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mariadb/mysql-test/r/mdl_sync.result
Dmitry Lenev eba5d30e67 Implement new type-of-operation-aware metadata locks. 
Add a wait-for graph based deadlock detector to the
MDL subsystem.

Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and
bug #37346 "innodb does not detect deadlock between update and
alter table".

The first bug manifested itself as an unwarranted abort of a
transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER
statement, when this transaction tried to repeat use of a
table, which it has already used in a similar fashion before
ALTER started.

The second bug showed up as a deadlock between table-level
locks and InnoDB row locks, which was "detected" only after
innodb_lock_wait_timeout timeout.

A transaction would start using the table and modify a few
rows.
Then ALTER TABLE would come in, and start copying rows
into a temporary table. Eventually it would stumble on
the modified records and get blocked on a row lock.
The first transaction would try to do more updates, and get
blocked on thr_lock.c lock.
This situation of circular wait would only get resolved
by a timeout.

Both these bugs stemmed from inadequate solutions to the
problem of deadlocks occurring between different
locking subsystems.

In the first case we tried to avoid deadlocks between metadata
locking and table-level locking subsystems, when upgrading shared
metadata lock to exclusive one.
Transactions holding the shared lock on the table and waiting for
some table-level lock used to be aborted too aggressively.

We also allowed ALTER TABLE to start in presence of transactions
that modify the subject table. ALTER TABLE acquires
TL_WRITE_ALLOW_READ lock at start, and that block all writes
against the table (naturally, we don't want any writes to be lost
when switching the old and the new table). TL_WRITE_ALLOW_READ
lock, in turn, would block the started transaction on thr_lock.c
lock, should they do more updates. This, again, lead to the need
to abort such transactions.

The second bug occurred simply because we didn't have any
mechanism to detect deadlocks between the table-level locks
in thr_lock.c and row-level locks in InnoDB, other than
innodb_lock_wait_timeout.

This patch solves both these problems by moving lock conflicts
which are causing these deadlocks into the metadata locking
subsystem, thus making it possible to avoid or detect such
deadlocks inside MDL.

To do this we introduce new type-of-operation-aware metadata
locks, which allow MDL subsystem to know not only the fact that
transaction has used or is going to use some object but also what
kind of operation it has carried out or going to carry out on the
object.

This, along with the addition of a special kind of upgradable
metadata lock, allows ALTER TABLE to wait until all
transactions which has updated the table to go away.
This solves the second issue.
Another special type of upgradable metadata lock is acquired
by LOCK TABLE WRITE. This second lock type allows to solve the
first issue, since abortion of table-level locks in event of
DDL under LOCK TABLES becomes also unnecessary.

Below follows the list of incompatible changes introduced by
this patch:

- From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those
  statements that acquire TL_WRITE_ALLOW_READ lock)
  wait for all transactions which has *updated* the table to
  complete.

- From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE
  (i.e. all statements which acquire TL_WRITE table-level lock) wait
  for all transaction which *updated or read* from the table
  to complete.
  As a consequence, innodb_table_locks=0 option no longer applies
  to LOCK TABLES ... WRITE.

- DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort
  statements or transactions which use tables being dropped or
  renamed, and instead wait for these transactions to complete.

- Since LOCK TABLES WRITE now takes a special metadata lock,
  not compatible with with reads or writes against the subject table
  and transaction-wide, thr_lock.c deadlock avoidance algorithm
  that used to ensure absence of deadlocks between LOCK TABLES
  WRITE and other statements is no longer sufficient, even for
  MyISAM. The wait-for graph based deadlock detector of MDL
  subsystem may sometimes be necessary and is involved. This may
  lead to ER_LOCK_DEADLOCK error produced for multi-statement
  transactions even if these only use MyISAM:

  session 1:         session 2:
  begin;

  update t1 ...      lock table t2 write, t1 write;
                     -- gets a lock on t2, blocks on t1

  update t2 ...
  (ER_LOCK_DEADLOCK)

- Finally,  support of LOW_PRIORITY option for LOCK TABLES ... WRITE
  was abandoned.
  LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same
  priority as the usual LOCK TABLE ... WRITE.
  SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE  in
  the wait queue.

- We do not take upgradable metadata locks on implicitly
  locked tables. So if one has, say, a view v1 that uses
  table t1, and issues:
  LOCK TABLE v1 WRITE;
  FLUSH TABLE t1; -- (or just 'FLUSH TABLES'),
  an error is produced.
  In order to be able to perform DDL on a table under LOCK TABLES,
  the table must be locked explicitly in the LOCK TABLES list.

