info() to pass
correct info to engine.
Introduced a print_key_value function to makes sure that the trace prints data in readable format
for readable characters and the rest of the characters are printed as hexadecimal.
This patch fixes:
- MDEV-19284 INSTANT ALTER with ucs2-to-utf16 conversion produces bad data
- MDEV-19285 INSTANT ALTER from ascii_general_ci to latin1_general_ci produces corrupt data
These regressions were introduced in 10.4.3 by:
- MDEV-15564 Avoid table rebuild in ALTER TABLE on collation or charset changes
Changes:
1. Cleanup: Adding a helper method
Field_longstr::csinfo_change_allows_instant_alter(),
to remove some duplicate code in field.cc.
2. Cleanup: removing Type_handler::Charsets_are_compatible() and static
function charsets_are_compatible() and
introducing new methods in the recently added class Charset instead:
- encoding_allows_reinterpret_as()
- encoding_and_order_allow_reinterpret_as()
3. Bug fix: Removing the code that allowed instant conversion for
ascii-to->8bit and ucs2-to->utf16.
This actually fixes MDEV-19284 and MDEV-19285.
4. Bug fix: Adding a helper method Charset::collation_specific_name().
The old corresponding code in Type_handler::Charsets_are_compatible()
was not safe against (badly named) user-defined collations whose
character set name can be longer than collation name.
The MDEV-17262 commit 26432e49d3
was skipped. In Galera 4, the implementation would seem to require
changes to the streaming replication.
In the tests archive.rnd_pos main.profiling, disable_ps_protocol
for SHOW STATUS and SHOW PROFILE commands until MDEV-18974
has been fixed.
