1. Renaming Type_handler_json to Type_handler_json_longtext
There will be other JSON handlers soon, e.g. Type_handler_json_varchar.
2. Making the code more symmetric for data types:
- Adding a new virtual method
Type_handler::Column_definition_validate_check_constraint()
- Moving JSON-specific code from sql_yacc.yy to
Type_handler_json_longtext::Column_definition_validate_check_constraint()
3. Adding new files sql_type_json.cc and sql_type_json.h
and moving Type_handler+JSON related code into these files.
Allow ALGORITHM=INSTANT (or avoid touching any data)
when changing the collation, or in some cases, the character set,
of a non-indexed CHAR or VARCHAR column. There is no penalty
for subsequent DDL or DML operations, and compatibility with
older MariaDB versions will be unaffected.
Character sets may be changed when the old encoding is compatible
with the new one. For example, changing from ASCII to anything
ASCII-based, or from 3-byte to 4-byte UTF-8 can sometimes be
performed instantly.
This is joint work with Eugene Kosov.
The test cases as well as ALTER_CONVERT_TO, charsets_are_compatible(),
Type_handler::Charsets_are_compatible() are his work.
The Field_str::is_equal(), Field_varstring::is_equal() and
the InnoDB changes were mostly rewritten by me due to conflicts
with MDEV-15563.
Limitations:
Changes of indexed columns will still require
ALGORITHM=COPY. We should allow ALGORITHM=NOCOPY and allow
the indexes to be rebuilt inside the storage engine,
without copying the entire table.
Instant column size changes (in bytes) are not supported by
all storage engines.
Instant CHAR column changes are only allowed for InnoDB
ROW_FORMAT=REDUNDANT. We could allow this for InnoDB
when the CHAR internally uses a variable-length encoding,
say, when converting from 3-byte UTF-8 to 4-byte UTF-8.
Instant VARCHAR column changes are allowed for InnoDB
ROW_FORMAT=REDUNDANT, and for others only if the size
in bytes does not change from 128..255 bytes to more
than 256 bytes.
Inside InnoDB, this slightly changes the way how MDEV-15563
works and fixes the result of the innodb.instant_alter_extend test.
We change the way how ALTER_COLUMN_EQUAL_PACK_LENGTH_EXT
is handled. All column extension, type changes and renaming
now go through a common route, except when ctx->is_instant()
is in effect, for example, instant ADD or DROP COLUMN has
been initiated. Only in that case we will go through
innobase_instant_try() and rewrite all column metadata.
get_type(field, prtype, mtype, len): Convert a SQL data type into
InnoDB column metadata.
innobase_rename_column_try(): Remove the update of SYS_COLUMNS.
innobase_rename_or_enlarge_column_try(): New function,
replacing part of innobase_rename_column_try() and all of
innobase_enlarge_column_try(). Also changes column types.
innobase_rename_or_enlarge_columns_cache(): Also change
the column type.
When creating a field of type JSON, it will be automatically
converted to TEXT with CHECK (json_valid(`a`)), if there wasn't any
previous check for the column.
Additional things:
- Added two bug fixes that was found while testing JSON. These bug
fixes has also been pushed to 10.3 (with a test case), but as they
where minimal and needed to get this task done and tested, the fixes
are repeated here.
- CREATE TABLE ... SELECT drops constraints for columns that
are both in the create and select part.
- If one has both a default expression and check constraint for a
column, one can get the error "Expression for field `a` is refering
to uninitialized field `a`.
- Removed some duplicate MYSQL_PLUGIN_IMPORT symbols
MDEV-17625 Different warnings when comparing a garbage to DATETIME vs TIME
- Splitting processes of data type conversion (to TIME/DATE,DATETIME)
and warning generation.
Warning are now only get collected during conversion (in an "int" variable),
and are pushed in the very end of conversion (not in parallel).
Warnings generated by the low level routines str_to_xxx() and number_to_xxx()
can now be changed at the end, when TIME_FUZZY_DATES is applied,
from "Invalid value" to "Truncated invalid value".
Now "Illegal value" is issued only when the low level routine returned
an error and TIME_FUZZY_DATES was not set. Otherwise, if the low level
routine returned "false" (success), or if NULL was converted to a zero
datetime by TIME_FUZZY_DATES, then "Truncated illegal value"
is issued. This gives better warnings.
- Methods Type_handler::Item_get_date() and
Type_handler::Item_func_hybrid_field_type_get_date() now only
convert and collect warning information, but do not push warnings.