mysql-test/include/handler.inc:
  Adjusted test case to trigger an execution path on which bug 41110
  "crash with handler command when used concurrently with alter
  table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data
  with alter table" were originally discovered. Left old test case
  which no longer triggers this execution path for the sake of
  coverage.
  Added test coverage for HANDLER SQL statements and type-aware
  metadata locks.
  Added a test for the global shared lock and HANDLER SQL.
  Updated tests to take into account that the old simple deadlock
  detection heuristics was replaced with a graph-based deadlock
  detector.
mysql-test/r/debug_sync.result:
  Updated results (see debug_sync.test).
mysql-test/r/handler_innodb.result:
  Updated results (see handler.inc test).
mysql-test/r/handler_myisam.result:
  Updated results (see handler.inc test).
mysql-test/r/innodb-lock.result:
  Updated results (see innodb-lock.test).
mysql-test/r/innodb_mysql_lock.result:
  Updated results (see innodb_mysql_lock.test).
mysql-test/r/lock.result:
  Updated results (see lock.test).
mysql-test/r/lock_multi.result:
  Updated results (see lock_multi.test).
mysql-test/r/lock_sync.result:
  Updated results (see lock_sync.test).
mysql-test/r/mdl_sync.result:
  Updated results (see mdl_sync.test).
mysql-test/r/sp-threads.result:
  SHOW PROCESSLIST output has changed due to the fact that waiting
  for LOCK TABLES WRITE now happens within metadata locking
  subsystem.
mysql-test/r/truncate_coverage.result:
  Updated results (see truncate_coverage.test).
mysql-test/suite/funcs_1/datadict/processlist_val.inc:
  SELECT FROM I_S.PROCESSLIST output has changed due to fact that
  waiting for LOCK TABLES WRITE now happens within metadata locking
  subsystem.
mysql-test/suite/funcs_1/r/processlist_val_no_prot.result:
  SELECT FROM I_S.PROCESSLIST output has changed due to fact that
  waiting for LOCK TABLES WRITE now happens within metadata locking
  subsystem.
mysql-test/suite/rpl/t/rpl_sp.test:
  Updated to a new SHOW PROCESSLIST state name.
mysql-test/t/debug_sync.test:
  Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter
  no longer allows to trigger execution path involving waiting on
  thr_lock.c lock and therefore reaching debug sync-point covered
  by this test.
mysql-test/t/innodb-lock.test:
  Adjusted test case to the fact that innodb_table_locks=0 option is
  no longer supported, since LOCK TABLES WRITE handles all its
  conflicts within MDL subsystem.
mysql-test/t/innodb_mysql_lock.test:
  Added test for bug #37346 "innodb does not detect deadlock between
  update and alter table".
mysql-test/t/lock.test:
  Added test coverage which checks the fact that we no longer support
  DDL under LOCK TABLES on tables which were locked implicitly.
  Adjusted existing test cases accordingly.
mysql-test/t/lock_multi.test:
  Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary
  deadlock".  Adjusted other test cases to take into account the
  fact that waiting for LOCK TABLES ... WRITE now happens within MDL
  subsystem.
mysql-test/t/lock_sync.test:
  Since LOCK TABLES ... WRITE now takes SNRW metadata lock for
  tables locked explicitly we have to implicitly lock InnoDB tables
  (through view) to trigger the table-level lock conflict between
  TL_WRITE and TL_WRITE_ALLOW_WRITE.
mysql-test/t/mdl_sync.test:
  Added basic test coverage for type-of-operation-aware metadata
  locks. Also covered with tests some use cases involving HANDLER
  statements in which a deadlock could arise.
  Adjusted existing tests to take type-of-operation-aware MDL into
  account.
mysql-test/t/multi_update.test:
  Update to a new SHOW PROCESSLIST state name.
mysql-test/t/truncate_coverage.test:
  Adjusted test case after making LOCK TABLES WRITE to wait until
  transactions that use the table to be locked are completed.
  Updated to the changed name of DEBUG_SYNC point.
sql/handler.cc:
  Global read lock functionality has been
  moved into a class.
sql/lock.cc:
  Global read lock functionality has been
  moved into a class.
  Updated code to use the new MDL API.
sql/mdl.cc:
  Introduced new type-of-operation aware metadata locks.
  To do this:
  - Changed MDL_lock to use one list for waiting requests and one
    list for granted requests. For each list, added a bitmap
    that holds information what lock types a list contains.
    Added a helper class MDL_lock::List to manipulate with granted
    and waited lists while keeping the bitmaps in sync
    with list contents.
  - Changed lock-compatibility functions to use bitmaps that
    define compatibility.
  - Introduced a graph based deadlock detector inspired by
    waiting_threads.c from Maria implementation.
  - Now that we have a deadlock detector, and no longer have
    a global lock to protect individual lock objects, but rather
    use an rw lock per object, removed redundant code for upgrade,
    and the global read lock. Changed the MDL API to
    no longer require the caller to acquire the global
    intention exclusive lock by means of a separate method.
    Removed a few more methods that became redundant.
  - Removed deadlock detection heuristic, it has been made
    obsolete by the deadlock detector.
  - With operation-type-aware metadata locks, MDL subsystem has
    become aware of potential conflicts between DDL and open
    transactions. This made it possible to remove calls to
    mysql_abort_transactions_with_shared_lock() from acquisition
    paths for exclusive lock and lock upgrade. Now we can simply
    wait for these transactions to complete without fear of
    deadlock. Function mysql_lock_abort() has also become
    unnecessary for all conflicting cases except when a DDL
    conflicts with a connection that has an open HANDLER.
sql/mdl.h:
  Introduced new type-of-operation aware metadata locks.
  Introduced a graph based deadlock detector and supporting
  methods.
  Added comments.
  God rid of redundant API calls.
  Renamed m_lt_or_ha_sentinel to m_trans_sentinel,
  since now it guards the global read lock as well as
  LOCK TABLES and HANDLER locks.
sql/mysql_priv.h:
  Moved the global read lock functionality into a
  class.
  Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces
  open_tables() to take MDL_SHARED on tables instead of
  metadata locks specified in the parser. We use this to
  allow PREPARE run concurrently in presence of
  LOCK TABLES ... WRITE.
  Added signature for find_table_for_mdl_ugprade().
sql/set_var.cc:
  Global read lock functionality has been
  moved into a class.
sql/sp_head.cc:
  When creating TABLE_LIST elements for prelocking or
  system tables set the type of request for metadata
  lock according to the operation that will be performed
  on the table.
sql/sql_base.cc:
  - Updated code to use the new MDL API.
  - In order to avoid locks starvation we take upgradable
    locks all at once. As result implicitly locked tables no
    longer get an upgradable lock. Consequently DDL and FLUSH
    TABLES for such tables is prohibited.
    find_write_locked_table() was replaced by
    find_table_for_mdl_upgrade() function.
    open_table() was adjusted to return TABLE instance with
    upgradable ticket when necessary.
  - We no longer wait for all locks on OT_WAIT back off
    action -- only on the lock that caused the wait
    conflict. Moreover, now we distinguish cases when we
    have to wait due to conflict in MDL and old version
    of table in TDC.
  - Upate mysql_notify_threads_having_share_locks()
    to only abort thr_lock.c waits of threads that
    have open HANDLERs, since lock conflicts with only
    these threads now can lead to deadlocks not detectable
    by the MDL deadlock detector.
  - Remove mysql_abort_transactions_with_shared_locks()
    which is no longer needed.
sql/sql_class.cc:
  Global read lock functionality has been moved into a class.
  Re-arranged code in THD::cleanup() to simplify assert.
sql/sql_class.h:
  Introduced class to incapsulate global read lock
  functionality.
  Now sentinel in MDL subsystem guards the global read lock
  as well as LOCK TABLES and HANDLER locks. Adjusted code
  accordingly.
sql/sql_db.cc:
  Global read lock functionality has been moved into a class.
sql/sql_delete.cc:
  We no longer acquire upgradable metadata locks on tables
  which are locked by LOCK TABLES implicitly. As result
  TRUNCATE TABLE is no longer allowed for such tables.
  Updated code to use the new MDL API.
sql/sql_handler.cc:
  Inform MDL_context about presence of open HANDLERs.
  Since HANLDERs break MDL protocol by acquiring table-level
  lock while holding only S metadata lock on a table MDL
  subsystem should take special care about such contexts (Now
  this is the only case when mysql_lock_abort() is used).
sql/sql_parse.cc:
  Global read lock functionality has been moved into a class.
  Do not take upgradable metadata locks when opening tables
  for CREATE TABLE SELECT as it is not necessary and limits
  concurrency.
  When initializing TABLE_LIST objects before adding them
  to the table list set the type of request for metadata lock
  according to the operation that will be performed on the
  table.
  We no longer acquire upgradable metadata locks on tables
  which are locked by LOCK TABLES implicitly. As result FLUSH
  TABLES is no longer allowed for such tables.
sql/sql_prepare.cc:
  Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening
  tables during PREPARE. This allows PREPARE to run
  concurrently in presence of LOCK TABLES ... WRITE.
sql/sql_rename.cc:
  Global read lock functionality has been moved into a class.
sql/sql_show.cc:
  Updated code to use the new MDL API.
sql/sql_table.cc:
  Global read lock functionality has been moved into a class.
  We no longer acquire upgradable metadata locks on tables
  which are locked by LOCK TABLES implicitly. As result DROP
  TABLE is no longer allowed for such tables.
  Updated code to use the new MDL API.
sql/sql_trigger.cc:
  Global read lock functionality has been moved into a class.
  We no longer acquire upgradable metadata locks on tables
  which are locked by LOCK TABLES implicitly. As result
  CREATE/DROP TRIGGER is no longer allowed for such tables.
  Updated code to use the new MDL API.
sql/sql_view.cc:
  Global read lock functionality has been moved into a class.
  Fixed results of wrong merge that led to misuse of GLR API.
  CREATE VIEW statement is not a commit statement.
sql/table.cc:
  When resetting TABLE_LIST objects for PS or SP re-execution
  set the type of request for metadata lock according to the
  operation that will be performed on the table. Do the same
  in auxiliary function initializing metadata lock requests
  in a table list.
sql/table.h:
  When initializing TABLE_LIST objects set the type of request
  for metadata lock according to the operation that will be
  performed on the table.
sql/transaction.cc:
  Global read lock functionality has been moved into a class.
2010-02-01 14:43:06 +03:00

