Problem:
========
There is a possibility that there can be more concurrent DMLs While the
alter table thread is waiting for upgrading to MDL_EXCLUSIVE before commit phase.
In commit phase, InnoDB acquires dict_operation_lock and it already holds MDL_EXCLUSIVE
on the table. After that, InnoDB applies the concurrent DML logs in commit phase.
This could lead to blocking of the following things:
1) DML on the particular table (due to MDL_EXCLUSIVE on the table)
2) InnoDB DDLs (due to dict_operation_lock)
3) Purge thread, stats thread, the master thread (due to dict_operation_lock)
Fix:
====
Apply the concurrent DML logs in commit phase but before acquiring
dict_operation_lock in commit phase. It makes sure that (2), (3) can't be
blocked for longer time.
There was two separate problems:
- Aria pagecache didn't properly handle re-reading of blocks
that have given errors before (this triggered an assert)
- temporary tables that where opened several times where
not properly closed in ALTER, REPAIR or OPTIMIZE table
Other things
- Added a couple of asserts that will make it easier to
find problems like this in the future.
A sequel to 9180e86 and 149b754.
ALTER TABLE ... ADD FOREIGN KEY may crash if parent table is updated
concurrently.
Block FK parent table updates even earlier, before intermediate child
table is created.
Use proper charset info for my_casedn_str() and don't update original
identifiers so that lower_cast_table_names == 2 is honoured.
make live checksum to be returned in handler::info(),
and slow table-scan checksum to be calculated in handler::checksum().
part of
MDEV-16249 CHECKSUM TABLE for a spider table is not parallel and saves all data in memory in the spider head by default
ALTER TABLE ... ADD FOREIGN KEY may trigger assertion failure when
it has LOCK=EXCLUSIVE clause or concurrent FLUSH TABLES is being
executed.
In both cases being altered table is marked as flushed, which forces
subsequent attempt to open parent table to re-open. Which in turn is
not allowed while transaction is running.
Rather than opening parent table, just take appropriate MDL lock.
Also removed table_already_fk_prelocked() check: MDL itself has much
better methods to handle duplicate locks. E.g. the former won't acquire
MDL_SHARED_NO_WRITE if it already has MDL_SHARED_READ.
renaming columns in a CHECK constraint during ALTER TABLE
taints the original TABLE and requires m_need_reopen=1.
In this case, though, renaming was redundant, so just don't do it.
remove TABLE_SHARE::error_table_name() and TABLE_SHARE::orig_table_name
(that was allocated in a wrong memroot in this bug).
instead, simply set TABLE_SHARE::table_name correctly.
Analysis:
========
Increasing the length of the indexed varchar column is not an instant operation for
innodb.
Fix:
===
- Introduce the new handler flag 'Alter_inplace_info::ALTER_COLUMN_INDEX_LENGTH' to
indicate the index length differs due to change of column length changes.
- InnoDB makes the ALTER_COLUMN_INDEX_LENGTH flag as instant operation.
This is a port of Mysql fix.
commit 913071c0b16cc03e703308250d795bc381627e37
Author: Nisha Gopalakrishnan <nisha.gopalakrishnan@oracle.com>
Date: Wed May 30 14:54:46 2018 +0530
BUG#26848813: INDEXED COLUMN CAN'T BE CHANGED FROM VARCHAR(15)
TO VARCHAR(40) INSTANTANEOUSLY
Problem:
========
Server fails to notify the engine by not setting the ADD_PK_INDEX and
DROP_PK_INDEX When there is a
i) Change in candidate for primary key.
ii) New candidate for primary key.
Fix:
====
Server sets the ADD_PK_INDEX and DROP_PK_INDEX while doing alter for the
above problematic case.
The error message modified.
Then the TABLE_SHARE::error_table_name() implementation taken from 10.3,
to be used as a name of the table in this message.
Alter statement changed the THD structure by setting the value to FIELD_CHECK_WARN
and then not resetting it back. This led ANALYZE to throw a warning which previously
it didn't.