- Changing the return data type for Type_handler::Item_get_date()
and Type_handler::Item_func_hybrid_field_type_get_date() from
"bool" to "void". The conversion result (success vs error) can be
checked by testing ltime->time_type. MYSQL_TIME_{NONE|ERROR}
mean mean error, other values mean success.
- Adding new wrapper methods Type_handler::Item_get_date_with_warn() and
Type_handler::Item_func_hybrid_field_type_get_date_with_warn()
to do conversion followed by raising warnings, and changing
the code to call new Type_handler::***_with_warn() methods.
- Adding a helper class Temporal::Status, a wrapper
for MYSQL_TIME_STATUS with automatic initialization.
- Adding a helper class Temporal::Warn, to collect warnings
but without actually raising them. Moving a part of ErrConv
into a separate class ErrBuff, and deriving both Temporal::Warn
and ErrConv from ErrBuff. The ErrBuff part of Temporal::Warn
is used to collect textual representation of the input data.
- Adding a helper class Temporal::Warn_push. It's used
to collect warning information during conversion, and
automatically pushes warnings to the diagnostics area
on its destructor time (in case of non-zero warning).
- Moving more code from various functions inside class Temporal.
- Adding more Temporal_hybrid constructors and
protected Temporal methods make_from_xxx(),
which convert and only collect warning information, but do not
actually raise warnings.
- Now the low level functions str_to_datetime() and str_to_time()
always set status->warning if the return value is "true" (error).
- Now the low level functions number_to_time() and number_to_datetime()
set the "*was_cut" argument if the return value is "true" (error).
- Adding a few DBUG_ASSERTs to make sure that str_to_xxx() and
number_to_xxx() always set warnings on error.
- Adding new warning flags MYSQL_TIME_WARN_EDOM and MYSQL_TIME_WARN_ZERO_DATE
for the code symmetry. Before this change there was a special
code path for (rc==true && was_cut==0) which was treated by
Field_temporal::store_invalid_with_warning as "zero date violation".
Now was_cut==0 always means that there are no any error/warnings/notes
to be raised, not matter what rc is.
- Using new Temporal_hybrid constructors in combination with
Temporal::Warn_push inside str_to_datetime_with_warn(),
double_to_datetime_with_warn(), int_to_datetime_with_warn(),
Field::get_date(), Item::get_date_from_string(), and a few other places.
- Removing methods Dec_ptr::to_datetime_with_warn(),
Year::to_time_with_warn(), my_decimal::to_datetime_with_warn(),
Dec_ptr::to_datetime_with_warn().
Fixing Sec6::to_time() and Sec6::to_datetime() to
convert and only collect warnings, without raising warnings.
Now warning raising functionality resides in Temporal::Warn_push.
- Adding classes Longlong_hybrid_null and Double_null, to
return both value and the "IS NULL" flag. Adding methods
Item::to_double_null(), to_longlong_hybrid_null(),
Item_func_hybrid_field_type::to_longlong_hybrid_null_op(),
Item_func_hybrid_field_type::to_double_null_op().
Removing separate classes VInt and VInt_op, as they
have been replaced by a single class Longlong_hybrid_null.
- Adding a helper method Temporal::type_name_by_timestamp_type(),
moving a part of make_truncated_value_warning() into it,
and reusing in Temporal::Warn::push_conversion_warnings().
- Removing Item::make_zero_date() and
Item_func_hybrid_field_type::make_zero_mysql_time().
They provided duplicate functionality.
Now this code resides in Temporal::make_fuzzy_date().
The latter is now called for all Item types when data type
conversion (to DATE/TIME/DATETIME) is involved, including
Item_field and Item_direct_view_ref.
This fixes MDEV-17563: Item_direct_view_ref now correctly converts
NULL to a zero date when TIME_FUZZY_DATES says so.
C++ does not guarantee the order of parameter evaluation.
It was wrong to pass item->val_int() and item->null_value
at the same time to any function or constructor.
Adding a new helper class Longlong_null, and new methods
Item::to_longlong_null() and Item_func_hybrid_field_type::to_longlong_null_op(),
which make sure to properly call val_int()/int_op() and test null_value.
Reorganizing the rest of the code accordingly.
The problem happened because {{Field_xxx::store(longlong nr, bool unsigned_val)}} erroneously passed {{unsigned_flag}} to the {{usec}} parameter of this constructor:
{code:cpp}
Datetime(int *warn, longlong sec, ulong usec, date_conv_mode_t flags)
{code}
1. Changing Time and Datetime constructors to accept data as Sec6 rather than as
longlong/double/my_decimal, so it's not possible to do such mistakes
in the future. Additional good effect of these changes:
- This reduced some amount of similar code (minus ~35 lines).