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SET DEBUG_SYNC= 'RESET';
drop table if exists t1,t2,t3;
create table t1 (i int);
create table t2 (i int);
connection: default
lock tables t2 read;
connection: con1
set debug_sync='mdl_upgrade_shared_lock_to_exclusive SIGNAL parked WAIT_FOR go';
alter table t1 rename t3;
connection: default
set debug_sync= 'now WAIT_FOR parked';
connection: con2
set debug_sync='mdl_acquire_lock_wait SIGNAL go';
drop table t1,t2;
connection: con1
connection: default
unlock tables;
connection: con2
ERROR 42S02: Unknown table 't1'
drop table t3;
SET DEBUG_SYNC= 'RESET';
#
# Basic test coverage for type-of-operation aware metadata locks.
#
drop table if exists t1, t2, t3;
set debug_sync= 'RESET';
create table t1 (c1 int);
#
# A) First let us check compatibility rules between differend kinds of
# type-of-operation aware metadata locks.
# Of course, these rules are already covered by the tests scattered
# across the test suite. But it still makes sense to have one place
# which covers all of them.
#
# 1) Acquire S (simple shared) lock on the table (by using HANDLER):
#
handler t1 open;
#
# Switching to connection 'mdl_con1'.
# Check that S, SH, SR and SW locks are compatible with it.
handler t1 open t;
handler t close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
select count(*) from t1;
count(*)
0
insert into t1 values (1), (1);
# Check that SNW lock is compatible with it. To do this use ALTER TABLE
# which will fail after opening the table and thus obtaining SNW metadata
# lock.
alter table t1 add primary key (c1);
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
# Check that SNRW lock is compatible with S lock.
lock table t1 write;
insert into t1 values (1);
unlock tables;
# Check that X lock is incompatible with S lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above RENAME is blocked because of S lock.
#
# Switching to connection 'default'.
# Unblock RENAME TABLE.
handler t1 close;
#
# Switching to connection 'mdl_con1'.
# Reaping RENAME TABLE.
# Restore the original state of the things.
rename table t2 to t1;
#
# Switching to connection 'default'.
handler t1 open;
#
# Switching to connection 'mdl_con1'.
# Check that upgrade from SNW to X is blocked by presence of S lock.
# Sending:
alter table t1 add column c2 int;;
#
# Switching to connection 'mdl_con2'.
# Check that the above ALTER TABLE is blocked because of S lock.
#
# Switching to connection 'default'.
# Unblock ALTER TABLE.
handler t1 close;
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
# Restore the original state of the things.
alter table t1 drop column c2;
#
# Switching to connection 'default'.
handler t1 open;
#
# Switching to connection 'mdl_con1'.
# Check that upgrade from SNRW to X is blocked by presence of S lock.
lock table t1 write;
# Sending:
alter table t1 add column c2 int;;
#
# Switching to connection 'mdl_con2'.
# Check that the above upgrade of SNRW to X in ALTER TABLE is blocked
# because of S lock.
#
# Switching to connection 'default'.
# Unblock ALTER TABLE.
handler t1 close;
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
# Restore the original state of the things.
alter table t1 drop column c2;
unlock tables;
#
# Switching to connection 'default'.
#
# 2) Acquire SH (shared high-priority) lock on the table.
# We have to involve DEBUG_SYNC facility for this as usually
# such kind of locks are short-lived.
#
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
select table_name, table_type, auto_increment, table_comment from information_schema.tables where table_schema='test' and table_name='t1';;
#
# Switching to connection 'mdl_con1'.
set debug_sync= 'now WAIT_FOR locked';
# Check that S, SH, SR and SW locks are compatible with it.
handler t1 open;
handler t1 close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
select count(*) from t1;
count(*)
3
insert into t1 values (1);
# Check that SNW lock is compatible with it. To do this use ALTER TABLE
# which will fail after opening the table and thus obtaining SNW metadata
# lock.
alter table t1 add primary key (c1);
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
# Check that SNRW lock is compatible with SH lock.
lock table t1 write;
delete from t1 limit 1;
unlock tables;
# Check that X lock is incompatible with SH lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above RENAME is blocked because of SH lock.
# Unblock RENAME TABLE.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'default'.
# Reaping SELECT ... FROM I_S.
table_name table_type auto_increment table_comment
t1 BASE TABLE NULL
#
# Switching to connection 'mdl_con1'.
# Reaping RENAME TABLE.
# Restore the original state of the things.
rename table t2 to t1;
#
# Switching to connection 'default'.
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
select table_name, table_type, auto_increment, table_comment from information_schema.tables where table_schema='test' and table_name='t1';;
#
# Switching to connection 'mdl_con1'.
set debug_sync= 'now WAIT_FOR locked';
# Check that upgrade from SNW to X is blocked by presence of SH lock.
# Sending:
alter table t1 add column c2 int;;
#
# Switching to connection 'mdl_con2'.
# Check that the above ALTER TABLE is blocked because of SH lock.
# Unblock RENAME TABLE.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'default'.
# Reaping SELECT ... FROM I_S.
table_name table_type auto_increment table_comment
t1 BASE TABLE NULL
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
# Restore the original state of the things.
alter table t1 drop column c2;
#
# Switching to connection 'default'.
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
select table_name, table_type, auto_increment, table_comment from information_schema.tables where table_schema='test' and table_name='t1';;
#
# Switching to connection 'mdl_con1'.
set debug_sync= 'now WAIT_FOR locked';
# Check that upgrade from SNRW to X is blocked by presence of S lock.
lock table t1 write;
# Sending:
alter table t1 add column c2 int;;
#
# Switching to connection 'mdl_con2'.
# Check that the above upgrade of SNRW to X in ALTER TABLE is blocked
# because of S lock.
# Unblock RENAME TABLE.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'default'.
# Reaping SELECT ... FROM I_S.
table_name table_type auto_increment table_comment
t1 BASE TABLE NULL
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
# Restore the original state of the things.
alter table t1 drop column c2;
unlock tables;
#
# Switching to connection 'default'.
#
#
# 3) Acquire SR lock on the table.
#
#
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Check that S, SH, SR and SW locks are compatible with it.
handler t1 open;
handler t1 close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
select count(*) from t1;
count(*)
3
insert into t1 values (1);
# Check that SNW lock is compatible with it. To do this use ALTER TABLE
# which will fail after opening the table and thus obtaining SNW metadata
# lock.
alter table t1 add primary key (c1);
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
# Check that SNRW lock is not compatible with SR lock.
# Sending:
lock table t1 write;;
#
# Switching to connection 'default'.
# Check that the above LOCK TABLES is blocked because of SR lock.
# Unblock LOCK TABLES.
commit;
#
# Switching to connection 'mdl_con1'.
# Reaping LOCK TABLES.
delete from t1 limit 1;
unlock tables;
#
# Switching to connection 'default'.
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Check that X lock is incompatible with SR lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above RENAME is blocked because of SR lock.
