When it comes to DEFAULT values of columns, InnoDB is imposing both
unnecessary and insufficient conditions on whether ALGORITHM=INPLACE
should be allowed for ALTER TABLE.
When changing an existing column to NOT NULL, any NULL values in the
columns only get a special treatment if the column is changed to an
AUTO_INCREMENT column (which is not supported by ALGORITHM=INPLACE)
or the column type is TIMESTAMP. In all other cases, an error
must be reported for the failure to convert a NULL value to NOT NULL.
InnoDB was unnecessarily interested in whether the DEFAULT value
is not constant when altering other than TIMESTAMP columns. Also,
when changing a TIMESTAMP column to NOT NULL, InnoDB was performing
an insufficient check, and it was incorrectly allowing a constant
DEFAULT value while not being able to replace NULL values with that
constant value.
Furthermore, in ADD COLUMN, InnoDB is unnecessarily rejecting certain
nondeterministic DEFAULT expressions (depending on the session
parameters or the current time).
Relaxed assertion (in MySQL it was removed).
For "LOCK TABLES t1 WRITE CONCURRENT, t1 READ" upgrade lock to weakest
existing suitable lock, which is MDL_SHARED_NO_READ_WRITE.
Item_func_sysconst behaves as a non-constant function during prepared
statements and view creation and constant otherwise. Current condition
implied the opposite.
buf_flush_page_cleaner_coordinator(): Signal the thread creator
that the error log output regarding setpriority() has been issued.
innobase_start_or_create_for_mysql(): Wait for
buf_flush_page_cleaner_coordinator() to completely start up.
This prevents sporadic failures of tests that search the server
error log for InnoDB redo log recovery messages.
While the primary purpose of innodb_force_recovery is to allow
data to be rescued from an InnoDB instance that would crash due
to some data corruption, the settings 1, 2, or 3 are relatively
safe to use and there is no need to prevent write transactions
in these modes.
The setting innodb_force_recovery=4 and above can cause database
corruption. For those modes, we already set the flag
high_level_read_only to disable modifications, except DROP TABLE.
MODIFICATIONS_NOT_ALLOWED_MSG_FORCE_RECOVERY: Remove. There is no
need to spam the error log for each refused DML operation. It suffices
to return an error to the client. There will be messages at startup
if innodb_read_only or innodb_force_recovery are preventing writes.
This patch fills in a serious flaw in the
code that supports condition pushdown into
materialized views / derived tables.
If a predicate happened to contain a reference
to a mergeable view / derived table and it does
not depended directly on the target materialized
view / derived table then the predicate was not
considered as a subject to pusdown to this view
/ derived table.
The original intention of the setting innodb_force_recovery=3 was to
disable background activity that could create trouble, most notably,
the rollback of incomplete transactions, and the purge of transaction
history.
MySQL 5.6 introduced more background threads, it is creating
dict_stats_thread and fts_optimize_thread even though these threads
are at least as non-essential as the rollback and purge. These
threads are in fact worse, because they can create new transactions
on their own.
innobase_start_or_create_for_mysql(): Do not create any internal
undo log sources unless innodb_force_recovery<3.
prepare of "fake_select" for union made in JOIN::prepare only if
we do not execute it then before reset, i.e it was for PS prepare
and now required for CREATE VIEW to make global ORDER BY which
belongs to "fake_select" prepared.
MyISAM only allows online alter if autoincrement didn't change.
MyISAM detects that by comparing new autoinc value from create_info,
with the old one, stored in MYI. But in partitioned tables,
create_info->auto_increment_value is for the whole table, max of
autoinc values of individual MYI partitions. So *some* MYI partitions
will inevitably think that alter table changes auto_increment value
and will deny online alter.
Fix: only compare autoinc values, if the user has used AUTO_INCREMENT
in the ALTER TABLE statement.
and
MDEV-13011 Server crashes in THD::handle_condition or Assertion `! is_set() || m_can_overwrite_status' fails upon attempt to connect with max_session_mem_used = 8192
errors when a connection is killed in the
* TABLE_SHARE::init_from_sql_statement_string()
* THD::init()
also, safety-wise, don't check max_mem_used on free() and when some error
was already issued.
buf_flush_init_for_writing(): Reset the FIL_PAGE_TYPE
of the TRX_SYS page to the canonical value
FIL_PAGE_TYPE_TRX_SYS instead of FIL_PAGE_TYPE_UNKNOWN.
Comment from Codership:-
To fix the problem, we changed the certification logic in galera to treat insert
on child table row as exclusive to prevent any operation on referenced
parent table row. At the same time, update and delete on
child table row were demoted to "shared", which makes it possible to
update/delete referenced parent table row, but only in a later transaction.
This change allows somewhat more concurrency for foreign key constrained
transactions, but is still safe for correct certification end result.
When running setup fields during the final step of insert using select
the final setup_fields does not have any sum functions. Our current
condition for calling split_sum_func however would attempt to use an empty
NULL sum_func_list, if the item contained a window function.
The solution is to not perform another split_sum_func for the item
containing a window function if we do not actually have a sum_func_list.
using "show variables", rather than take the value from my.cnf.