- The code now does not rely on the fact that "unsigned_flag" is
not important inside Datetime().
The constructor always gets all three parts: sign, integer part,
fractional part. The simple the better.
2. Fixing Field_xxx::store() to use the new Datetime constructor format.
This change actually fixes the problem.
3. Adding "explicit" keyword to all Sec6 constructors,
to avoid automatic hidden conversion from double/my_decimal to Sec6,
as well as from longlong/ulonglong through double to Sec6.
4. Change#1 caused (as a dependency) changes in a few places
with code like this:
bool neg= nr < 0 && !unsigned_val;
ulonglong value= m_neg ? (ulonglong) -nr : (ulonglong) nr;
These fragments relied on a non-standard behavior with
the operator "minus" applied to the lowest possible negative
signed long long value. This can lead to different results
depending on the platform and compilation flags.
We have fixed such bugs a few times already.
So instead of modifying the old wrong code to a new wrong code,
replacing all such fragments to use Longlong_hybrid,
which correctly handles this special case with -LONGLONG_MIN
in its method abs().
This also reduced the amount of similar code
(1 or 2 new lines instead 3 old lines in all 6 such fragments).
5. Removing ErrConvInteger(longlong nr, bool unsigned_flag= false)
and adding ErrConvInteger(Longlong_hybrid) instead, to encourage
use of safe Longlong_hybrid instead of unsafe pairs nr+neg.
6. Removing unused ErrConvInteger from Item_cache_temporal::get_date()
Problems:
Functions LEAST() and GREATEST() in TIME context, as well as functions
TIMESTAMP(a,b) and ADDTIME(a,b), returned confusing results when the
input TIME-alike value in a number or in a string was out of the TIME
supported range.
In case of TIMESTAMP(a,b) and ADDTIME(a,b), the second argument
value could get extra unexpected digits. For example, in:
ADDTIME('2001-01-01 00:00:00', 10000000) or
ADDTIME('2001-01-01 00:00:00', '1000:00:00')
the second argument was converted to '838:59:59.999999'
with six fractional digits, which contradicted "decimals"
previously set to 0 in fix_length_and_dec().
These unexpected fractional digits led to confusing function results.
Changes:
1. GREATEST(), LEAST()
- fixing Item_func_min_max::get_time_native()
to respect "decimals" set by fix_length_and_dec().
If a value of some numeric or string time-alike argument
goes outside of the TIME range and gets limited to '838:59:59.999999',
it's now right-truncated to the correct fractional precision.
- fixing, Type_handler_temporal_result::Item_func_min_max_fix_attributes()
to take into account arguments' time_precision() or datetime_precision(),
rather than rely on "decimals" calculated by the generic implementation
in Type_handler::Item_func_min_max_fix_attributes(). This makes
GREATEST() and LEAST() return better data types, with the same
fractional precision with what TIMESTAMP(a,b) and ADDTIME(a,b) return
for the same arguments, and with DATE(a) and TIMESTAMP(a).
2. Item_func_add_time and Item_func_timestamp
It was semantically wrong to apply the limit of the TIME data type
to the argument "b", which plays the role of "INTERVAL DAY TO SECOND" here.
Changing the code to fetch the argument "b" as INTERVAL rather than as TIME.
The low level routine calc_time_diff() now gets the interval
value without limiting to '838:59:59.999999', so in these examples:
ADDTIME('2001-01-01 00:00:00', 10000000)
ADDTIME('2001-01-01 00:00:00', '1000:00:00')
calc_time_diff() gets '1000:00:00' as is. The SQL function result
now gets limited to the supported result data type range
(datetime or time) inside calc_time_diff(), which now calculates
the return value using the real fractional digits that
came directly from the arguments (without the effect of limiting
to the TIME range), so the result does not have any unexpected
fractional digits any more.
Detailed changes in TIMESTAMP() and ADDTIME():
- Adding a new class Interval_DDhhmmssff. It's similar to Time, but:
* does not try to parse datetime format, as it's not needed for
functions TIMESTAMP() and ADDTIME().