#
# Switching to connection 'default'.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reaping RENAME TABLE.
# Restore the original state of the things.
rename table t2 to t1;
#
# Switching to connection 'default'.
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Check that upgrade from SNW to X is blocked by presence of SR lock.
# Sending:
alter table t1 add column c2 int;;
#
# Switching to connection 'mdl_con2'.
# Check that the above ALTER TABLE is blocked because of SR lock.
#
# Switching to connection 'default'.
# Unblock ALTER TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
# Restore the original state of the things.
alter table t1 drop column c2;
#
# There is no need to check that upgrade from SNRW to X is blocked
# by presence of SR lock because SNRW is incompatible with SR anyway.
#
#
# Switching to connection 'default'.
#
#
# 4) Acquire SW lock on the table.
#
#
begin;
insert into t1 values (1);
#
# Switching to connection 'mdl_con1'.
# Check that S, SH, SR and SW locks are compatible with it.
handler t1 open;
handler t1 close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
select count(*) from t1;
count(*)
4
insert into t1 values (1);
# Check that SNW lock is not compatible with SW lock.
# Again we use ALTER TABLE which fails after opening
# the table to avoid upgrade of SNW -> X.
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'default'.
# Check that the above ALTER TABLE is blocked because of SW lock.
# Unblock ALTER TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'default'.
begin;
insert into t1 values (1);
#
# Switching to connection 'mdl_con1'.
# Check that SNRW lock is not compatible with SW lock.
# Sending:
lock table t1 write;;
#
# Switching to connection 'default'.
# Check that the above LOCK TABLES is blocked because of SW lock.
# Unblock LOCK TABLES.
commit;
#
# Switching to connection 'mdl_con1'.
# Reaping LOCK TABLES.
delete from t1 limit 2;
unlock tables;
#
# Switching to connection 'default'.
begin;
insert into t1 values (1);
#
# Switching to connection 'mdl_con1'.
# Check that X lock is incompatible with SW lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above RENAME is blocked because of SW lock.
#
# Switching to connection 'default'.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reaping RENAME TABLE.
# Restore the original state of the things.
rename table t2 to t1;
#
# There is no need to check that upgrade from SNW/SNRW to X is
# blocked by presence of SW lock because SNW/SNRW is incompatible
# with SW anyway.
#
#
# Switching to connection 'default'.
#
#
# 5) Acquire SNW lock on the table. We have to use DEBUG_SYNC for
# this, to prevent SNW from being immediately upgraded to X.
#
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con1'.
set debug_sync= 'now WAIT_FOR locked';
# Check that S, SH and SR locks are compatible with it.
handler t1 open;
handler t1 close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
select count(*) from t1;
count(*)
5
# Check that SW lock is incompatible with SNW lock.
# Sending:
delete from t1 limit 2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above DELETE is blocked because of SNW lock.
# Unblock ALTER and thus DELETE.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'default'.
# Reaping ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'mdl_con1'.
# Reaping DELETE.
#
# Switching to connection 'default'.
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con1'.
set debug_sync= 'now WAIT_FOR locked';
# Check that SNW lock is incompatible with SNW lock.
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con2'.
# Check that the above ALTER is blocked because of SNW lock.
# Unblock ALTERs.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'default'.
# Reaping first ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'mdl_con1'.
# Reaping another ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'default'.
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con1'.
set debug_sync= 'now WAIT_FOR locked';
# Check that SNRW lock is incompatible with SNW lock.
# Sending:
lock table t1 write;;
#
# Switching to connection 'mdl_con2'.
# Check that the above LOCK TABLES is blocked because of SNW lock.
# Unblock ALTER and thus LOCK TABLES.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'default'.
# Reaping ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'mdl_con1'.
# Reaping LOCK TABLES
insert into t1 values (1);
unlock tables;
#
# Switching to connection 'default'.
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con1'.
set debug_sync= 'now WAIT_FOR locked';
# Check that X lock is incompatible with SNW lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above RENAME is blocked because of SNW lock.
# Unblock ALTER and thus RENAME TABLE.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'default'.
# Reaping ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'mdl_con1'.
# Reaping RENAME TABLE
# Revert back to original state of things.
rename table t2 to t1;
#
# There is no need to check that upgrade from SNW/SNRW to X is
# blocked by presence of another SNW lock because SNW/SNRW is
# incompatible with SNW anyway.
#
# Switching to connection 'default'.
#
#
# 6) Acquire SNRW lock on the table.
#
#
lock table t1 write;
#
# Switching to connection 'mdl_con1'.
# Check that S and SH locks are compatible with it.
handler t1 open;
handler t1 close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
# Check that SR lock is incompatible with SNRW lock.
# Sending:
select count(*) from t1;;
#
# Switching to connection 'default'.
# Check that the above SELECT is blocked because of SNRW lock.
# Unblock SELECT.
unlock tables;
#
# Switching to connection 'mdl_con1'.
# Reaping SELECT.
count(*)
4
#
# Switching to connection 'default'.
lock table t1 write;
#
# Switching to connection 'mdl_con1'.
# Check that SW lock is incompatible with SNRW lock.
# Sending:
delete from t1 limit 1;;
#
# Switching to connection 'default'.
# Check that the above DELETE is blocked because of SNRW lock.
# Unblock DELETE.
unlock tables;
#
# Switching to connection 'mdl_con1'.
# Reaping DELETE.
#
# Switching to connection 'default'.
lock table t1 write;
#
# Switching to connection 'mdl_con1'.
# Check that SNW lock is incompatible with SNRW lock.
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'default'.
# Check that the above ALTER is blocked because of UNWR lock.
# Unblock ALTER.
unlock tables;
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'default'.
lock table t1 write;
#
# Switching to connection 'mdl_con1'.
# Check that SNRW lock is incompatible with SNRW lock.
# Sending:
lock table t1 write;;
#
# Switching to connection 'default'.
# Check that the above LOCK TABLES is blocked because of SNRW lock.
# Unblock waiting LOCK TABLES.
unlock tables;
#
# Switching to connection 'mdl_con1'.
# Reaping LOCK TABLES
insert into t1 values (1);
unlock tables;
#
# Switching to connection 'default'.
lock table t1 write;
#
# Switching to connection 'mdl_con1'.
# Check that X lock is incompatible with SNRW lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'default'.
# Check that the above RENAME is blocked because of SNRW lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'mdl_con1'.
# Reaping RENAME TABLE
# Revert back to original state of things.
rename table t2 to t1;
