between perm and temp tables. Review fixes.
The original bug report complains that if we locked a temporary table
with LOCK TABLES statement, we would not leave LOCK TABLES mode
when this temporary table is dropped.
Additionally, the bug was escalated when it was discovered than
when a temporary transactional table that was previously
locked with LOCK TABLES statement was dropped, futher actions with
this table, such as UNLOCK TABLES, would lead to a crash.
The problem originates from incomplete support of transactional temporary
tables. When we added calls to handler::store_lock()/handler::external_lock()
to operations that work with such tables, we only covered the normal
server code flow and did not cover LOCK TABLES mode.
In LOCK TABLES mode, ::external_lock(LOCK) would sometimes be called without
matching ::external_lock(UNLOCK), e.g. when a transactional temporary table
was dropped. Additionally, this table would be left in the list of LOCKed
TABLES.
The patch aims to address this inadequacy. Now, whenever an instance
of 'handler' is destroyed, we assert that it was priorly
external_lock(UNLOCK)-ed. All the places that violate this assert
were fixed.
This patch introduces no changes in behavior -- the discrepancy in
behavior will be fixed when we start calling ::store_lock()/::external_lock()
for all tables, regardless whether they are transactional or not,
temporary or not.
ORDER BY primary_key on InnoDB table
Queries that use an InnoDB secondary index to retrieve
data don't need to sort in case of ORDER BY primary key
if the secondary index is compared to constant(s).
They can also skip sorting if ORDER BY contains both the
the secondary key parts and the primary key parts (in
that order).
This is because InnoDB returns the rows in order of the
primary key for rows with the same values of the secondary
key columns.
Fixed by preventing temp table sort for the qualifying
queries.
by long running transaction
On Windows opened files can't be deleted. There was a special
upgraded lock mode (TL_WRITE instead of TL_WRITE_ALLOW_READ)
in ALTER TABLE to make sure nobody has the table opened
when deleting the old table in ALTER TABLE. This special mode
was causing ALTER TABLE to hang waiting on a lock inside InnoDB.
This special lock is no longer necessary as the server is
closing the tables it needs to delete in ALTER TABLE.
Fixed by removing the special lock.
Note that this also reverses the fix for bug 17264 that deals with
another consequence of this special lock mode being used.
internal data dictionary
- re-enabled innodb_mysql test;
- added a rule to through away expected warning to mtr_report.pl;
- fixed a test case to produce unique warning.
When a table is being updated it has two set of fields - fields required for
checks of conditions and fields to be updated. A storage engine is allowed
not to retrieve columns marked for update. Due to this fact records can't
be compared to see whether the data has been changed or not. This makes the
server always update records independently of data change.
Now when an auto-updatable timestamp field is present and server sees that
a table handle isn't going to retrieve write-only fields then all of such
fields are marked as to be read to force the handler to retrieve them.
This bug may manifest itself not only with the queries for which
the index-merge access method is chosen. It also may display
itself for queries with DISTINCT.
The bug was in how the Unique::get method used the merge_buffers
function. To compare elements in the the queue employed by
merge_buffers() it must use the buffpek_compare function rather
than the function for binary comparison.
LOCK TABLES takes a list of tables to lock. It may lock several
tables successfully and then encounter a tables that it can't lock,
e.g. because it's locked. In such case it needs to undo the locks on
the already locked tables. And it does that. But it has also notified
the relevant table storage engine handlers that they should lock.
The only reliable way to ensure that the table handlers will give up
their locks is to end the transaction. This is what UNLOCK TABLE
does : it ends the transaction if there were locked tables by LOCK
tables.
It is possible to end the transaction when the lock fails in
LOCK TABLES because LOCK TABLES ends the transaction at its start
already.
Fixed by ending (again) the transaction when LOCK TABLES fails to
lock a table.
(Part of fix for Bug#25621 Error in my_thread_global_end(): 1 threads didn't exit)
Give correct error message if InnoDB table is not found
(This allows us to drop a an innodb table that is not in the InnoDB registery)
wrong result for DML
When making key reference buffers over CHAR fields whitespace (0x20)
must be used to fill in the remaining space in the field's buffer.
This is what Field_string::store() does.
Fixed Field_string::get_key_image() to do the same.
Problem: we may create a deadlock committing changes in the mysql_alter_table() when
LOCK_open is set. Moreover, "in some variants of the ALTER TABLE commit
happens earlier, outside of LOCK_open, in other later - inside. It's no good, a storage
engine code that is called in between could expect a consistency - either there is a
transaction or there is not".
Fix: move the commit to happen earlier and outside of the LOCK_open.
and invalidation in the most general case (non-temporary table and
not simple RENAME or ENABLE/DISABLE KEYS or partitioning command).
See comment for sql/sql_table.cc for more information.
These changes are prerequisite for 5.1 version of fix for bug #23667
"CREATE TABLE LIKE is not isolated from alteration by other connections"