* does not cut values to '838:59:59.999999'
The maximum supported Interval_DDhhmmssff's hard limit is
'UINT_MAX32:59:59.999999'. The maximum used soft limit is:
- '87649415:59:59.999999' (in 'hh:mm:ss.ff' format)
- '3652058 23:59:59.999999' (in 'DD hh:mm:ss.ff' format)
which is a difference between:
- TIMESTAMP'0001-01-01 00:00:00' and
- TIMESTAMP'9999-12-31 23:59:59.999999'
(the minimum datetime that supports arithmetic, and the
maximum possible datetime value).
- Fixing get_date() methods in the classes related to functions
ADDTIME(a,b) and TIMESTAMP(a,b) to use the new class Interval_DDhhmmssff
for fetching data from the second argument, instead of get_date().
- Fixing fix_length_and_dec() methods in the classes related
to functions ADDTIME(a,b) and TIMESTAMP(a,b) to use
Interval_DDhhmmssff::fsp(item) instead of item->time_precision()
to get the fractional precision of the second argument correctly.
- Splitting the low level function str_to_time() into smaller pieces
to reuse the code. Adding a new function str_to_DDhhmmssff(), to
parse "INTERVAL DAY TO SECOND" values.
After these changes, functions TIMESTAMP() and ADDTIME()
return much more predictable results, in terms of fractional
digits, and in terms of the overall result.
The full ranges of DATETIME and TIME values are now covered by TIMESTAMP()
and ADDTIME(), so the following can now be calculated:
SELECT ADDTIME(TIMESTAMP'0001-01-01 00:00:00', '87649415:59:59.999999');
-> '9999-12-31 23:59:59.999999'
SELECT TIMESTAMP(DATE'0001-01-01', '87649415:59:59.999999')
-> '9999-12-31 23:59:59.999999'
SELECT ADDTIME(TIME'-838:59:59.999999', '1677:59:59.999998');
-> '838:59:59.999999'
Fixing C++ function check_date() to get the "fuzzydate" as
date_mode_t rather than ulonglong, so conversion from
date_time_t to ulonglong is now done inside C++ check_date(),
and no conversion is needed in the callers' code.
As an additional safety, modified the code not to pass
TIME_FUZZY_DATE to the low level C functions:
- check_date()
- str_to_datetime()
- str_to_time()
- number_to_datetime()
because TIME_FUZZY_DATE is known only on the C++ level,
C functions do not know it.
Soon we'll be adding more flags into the C++ level (i.e. to date_time_t),
e.g. for rounding. It's a good idea to prevent passing C++ specific
flags into pure C routines before this change.
Asserts were added into the affected C functions to verify
that the caller passed only known C level flags.
Also fixes:
MDEV-17330 Wrong result for 0 + LEAST(TIME'-10:00:00',TIME'10:00:00')
Problems:
1. These methods did not take into account the current session date flags
and passed date_mode_t(0) to func->get_date():
Type_handler_temporal_result::Item_func_min_max_val_real
Type_handler_temporal_result::Item_func_min_max_val_int
Type_handler_temporal_result::Item_func_min_max_val_decimal
Fixing to pass sql_mode_for_dates(thd) instead of date_mode_t(0).
Note, sql_mode_for_dates(thd) is only needed for DATE/DATETIME
data types. It is not needed for TIME.
So splitting value methods Type_handler_temporal_result::Item_func_min_max_xxx
into individual implementations for
Type_handler_{time|date|datetime|timestamp}_common
and, instead of calling get_date(), reusing inside classes
Time(), Date(), Datetime() and their methods to_longlong().
sql_mode_for_dates(thd) is automatically passed to get_date()
inside Date() and Datetime() constructors.
The switch to classes also fixed the problem reported in MDEV-17330.
Type_handler_temporal_result::Item_func_min_max_val_int() used to
call TIME_to_ulonglong(), which was not correct for TIME.
Changing the code to use Time().to_longlong() solved this.
2. Type_handler_temporal_result::Item_func_min_max_get_date
also did not take into account the current session
date flags in case of conversion from DATE/DATETIME to time
and passed date_mode_t(0) to get_date_native().
Fixing to pass sql_mode_for_dates(thd) in case of conversion
from DATE/DATETIME to TIME.
The patch for MDEV-16928 added a few new asserts to check that
time, date, datetime values are valid and consistent after initialization.
One of the new asserts caught an improper initialization in
Time::make_from_datetime_with_days_diff()
(the former function calc_datetime_days_diff()).
If the YYYYMM part is not zero after unpack time
we have an out-of-range TIME value.