#
# There is no need to check that upgrade from SNW/SNRW to X is
# blocked by presence of another SNRW lock because SNW/SNRW is
# incompatible with SNRW anyway.
#
# Switching to connection 'default'.
#
#
# 7) Now do the same round of tests for X lock. We use additional
# table to get long-lived lock of this type.
#
create table t2 (c1 int);
#
# Switching to connection 'mdl_con2'.
# Take a lock on t2, so RENAME TABLE t1 TO t2 will get blocked
# after acquiring X lock on t1.
lock tables t2 read;
#
# Switching to connection 'default'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME has acquired X lock on t1 and is waiting for t2.
# Check that S lock in incompatible with X lock.
# Sending:
handler t1 open;;
#
# Switching to connection 'mdl_con2'.
# Check that the above HANDLER statement is blocked because of X lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping HANDLER.
handler t1 close;
#
# Switching to connection 'mdl_con2'.
# Prepare for blocking RENAME TABLE.
lock tables t2 read;
#
# Switching to connection 'default'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME has acquired X lock on t1 and is waiting for t2.
# Check that SH lock in incompatible with X lock.
# Sending:
select column_name from information_schema.columns where table_schema='test' and table_name='t1';;
#
# Switching to connection 'mdl_con2'.
# Check that the above SELECT ... FROM I_S ... statement is blocked
# because of X lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping SELECT ... FROM I_S.
column_name
c1
#
# Switching to connection 'mdl_con2'.
# Prepare for blocking RENAME TABLE.
lock tables t2 read;
#
# Switching to connection 'default'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME has acquired X lock on t1 and is waiting for t2.
# Check that SR lock in incompatible with X lock.
# Sending:
select count(*) from t1;;
#
# Switching to connection 'mdl_con2'.
# Check that the above SELECT statement is blocked
# because of X lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping SELECT.
count(*)
4
#
# Switching to connection 'mdl_con2'.
# Prepare for blocking RENAME TABLE.
lock tables t2 read;
#
# Switching to connection 'default'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME has acquired X lock on t1 and is waiting for t2.
# Check that SW lock in incompatible with X lock.
# Sending:
delete from t1 limit 1;;
#
# Switching to connection 'mdl_con2'.
# Check that the above DELETE statement is blocked
# because of X lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping DELETE.
#
# Switching to connection 'mdl_con2'.
# Prepare for blocking RENAME TABLE.
lock tables t2 read;
#
# Switching to connection 'default'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME has acquired X lock on t1 and is waiting for t2.
# Check that SNW lock is incompatible with X lock.
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con2'.
# Check that the above ALTER statement is blocked
# because of X lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'mdl_con2'.
# Prepare for blocking RENAME TABLE.
lock tables t2 read;
#
# Switching to connection 'default'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME has acquired X lock on t1 and is waiting for t2.
# Check that SNRW lock is incompatible with X lock.
# Sending:
lock table t1 write;;
#
# Switching to connection 'mdl_con2'.
# Check that the above LOCK TABLE statement is blocked
# because of X lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping LOCK TABLE.
unlock tables;
#
# Switching to connection 'mdl_con2'.
# Prepare for blocking RENAME TABLE.
lock tables t2 read;
#
# Switching to connection 'default'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME has acquired X lock on t1 and is waiting for t2.
# Check that X lock is incompatible with X lock.
# Sending:
rename table t1 to t3;;
#
# Switching to connection 'mdl_con2'.
# Check that the above RENAME statement is blocked
# because of X lock.
# Unblock RENAME TABLE
unlock tables;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping RENAME.
rename table t3 to t1;
#
# B) Now let us test compatibility in cases when both locks
# are pending. I.e. let us test rules for priorities between
# different types of metadata locks.
#
#
# Switching to connection 'mdl_con2'.
#
# 1) Check compatibility for pending SNW lock.
#
# Acquire SW lock in order to create pending SNW lock later.
begin;
insert into t1 values (1);
#
# Switching to connection 'default'.
# Add pending SNW lock.
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con1'.
# Check that ALTER TABLE is waiting with pending SNW lock.
# Check that S, SH and SR locks are compatible with pending SNW
handler t1 open t;
handler t close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
select count(*) from t1;
count(*)
4
# Check that SW is incompatible with pending SNW
# Sending:
delete from t1 limit 1;;
#
# Switching to connection 'mdl_con2'.
# Check that the above DELETE is blocked because of pending SNW lock.
# Unblock ALTER TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping ALTER.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'mdl_con1'.
# Reaping DELETE.
#
# We can't do similar check for SNW, SNRW and X locks because
# they will also be blocked by active SW lock.
#
#
# Switching to connection 'mdl_con2'.
#
# 2) Check compatibility for pending SNRW lock.
#
# Acquire SR lock in order to create pending SNRW lock.
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'default'.
# Add pending SNRW lock.
# Sending:
lock table t1 write;;
#
# Switching to connection 'mdl_con1'.
# Check that LOCK TABLE is waiting with pending SNRW lock.
# Check that S and SH locks are compatible with pending SNRW
handler t1 open t;
handler t close;
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
# Check that SR is incompatible with pending SNRW
# Sending:
select count(*) from t1;;
#
# Switching to connection 'mdl_con2'.
# Check that the above SELECT is blocked because of pending SNRW lock.
# Unblock LOCK TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping LOCK TABLE.
unlock tables;
#
# Switching to connection 'mdl_con1'.
# Reaping SELECT.
count(*)
3
# Restore pending SNRW lock.
#
# Switching to connection 'mdl_con2'.
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'default'.
# Sending:
lock table t1 write;;
#
# Switching to connection 'mdl_con1'.
# Check that LOCK TABLE is waiting with pending SNRW lock.
# Check that SW is incompatible with pending SNRW
# Sending:
insert into t1 values (1);;
#
# Switching to connection 'mdl_con2'.
# Check that the above INSERT is blocked because of pending SNRW lock.
# Unblock LOCK TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping LOCK TABLE.
unlock tables;
#
# Switching to connection 'mdl_con1'.
# Reaping INSERT.
# Restore pending SNRW lock.
#
# Switching to connection 'mdl_con2'.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'default'.
# Sending:
lock table t1 write;;
#
# Switching to connection 'mdl_con1'.
# Check that LOCK TABLE is waiting with pending SNRW lock.
# Check that SNW is compatible with pending SNRW
# So ALTER TABLE statements are not starved by LOCK TABLEs.
alter table t1 add primary key (c1);
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'mdl_con2'.
# Unblock LOCK TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping LOCK TABLE.
unlock tables;