"show variables" is more accurate than my.cnf,it also works for parameters
set on the mysqld command line, which is especially important for MTR.
log_calc_max_ages(): Use the requested size in the check, instead of
the detected redo log size. The redo log will be resized at startup
if it differs from what has been requested.
log_calc_max_ages(): Use the requested size in the check, instead of
the detected redo log size. The redo log will be resized at startup
if it differs from what has been requested.
The bug happens because of a combination of unfortunate circumstances:
1. Arguments args[0] and args[2] of Item_func_concat point recursively
(through Item_direct_view_ref's) to the same Item_func_conv_charset.
Both args[0]->args[0]->ref[0] and args[2]->args[0]->ref[0] refer to
this Item_func_conv_charset.
2. When Item_func_concat::args[0]->val_str() is called,
Item_func_conv_charset::val_str() writes its result to
Item_func_conc_charset::tmp_value.
3. Then, for optimization purposes (to avoid copying),
Item_func_substr::val_str() initializes Item_func_substr::tmp_value
to point to the buffer fragment owned by Item_func_conv_charset::tmp_value
Item_func_substr::tmp_value is returned as a result of
Item_func_concat::args[0]->val_str().
4. Due to optimization to avoid memory reallocs,
Item_func_concat::val_str() remembers the result of args[0]->val_str()
in "res" and further uses "res" to collect the return value.
5. When Item_func_concat::args[2]->val_str() is called,
Item_func_conv_charset::tmp_value gets overwritten (see #1),
which effectively overwrites args[0]'s Item_func_substr::tmp_value (see #3),
which effectively overwrites "res" (see #4).
This patch does the following:
a. Changes Item_func_conv_charset::val_str(String *str) to use
tmp_value and str the other way around. After this change tmp_value
is used to store a temporary result, while str is used to return the value.
The fixes the second problem (without SUBSTR):
SELECT CONCAT(t2,'-',t2) c2
FROM (SELECT CONVERT(t USING latin1) t2 FROM t1) sub;
As Item_func_concat::val_str() supplies two different buffers when calling
args[0]->val_str() and args[2]->val_str(), in the new reduction the result
created during args[0]->val_str() does not get overwritten by
args[2]->val_str().
b. Fixing the same problem in val_str() for similar classes
Item_func_to_base64
Item_func_from_base64
Item_func_weight_string
Item_func_hex
Item_func_unhex
Item_func_quote
Item_func_compress
Item_func_uncompress
Item_func_des_encrypt
Item_func_des_decrypt
Item_func_conv_charset
Item_func_reverse
Item_func_soundex
Item_func_aes_encrypt
Item_func_aes_decrypt
Item_func_buffer
c. Fixing Item_func::val_str_from_val_str_ascii() the same way.
Now Item_str_ascii_func::ascii_buff is used for temporary value,
while the parameter passed to val_str() is used to return the result.
This fixes the same problem when conversion (from ASCII to e.g. UCS2)
takes place. See the ctype_ucs.test for example queries that returned
wrong results before the fix.
d. Some Item_func descendand classes had temporary String buffers
(tmp_value and tmp_str), but did not really use them.
Removing these temporary buffers from:
Item_func_decode_histogram
Item_func_format
Item_func_binlog_gtid_pos
Item_func_spatial_collection:
e. Removing Item_func_buffer::tmp_value, because it's not used any more.
f. Renaming Item_func_[un]compress::buffer to "tmp_value",
for consistency with other classes.
Note, this patch does not fix the following classes
(although they have a similar problem):
Item_str_conv
Item_func_make_set
Item_char_typecast
They have a complex implementations and simple swapping between "tmp_value"
and "str" won't work. These classes will be fixed separately.
The option was basically duplicating InnoDB functionality.
Persistent statistics can be accessed via the tables
mysql.innodb_table_stats and mysql.innodb_index_stats.
This is another attempt to fix the bug mdev-12992.
This patch introduces st_select_lex::context_analysis_place for
the place in SELECT where context analysis is currently performed.
It's similar to st_select_lex::parsing_place, but it is used at
the preparation stage.
When the btr_search_latch was split into an array of latches
in MySQL 5.7.8 as part of the Oracle Bug#20985298 fix, the "caching"
of the latch across storage engine API calls was removed, and
the field trx->has_search_latch would only be set during a short
time frame in the execution of row_search_mvcc(), which was
formerly called row_search_for_mysql().
This means that the column
INFORMATION_SCHEMA.INNODB_TRX.TRX_ADAPTIVE_HASH_LATCHED will always
report 0. That column cannot be removed in MariaDB 10.2, but it
can be removed in future releases.
trx_t::has_search_latch: Remove.
trx_assert_no_search_latch(): Remove.
row_sel_try_search_shortcut_for_mysql(): Remove a redundant condition
on trx->has_search_latch (it was always true).
sync_check_iterate(): Make the parameter const.
sync_check_functor_t: Make the operator() const, and remove result()
and the virtual destructor. There is no need to have mutable state
in the functors.
sync_checker<bool>: Replaces dict_sync_check and btrsea_sync_check.
sync_check: Replaces btrsea_sync_check.
dict_sync_check: Instantiated from sync_checker.
sync_allowed_latches: Use std::find() directly on the array.
Remove the std::vector.
TrxInInnoDB::enter(), TrxInInnoDB::exit(): Remove obviously redundant
debug assertions on trx->in_depth, and use equality comparison against 0
because it could be more efficient on some architectures.