- Adding a helper class Sec6 to store (neg,seconds,microseconds)
- Adding a helper class VSec6 (Sec6 with a flag for "IS NULL")
- Wrapping related functions as methods of Sec6;
* number_to_datetime()
* number_to_time()
* my_decimal2seconds()
* Item::get_seconds()
* A big piece of code in Item_func_sec_to_time::get_date()
- Using the new classes in places where second-to-temporal
conversion takes place:
* Field_timestamp::store(double)
* Field_timestamp::store(longlong)
* Field_timestamp_with_dec::store_decimal(my_decimal)
* Field_temporal_with_date::store(double)
* Field_temporal_with_date::store(longlong)
* Field_time::store(double)
* Field_time::store(longlong)
* Field_time::store_decimal(my_decimal)
* Field_temporal_with_date::store_decimal(my_decimal)
* get_interval_value()
* Item_func_sec_to_time::get_date()
* Item_func_from_unixtime::get_date()
* Item_func_maketime::get_date()
This change simplifies these methods and functions a lot.
- Warnings are now sent at VSec6 initialization time, when the source
data is available in its original data type representation.
If Sec6::to_time() or Sec6::to_datetime() truncate data again during
conversion to MYSQL_TIME, they send warnings, but only if no warnings
were sent during VSec6 initialization. This helps prevents double warnings.
The call for val_str() in Item_func_sec_to_time::get_date() is not
needed any more, so it's removed. This change actually fixes the problem.
As a good effect, FROM_UNIXTIME() and MAKETIME() now also send warnings
in case if the seconds arguments is out of range. Previously these
functions returned NULL silently.
- Splitting the code in the global function make_truncated_value_warning()
into a number of methods THD::raise_warning_xxxx().
This was needed to reuse the logic that chooses between:
* ER_TRUNCATED_WRONG_VALUE
* ER_WRONG_VALUE
* ER_TRUNCATED_WRONG_VALUE_FOR_FIELD
for non-temporal data types (Sec6).
- Removing:
* Item::get_seconds()
* number_to_time_with_warn()
as this code now resides inside methods of Sec6.
- Cleanup (changes that are not directly related to the fix):
* Removing calls for field_name_or_null() and passing NULL instead
in Item_func_hybrid_field_type::get_date_from_{int|real}_op,
because Item_func_hybrid_field_type::field_name_or_null()
always returns NULL
* Replacing a number of calls for make_truncated_value_warning()
to calls for THD::raise_warning_xxx(). In these places
we know that the execution went through a certain
branch of make_truncated_value_warning(),
(e.g. the exact error code is known, or field name is always NULL,
or field name is always not-NULL). So calls for the entire
make_truncated_value_warning() after splitting are not necessary.
Adding new methods:
- virtual void Type_handler::Column_definition_reuse_fix_attributes()
according to the MDEV description
- virtual uint32 Field::character_octet_length()
To simplify handling of Column_definition::length for
TEXT and VARCHAR columns (with and without compression).
MDEV-16426 Optimizer erroneously treats equal constants of different formats as same
A cleanup for MDEV-14630: fixing a crash in Item_decimal::eq().
Problems:
- old implementations of Item_decimal::eq() and
Item_temporal_literal::eq() were not symmetric
with Item_param::eq(), this caused MDEV-11361.
- old implementations for DECIMAL and temporal data types
did not take into account that in case when eq() is called
with binary_cmp==true, {{eq()}} should check not only equality
of the two values, but also equality if their decimal precision.
This cuases MDEV-16426.
- Item_decimal::eq() crashes with "item" pointing
to a non-DECIMAL value. Before MDEV-14630
non-DECIMAL values were filtered out by the test:
type() == item->type()
as literals of different types had different type().
After MDEV-14630 type() for literals of all data types return CONST_ITEM.
This caused failures in tests:
./mtr engines/iuds.insert_number
./mtr --ps --embedded main.explain_slowquerylog
(revealed by buildbot)
The essence of the fix:
Making literals and Item_param reuse the same code to avoid
asymmetries between Item_param::eq(Item_literal) and
Item_literal::eq(Item_param), now and in the future, and to
avoid code duplication between Item_literal and Item_param.
Adding tests for "decimals" for DECIMAL and temporal data types,
to treat constants of different scale as not equal when "binary_cmp"
is "true".
Details:
1. Adding a helper class Item_const to extract constant values from Items easier
2. Deriving Item_basic_value from Item_const
3. Joining Type_handler::Item_basic_value_eq() and Item_basic_value_bin_eq()
into a single method with an extra "binary_cmp" argument
(it looks simple this way) and renaming the new method to Item_const_eq().