#
# We can't do similar check for SNRW and X locks because
# they will also be blocked by active SR lock.
#
#
# Switching to connection 'mdl_con2'.
#
# 3) Check compatibility for pending X lock.
#
# Acquire SR lock in order to create pending X lock.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'default'.
# Add pending X lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME TABLE is waiting with pending X lock.
# Check that SH locks are compatible with pending X
select column_name from information_schema.columns where
table_schema='test' and table_name='t1';
column_name
c1
# Check that S is incompatible with pending X
# Sending:
handler t1 open;;
#
# Switching to connection 'mdl_con2'.
# Check that the above HANDLER OPEN is blocked because of pending X lock.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping HANDLER t1 OPEN.
handler t1 close;
# Restore pending X lock.
#
# Switching to connection 'mdl_con2'.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'default'.
# Add pending X lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME TABLE is waiting with pending X lock.
# Check that SR is incompatible with pending X
# Sending:
select count(*) from t1;;
#
# Switching to connection 'mdl_con2'.
# Check that the above SELECT is blocked because of pending X lock.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping SELECT.
count(*)
4
# Restore pending X lock.
#
# Switching to connection 'mdl_con2'.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'default'.
# Add pending X lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME TABLE is waiting with pending X lock.
# Check that SW is incompatible with pending X
# Sending:
delete from t1 limit 1;;
#
# Switching to connection 'mdl_con2'.
# Check that the above DELETE is blocked because of pending X lock.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping DELETE.
# Restore pending X lock.
#
# Switching to connection 'mdl_con2'.
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'default'.
# Add pending X lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME TABLE is waiting with pending X lock.
# Check that SNW is incompatible with pending X
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'mdl_con2'.
# Check that the above ALTER TABLE is blocked because of pending X lock.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
# Restore pending X lock.
#
# Switching to connection 'mdl_con2'.
handler t1 open;
#
# Switching to connection 'default'.
# Add pending X lock.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'mdl_con1'.
# Check that RENAME TABLE is waiting with pending X lock.
# Check that SNRW is incompatible with pending X
# Sending:
lock table t1 write;;
#
# Switching to connection 'mdl_con3'.
# Check that the above LOCK TABLES is blocked because of pending X lock.
#
# Switching to connection 'mdl_con2'.
# Unblock RENAME TABLE.
handler t1 close;
#
# Switching to connection 'default'.
# Reaping RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'mdl_con1'.
# Reaping LOCK TABLES.
unlock tables;
#
# Switching to connection 'default'.
#
#
# C) Now let us test how type-of-operation locks are handled in
# transactional context. Obviously we are mostly interested
# in conflicting types of locks.
#
#
# 1) Let us check how various locks used within transactional
# context interact with active/pending SNW lock.
#
# We start with case when we are acquiring lock on the table
# which was not used in the transaction before.
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Create an active SNW lock on t2.
# We have to use DEBUG_SYNC facility as otherwise SNW lock
# will be immediately released (or upgraded to X lock).
insert into t2 values (1), (1);
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
alter table t2 add primary key (c1);;
#
# Switching to connection 'default'.
set debug_sync= 'now WAIT_FOR locked';
# SR lock should be acquired without any waiting.
select count(*) from t2;
count(*)
2
commit;
# Now let us check that we will wait in case of SW lock.
begin;
select count(*) from t1;
count(*)
3
# Sending:
insert into t2 values (1);;
#
# Switching to connection 'mdl_con2'.
# Check that the above INSERT is blocked.
# Unblock ALTER TABLE and thus INSERT.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'mdl_con1'.
# Reap ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'default'.
# Reap INSERT.
commit;
#
# Now let us see what happens when we are acquiring lock on the table
# which is already used in transaction.
#
# *) First, case when transaction which has SR lock on the table also
# locked in SNW mode acquires yet another SR lock and then tries
# to acquire SW lock.
begin;
select count(*) from t1;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Create an active SNW lock on t1.
set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'default'.
set debug_sync= 'now WAIT_FOR locked';
# We should still be able to get SR lock without waiting.
select count(*) from t1;
count(*)
3
# Since the above ALTER TABLE is not upgrading SNW lock to X by waiting
# for SW lock we won't create deadlock.
# So the below INSERT should not end-up with ER_LOCK_DEADLOCK error.
# Sending:
insert into t1 values (1);;
#
# Switching to connection 'mdl_con2'.
# Check that the above INSERT is blocked.
# Unblock ALTER TABLE and thus INSERT.
set debug_sync= 'now SIGNAL finish';
#
# Switching to connection 'mdl_con1'.
# Reap ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'default'.
# Reap INSERT.
commit;
#
# **) Now test in which transaction that has SW lock on the table
# against which there is pending SNW lock acquires SR and SW
# locks on this table.
#
begin;
insert into t1 values (1);
#
# Switching to connection 'mdl_con1'.
# Create pending SNW lock on t1.
# Sending:
alter table t1 add primary key (c1);;
#
# Switching to connection 'default'.
# Wait until ALTER TABLE starts waiting for SNW lock.
# We should still be able to get both SW and SR locks without waiting.
select count(*) from t1;
count(*)
5
delete from t1 limit 1;
# Unblock ALTER TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap ALTER TABLE.
ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
#
# Switching to connection 'default'.
#
# 2) Now similar tests for active SNW lock which is being upgraded
# to X lock.
#
# Again we start with case when we are acquiring lock on the
# table which was not used in the transaction before.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con2'.
# Start transaction which will prevent SNW -> X upgrade from
# completing immediately.
begin;
select count(*) from t2;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Create SNW lock pending upgrade to X on t2.
# Sending:
alter table t2 add column c2 int;;
#
# Switching to connection 'default'.
# Wait until ALTER TABLE starts waiting X lock.
# Check that attempt to acquire SR lock on t2 causes waiting.
# Sending:
select count(*) from t2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above SELECT is blocked.
# Unblock ALTER TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap ALTER TABLE.
#
# Switching to connection 'default'.
# Reap SELECT.
count(*)
3
commit;
# Do similar check for SW lock.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con2'.
# Start transaction which will prevent SNW -> X upgrade from
# completing immediately.
begin;
select count(*) from t2;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Create SNW lock pending upgrade to X on t2.
# Sending:
alter table t2 drop column c2;;
#
# Switching to connection 'default'.
# Wait until ALTER TABLE starts waiting X lock.
# Check that attempt to acquire SW lock on t2 causes waiting.
# Sending:
insert into t2 values (1);;
