It was used for get_datetime_value() and for thd->is_error().
But in fact, get_datetime_value() never used thd argument, because the
cache ptr argument was NULL. And thd->is_error() check was not needed
at that place at all.
it used current_thd->alloc() and allocated on the thd's execution arena,
not on table->expr_arena.
Remove THD::arena_for_cached_items that is temporarily set in
update_virtual_fields(), and replaces THD arena in get_datetime_value().
Instead set THD arena to table->expr_arena for the whole duration
of update_virtual_fields()
Item_func_le included Arg_comparator. Arg_comparator remembered
the current_thd during fix_fields and used that value during
execution to allocate Item_cache in get_datetime_value().
But for vcols fix_fields and val_int can happen in different threads.
Same bug for Item_func_in using in_datetime or cmp_item_datetime,
both also remembered current_thd at fix_fields() to use it later
for get_datetime_value().
As a fix, these objects no longer remember the current_thd,
and get_datetime_value() uses current_thd at run time. This
should not increase the number of current_thd calls much, as
Item_cache is created only once anyway.
- Changed error handlers interface so that they can change error level in
the handler
- Give warnings and errors when calculating virtual columns
- On insert/update error is fatal in strict mode.
- SELECT and DELETE will only give a warning if a virtual field generates an error
- Added VCOL_UPDATE_FOR_DELETE and VCOL_UPDATE_INDEX_FOR_REPLACE to be able to
easily detect in update_virtual_fields() if we should use an error
handler to mask errors or not.
Problem was that one internal record buffer in MYISAM was not big enough to handle virtual fields.
Fixed by extending buffer.
Fixed test case to 79 characters
Found and fixed 2 problems:
- Filesort addon fields didn't mark virtual columns properly
- multi-range-read calculated vcol bitmap but was not using it.
This caused wrong vcol field to be calculated on read, which caused the assert.
When updating a table with virtual BLOB columns, the following might
happen:
- an old record is read from the table, it has no virtual blob values
- update_virtual_fields() is run, vcol blob gets its value into the
record. But only a pointer to the value is in the table->record[0],
the value is in Field_blob::value String (but it doesn't have to be!
it can be in the record, if the column is just a copy of another
columns: ... b VARCHAR, c BLOB AS (b) ...)
- store_record(table,record[1]), old record now is in record[1]
- fill_record() prepares new values in record[0], vcol blob is updated,
new value replaces the old one in the Field_blob::value
- now both record[1] and record[0] have a pointer that points to the
*new* vcol blob value. Or record[1] has a pointer to nowhere if
Field_blob::value had to realloc.
To fix this I have introduced a new String object 'read_value' in
Field_blob. When updating virtual columns when a row has been read,
the allocated value is stored in 'read_value' instead of 'value'. The
allocated blobs for the new row is stored in 'value' as before.
I also made, as a safety precaution, the insert delayed handling of
blobs more general by using value to store strings instead of the
record. This ensures that virtual functions on delayed insert should
work in as in the case of normal insert.
Triggers are now properly updating the read, write and vcol maps for used
fields. This means that we don't need VCOL_UPDATE_FOR_READ_WRITE anymore
and there is no need for any other special handling of triggers in
update_virtual_fields().
To be able to test how many times virtual fields are invoked, I also
relaxed rules that one can use local (@) variables in DEFAULT and non
persistent virtual field expressions.
otherwise we'd need to store sql_mode *per vcol*
(consider CREATE INDEX...) and how SHOW CREATE TABLE would
support that?
Additionally, get rid of vcol::expr_str, just to make sure
the string is always generated and never leaked in the
original form.
* remove old 5.2+ InnoDB support for virtual columns
* enable corresponding parts of the innodb-5.7 sources
* copy corresponding test cases from 5.7
* copy detailed Alter_inplace_info::HA_ALTER_FLAGS flags from 5.7
- and more detailed detection of changes in fill_alter_inplace_info()
* more "innodb compatibility hooks" in sql_class.cc to
- create/destroy/reset a THD (used by background purge threads)
- find a prelocked table by name
- open a table (from a background purge thread)
* different from 5.7:
- new service thread "thd_destructor_proxy" to make sure all THDs are
destroyed at the correct point in time during the server shutdown
- proper opening/closing of tables for vcol evaluations in
+ FK checks (use already opened prelocked tables)
+ purge threads (open the table, MDLock it, add it to tdc, close
when not needed)
- cache open tables in vc_templ
- avoid unnecessary allocations, reuse table->record[0] and table->s->default_values
- not needed in 5.7, because it overcalculates:
+ tell the server to calculate vcols for an on-going inline ADD INDEX
+ calculate vcols for correct error messages
* update other engines (mroonga/tokudb) accordingly
When updating a table with virtual BLOB columns, the following might happen:
- an old record is read from the table, it has no virtual blob values
- update_virtual_fields() is run, vcol blob gets its value into the
record. But only a pointer to the value is in the table->record[0],
the value is in Field_blob::value String (but it doesn't have to be!
it can be in the record, if the column is just a copy of another
columns: ... b VARCHAR, c BLOB AS (b) ...)