Modifying its implementations to operate with
Item_const instead of Item_basic_value.
4. Adding a new class Type_handler_hex_hybrid,
to handle hex constants like 0x616263.
5. Removing Item::VARBIN_ITEM and fixing Item_hex_constant to
use type_handler_hex_hybrid instead of type_handler_varchar.
Item_hex_hybrid::type() now returns CONST_ITEM, like all
other literals do.
6. Move virtual methods Item::type_handler_for_system_time() and
Item::cast_to_int_type_handler() from Item to Type_handler.
7. Removing Item_decimal::eq() and Item_temporal_literal::eq().
These classes are now handled by the generic Item_basic_value::eq().
8. Implementing Type_handler_temporal_result::Item_const_eq()
and Type_handler_decimal_result::Item_const_eq(),
this fixes MDEV-11361.
9. Adding tests for "decimals" into
Type_handler_decimal_result::Item_const_eq() and
Type_handler_temporal_result::Item_const_eq()
in case if "binary_cmp" is true.
This fixes MDEV-16426.
10. Moving Item_cache out of Item_basic_value.
They share nothing. It simplifies implementation
of Item_basic_value::eq(). Deriving Item_cache
directly from Item.
11. Adding class DbugStringItemTypeValue, which
used Item::print() internally, and using
in instead of the old debug printing code.
This gives nicer output in func_debug.result.
Changes N5 and N6 do not directly relate to the bugs fixed,
but make the code fully symmetric across all literal types.
Without a new handler Type_handler_hex_hybrid we'd have
to keep two code branches (for regular literals and for
hex hybrid literals).
Now the boolean data type is preserved in hybrid functions and MIN/MAX,
so COALESCE(bool_expr,bool_expr) and MAX(bool_expr) are correctly
detected by JSON_OBJECT() as being boolean rather than numeric expressions.
MDEV-16100 FOR SYSTEM_TIME erroneously resolves string user variables as transaction IDs
Problem:
Vers_history_point::resolve_unit() tested item->result_type() before
item->fix_fields() was called.
- Item_func_get_user_var::result_type() returned REAL_RESULT by default.
This caused MDEV-16100.
- Item_func_sp::result_type() crashed on assert.
This caused MDEV-16094
Changes:
1. Adding item->fix_fields() into Vers_history_point::resolve_unit()
before using data type specific properties of the history point
expression.
2. Adding a new virtual method Type_handler::Vers_history_point_resolve_unit()
3. Implementing type-specific
Type_handler_xxx::Type_handler::Vers_history_point_resolve_unit()
in the way to:
a. resolve temporal and general purpose string types to TIMESTAMP
b. resolve BIT and general purpose INT types to TRANSACTION
c. disallow use of non-relevant data type expressions in FOR SYSTEM_TIME
Note, DOUBLE and DECIMAL data types are disallowed intentionally.
- DOUBLE does not have enough precision to hold huge BIGINT UNSIGNED values
- DECIMAL rounds on conversion to INT
Both lack of precision and rounding might potentionally lead to
very unpredictable results when a wrong transaction ID would be chosen.
If one really wants dangerous use of DOUBLE and DECIMAL, explicit CAST
can be used:
FOR SYSTEM_TIME AS OF CAST(double_or_decimal AS UNSIGNED)
QQ: perhaps DECIMAL(N,0) could still be allowed.
4. Adding a new virtual method Item::type_handler_for_system_time(),
to make HEX hybrids and bit literals work as TRANSACTION rather
than TIMESTAMP.
5. sql_yacc.yy: replacing the rule temporal_literal to "TIMESTAMP TEXT_STRING".
Other temporal literals now resolve to TIMESTAMP through the new
Type_handler methods. No special grammar needed. This removed
a few shift/resolve conflicts.
(TIMESTAMP related conflicts in "history_point:" will be removed separately)
6. Removing the "timestamp_only" parameter from
vers_select_conds_t::resolve_units() and Vers_history_point::resolve_unit().
It was a hint telling that a table did not have any TRANSACTION-aware
system time columns, so it's OK to resolve to TIMESTAMP in case of uncertainty.
In the new reduction it works as follows:
- the decision between TIMESTAMP and TRANSACTION is first made
based only on the expression data type only
- then, in case if the expression resolved to TRANSACTION, the table
is checked if TRANSACTION-aware columns really exist.
This way is safer against possible ALTER TABLE statements changing
ROW START and ROW END columns from "BIGINT UNSIGNED" to "TIMESTAMP(x)"
or the other way around.