#
# Switching to connection 'mdl_con2'.
# Check that the above INSERT is blocked.
# Unblock ALTER TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap ALTER TABLE.
#
# Switching to connection 'default'.
# Reap INSERT.
commit;
#
# Test for the case in which we are acquiring lock on the table
# which is already used in transaction.
#
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con1'.
# Create SNW lock pending upgrade to X.
# Sending:
alter table t1 add column c2 int;;
#
# Switching to connection 'default'.
# Wait until ALTER TABLE starts waiting X lock.
# Check that transaction is still able to acquire SR lock.
select count(*) from t1;
count(*)
4
# Waiting trying to acquire SW lock will cause deadlock and
# therefore should cause an error.
delete from t1 limit 1;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Unblock ALTER TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap ALTER TABLE.
#
# Switching to connection 'default'.
#
# 3) Check how various locks used within transactional context
# interact with active/pending SNRW lock.
#
# Once again we start with case when we are acquiring lock on
# the table which was not used in the transaction before.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con1'.
lock table t2 write;
#
# Switching to connection 'default'.
# Attempt to acquire SR should be blocked. It should
# not cause errors as it does not creates deadlock.
# Sending:
select count(*) from t2;;
#
# Switching to connection 'mdl_con1'.
# Check that the above SELECT is blocked
# Unblock SELECT.
unlock tables;
#
# Switching to connection 'default'.
# Reap SELECT.
count(*)
4
commit;
# Repeat the same test for SW lock.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con1'.
lock table t2 write;
#
# Switching to connection 'default'.
# Again attempt to acquire SW should be blocked and should
# not cause any errors.
# Sending:
delete from t2 limit 1;;
#
# Switching to connection 'mdl_con1'.
# Check that the above DELETE is blocked
# Unblock DELETE.
unlock tables;
#
# Switching to connection 'default'.
# Reap DELETE.
commit;
#
# Now coverage for the case in which we are acquiring lock on
# the table which is already used in transaction and against
# which there is a pending SNRW lock request.
#
# *) Let us start with case when transaction has only a SR lock.
#
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con1'.
# Sending:
lock table t1 write;;
#
# Switching to connection 'default'.
# Wait until LOCK TABLE is blocked creating pending request for X lock.
# Check that another instance of SR lock is granted without waiting.
select count(*) from t1;
count(*)
4
# Attempt to wait for SW lock will lead to deadlock, thus
# the below statement should end with ER_LOCK_DEADLOCK error.
delete from t1 limit 1;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Unblock LOCK TABLES.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap LOCK TABLES.
unlock tables;
#
# Switching to connection 'default'.
#
# **) Now case when transaction has a SW lock.
#
begin;
delete from t1 limit 1;
#
# Switching to connection 'mdl_con1'.
# Sending:
lock table t1 write;;
#
# Switching to connection 'default'.
# Wait until LOCK TABLE is blocked creating pending request for X lock.
# Check that both SR and SW locks are granted without waiting
# and errors.
select count(*) from t1;
count(*)
3
insert into t1 values (1, 1);
# Unblock LOCK TABLES.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap LOCK TABLES.
unlock tables;
#
# Switching to connection 'default'.
#
# 4) Check how various locks used within transactional context
# interact with active/pending X lock.
#
# As usual we start with case when we are acquiring lock on
# the table which was not used in the transaction before.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con2'.
# Start transaction which will prevent X lock from going away
# immediately.
begin;
select count(*) from t2;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Create pending X lock on t2.
# Sending:
rename table t2 to t3;;
#
# Switching to connection 'default'.
# Wait until RENAME TABLE starts waiting with pending X lock.
# Check that attempt to acquire SR lock on t2 causes waiting.
# Sending:
select count(*) from t2;;
#
# Switching to connection 'mdl_con2'.
# Check that the above SELECT is blocked.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap RENAME TABLE.
#
# Switching to connection 'default'.
# Reap SELECT.
ERROR 42S02: Table 'test.t2' doesn't exist
commit;
rename table t3 to t2;
# The same test for SW lock.
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con2'.
# Start transaction which will prevent X lock from going away
# immediately.
begin;
select count(*) from t2;
count(*)
3
#
# Switching to connection 'mdl_con1'.
# Create pending X lock on t2.
# Sending:
rename table t2 to t3;;
#
# Switching to connection 'default'.
# Wait until RENAME TABLE starts waiting with pending X lock.
# Check that attempt to acquire SW lock on t2 causes waiting.
# Sending:
delete from t2 limit 1;;
#
# Switching to connection 'mdl_con2'.
# Check that the above DELETE is blocked.
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap RENAME TABLE.
#
# Switching to connection 'default'.
# Reap DELETE.
ERROR 42S02: Table 'test.t2' doesn't exist
commit;
rename table t3 to t2;
#
# Coverage for the case in which we are acquiring lock on
# the table which is already used in transaction and against
# which there is a pending X lock request.
#
# *) The first case is when transaction has only a SR lock.
#
begin;
select count(*) from t1;
count(*)
4
#
# Switching to connection 'mdl_con1'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'default'.
# Wait until RENAME TABLE is blocked creating pending request for X lock.
# Check that another instance of SR lock is granted without waiting.
select count(*) from t1;
count(*)
4
# Attempt to wait for SW lock will lead to deadlock, thus
# the below statement should end with ER_LOCK_DEADLOCK error.
delete from t1 limit 1;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'default'.
#
# **) The second case is when transaction has a SW lock.
#
begin;
delete from t1 limit 1;
#
# Switching to connection 'mdl_con1'.
# Sending:
rename table t1 to t2;;
#
# Switching to connection 'default'.
# Wait until RENAME TABLE is blocked creating pending request for X lock.
# Check that both SR and SW locks are granted without waiting
# and errors.
select count(*) from t1;
count(*)
3
insert into t1 values (1, 1);
# Unblock RENAME TABLE.
commit;
#
# Switching to connection 'mdl_con1'.
# Reap RENAME TABLE.
ERROR 42S01: Table 't2' already exists
#
# Switching to connection 'default'.
# Clean-up.
set debug_sync= 'RESET';
drop table t1, t2;
#
# Additional coverage for some scenarios in which not quite
# correct use of S metadata locks by HANDLER statement might
# have caused deadlocks.
#
drop table if exists t1, t2;
create table t1 (i int);
create table t2 (j int);
insert into t1 values (1);
#
# First, check scenario in which we upgrade SNRW lock to X lock
# on a table while having HANDLER READ trying to acquire TL_READ
# on the same table.
#
handler t1 open;
#
# Switching to connection 'handler_con1'.
lock table t1 write;
# Upgrade SNRW to X lock.
# Sending:
alter table t1 add column j int;;
#
# Switching to connection 'handler_con2'.
# Wait until ALTER is blocked during upgrade.
#
# Switching to connection 'default'.
# The below statement should not cause deadlock.
handler t1 read first;;
#
# Switching to connection 'handler_con1'.
# Reap ALTER TABLE.
unlock tables;