- store_record(table,record[1]), old record now is in record[1]
- fill_record() prepares new values in record[0], vcol blob is updated,
new value replaces the old one in the Field_blob::value
- now both record[1] and record[0] have a pointer that points to the
*new* vcol blob value. Or record[1] has a pointer to nowhere if
Field_blob::value had to realloc.
To resolve this we unlink vcol blobs from the pointer to the
data (in the record[1]). Because the value is not *always* in
the Field_blob::value String, we need to remember what blobs
were unlinked. The orphan memory must be freed manually.
To complicate the matter, ha_update_row() is also used in
multi-update, in REPLACE, in INSERT ... ON DUPLICATE KEY UPDATE,
also on REPLACE ... SELECT, REPLACE DELAYED, and LOAD DATA REPLACE, etc
multi-update was setting up read_set/vcol_set in
multi_update::initialize_tables() that is invoked after
the optimizer (JOIN::optimize_inner()). But some rows - if they're from
const tables - will be read already in the optimizer, and these rows
will not have all necessary column/vcol values.
* multi_update::initialize_tables() uses results from the optimizer
and cannot be moved to be called earlier.
* multi_update::prepare() is called before the optimizer, but
it cannot set up read_set/vcol_set, because the optimizer
might reset them (see SELECT_LEX::update_used_tables()).
As a fix I've added a new method, select_result::prepare_to_read_rows(),
it's called from inside the optimizer just before make_join_statistics().
This fixes a bug where handler::read_range_first (for example)
needed to compare vcol values that were not calculated yet.
As a bonus it fixes few cases where vcols were calculated twice
cannot use TABLE:merge_keys for that, because Field::part_of_key
was designed to mark fields for KEY_READ, so a field is not a
"part of key", if only prefix of the field is.
* don't issue an error for ER_KEY_BASED_ON_GENERATED_VIRTUAL_COLUMN
* support keyread on vcols
* callback into the server to compute vcol values from mi_check/mi_repair
* DMLs just work. Automatically.
* revert part of the db7edfe that moved calculations from
fix_fields to val_str for Item_func_sysconst and descendants
* mark session state dependent functions in check_vcol_func_processor()
* re-run fix_fields for all such functions for every statement
* fix CURRENT_USER/CURRENT_ROLE not to use Name_resolution_context
(that is allocated on the stack in unpack_vcol_info_from_frm())
Note that NOW(), CURDATE(), etc use lazy initialization and do *not*
force fix_fields to be re-run. The rule is:
* lazy initialization is *not* allowed, if it changes metadata (so,
e.g. DAYNAME() cannot use it)
* lazy initialization is *preferrable* if it has side effects (e.g.
NOW() sets thd->time_zone_used=1, so it's better to do it when
the value of NOW is actually needed, not when NOW is simply prepared)
MDEV-10134 Add full support for DEFAULT
- Added support for using tables with MySQL 5.7 virtual fields,
including MySQL 5.7 syntax
- Better error messages also for old cases
- CREATE ... SELECT now also updates timestamp columns
- Blob can now have default values
- Added new system variable "check_constraint_checks", to turn of
CHECK constraint checking if needed.
- Removed some engine independent tests in suite vcol to only test myisam
- Moved some tests from 'include' to 't'. Should some day be done for all tests.
- FRM version increased to 11 if one uses virtual fields or constraints
- Changed to use a bitmap to check if a field has got a value, instead of
setting HAS_EXPLICIT_VALUE bit in field flags
- Expressions can now be up to 65K in total
- Ensure we are not refering to uninitialized fields when handling virtual fields or defaults
- Changed check_vcol_func_processor() to return a bitmap of used types
- Had to change some functions that calculated cached value in fix_fields to do
this in val() or getdate() instead.
- store_now_in_TIME() now takes a THD argument
- fill_record() now updates default values
- Add a lookahead for NOT NULL, to be able to handle DEFAULT 1+1 NOT NULL
- Automatically generate a name for constraints that doesn't have a name
- Added support for ALTER TABLE DROP CONSTRAINT
- Ensure that partition functions register virtual fields used. This fixes
some bugs when using virtual fields in a partitioning function