#
# Switching to connection 'default'.
# Reap HANDLER READ.
i j
1 NULL
handler t1 close;
#
# Now, check scenario in which upgrade of SNRW lock to X lock
# can be blocked by HANDLER which is open in connection currently
# waiting to get table-lock owned by connection doing upgrade.
#
handler t1 open;
#
# Switching to connection 'handler_con1'.
lock table t1 write, t2 read;
#
# Switching to connection 'default'.
# Execute statement which will be blocked on table-level lock
# owned by connection 'handler_con1'.
# Sending:
insert into t2 values (1);;
#
# Switching to connection 'handler_con1'.
# Wait until INSERT is blocked on table-level lock.
# The below statement should not cause deadlock.
alter table t1 drop column j;
unlock tables;
#
# Switching to connection 'default'.
# Reap INSERT.
handler t1 close;
#
# Then, check the scenario in which upgrade of SNRW lock to X
# lock is blocked by HANDLER which is open in connection currently
# waiting to get SW lock on the same table.
#
handler t1 open;
#
# Switching to connection 'handler_con1'.
lock table t1 write;
#
# Switching to connection 'default'.
# The below insert should be blocked because active SNRW lock on 't1'.
# Sending:
insert into t1 values (1);;
#
# Switching to connection 'handler_con1'.
# Wait until INSERT is blocked because of SNRW lock.
# The below ALTER TABLE will be blocked because of presence of HANDLER.
# Sending:
alter table t1 add column j int;;
#
# Switching to connection 'default'.
# INSERT should be chosen as victim for resolving deadlock.
# Reaping INSERT.
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Close HANDLER to unblock ALTER TABLE.
handler t1 close;
#
# Switching to connection 'handler_con1'.
# Reaping ALTER TABLE.
unlock tables;
#
# Switching to connection 'default'.
#
# Finally, test in which upgrade of SNRW lock to X lock is blocked
# by HANDLER which is open in connection currently waiting to get
# SR lock on the table on which lock is upgraded.
#
handler t1 open;
#
# Switching to connection 'handler_con1'.
lock table t1 write, t2 write;
#
# Switching to connection 'default'.
# The below insert should be blocked because active SNRW lock on 't1'.
# Sending:
insert into t2 values (1);;
#
# Switching to connection 'handler_con1'.
# Wait until INSERT is blocked because of SNRW lock.
# The below ALTER TABLE will be blocked because of presence of HANDLER.
# Sending:
alter table t1 drop column j;;
#
# Switching to connection 'default'.
# INSERT should be chosen as victim for resolving deadlock.
# Reaping INSERT.
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Close HANDLER to unblock ALTER TABLE.
handler t1 close;
#
# Switching to connection 'handler_con1'.
# Reaping ALTER TABLE.
unlock tables;
#
# Switching to connection 'default'.
# Clean-up.
drop tables t1, t2;
#
# Test coverage for basic deadlock detection in metadata
# locking subsystem.
#
drop tables if exists t0, t1, t2, t3, t4, t5;
create table t1 (i int);
create table t2 (j int);
create table t3 (k int);
create table t4 (k int);
#
# Test for the case in which no deadlock occurs.
#
#
# Switching to connection 'deadlock_con1'.
begin;
insert into t1 values (1);
#
# Switching to connection 'deadlock_con2'.
begin;
insert into t2 values (1);
#
# Switching to connection 'default'.
# Send:
rename table t2 to t0, t3 to t2, t0 to t3;;
#
# Switching to connection 'deadlock_con1'.
# Wait until the above RENAME TABLE is blocked because it has to wait
# for 'deadlock_con2' which holds shared metadata lock on 't2'.
# The below statement should wait for exclusive metadata lock
# on 't2' to go away and should not produce ER_LOCK_DEADLOCK
# as no deadlock is possible in this situation.
# Send:
select * from t2;;
#
# Switching to connection 'deadlock_con2'.
# Wait until the above SELECT * FROM t2 is starts waiting
# for an exclusive metadata lock to go away.
#
# Unblock RENAME TABLE by releasing shared metadata lock on t2.
commit;
#
# Switching to connection 'default'.
# Reap RENAME TABLE.
#
# Switching to connection 'deadlock_con1'.
# Reap SELECT.
k
#
# Switching to connection 'default'.
#
# Let us check that in the process of waiting for conflicting lock
# on table 't2' to go away transaction in connection 'deadlock_con1'
# has not released metadata lock on table 't1'.
# Send:
rename table t1 to t0, t3 to t1, t0 to t3;;
#
# Switching to connection 'deadlock_con1'.
# Wait until the above RENAME TABLE is blocked because it has to wait
# for 'deadlock_con1' which should still hold shared metadata lock on
# table 't1'.
# Commit transaction to unblock RENAME TABLE.
commit;
#
# Switching to connection 'default'.
# Reap RENAME TABLE.
#
# Test for case when deadlock occurs and should be detected immediately.
#
#
# Switching to connection 'deadlock_con1'.
begin;
insert into t2 values (2);
#
# Switching to connection 'default'.
# Send:
rename table t2 to t0, t1 to t2, t0 to t1;;
#
# Switching to connection 'deadlock_con1'.
# Wait until the above RENAME TABLE is blocked because it has to wait
# for 'deadlock_con1' which holds shared metadata lock on 't2'.
#
# The below statement should not wait as doing so will cause deadlock.
# Instead it should fail and emit ER_LOCK_DEADLOCK statement.
select * from t1;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
#
# Let us check that failure of the above statement has not released
# metadata lock on table 't1', i.e. that RENAME TABLE is still blocked.
# Commit transaction to unblock RENAME TABLE.
commit;
#
# Switching to connection 'default'.
# Reap RENAME TABLE.
#
# Test for the case in which deadlock also occurs but not immediately.
#
#
# Switching to connection 'deadlock_con1'.
begin;
insert into t2 values (1);
#
# Switching to connection 'default'.
lock table t1 write;
#
# Switching to connection 'deadlock_con1'.
# The below SELECT statement should wait for metadata lock
# on table 't1' and should not produce ER_LOCK_DEADLOCK
# immediately as no deadlock is possible at the moment.
select * from t1;;
#
# Switching to connection 'deadlock_con2'.
# Wait until the above SELECT * FROM t1 is starts waiting
# for an UNRW metadata lock to go away.
# Send RENAME TABLE statement that will deadlock with the
# SELECT statement and thus should abort the latter.
rename table t1 to t0, t2 to t1, t0 to t2;;
#
# Switching to connection 'default'.
# Wait till above RENAME TABLE is blocked while holding
# pending X lock on t1.
# Allow the above RENAME TABLE to acquire lock on t1 and
# create pending lock on t2 thus creating deadlock.
unlock tables;
#
# Switching to connection 'deadlock_con1'.
# Since the latest RENAME TABLE entered in deadlock with SELECT
# statement the latter should be aborted and emit ER_LOCK_DEADLOCK
# error.
# Reap SELECT * FROM t1.
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
#
# Again let us check that failure of the SELECT statement has not
# released metadata lock on table 't2', i.e. that the latest RENAME
# is blocked.
# Commit transaction to unblock this RENAME TABLE.
commit;
#
# Switching to connection 'deadlock_con2'.
# Reap RENAME TABLE ... .
#
# Switching to connection 'default'.
drop tables t1, t2, t3, t4;
#
# Now, test case which shows that deadlock detection empiric
# also takes into account requests for metadata lock upgrade.
#
create table t1 (i int);
insert into t1 values (1);
# Avoid race which occurs when SELECT in 'deadlock_con1' connection
# accesses table before the above INSERT unlocks the table and thus
# its result becomes visible to other connections.
select * from t1;
i
1
#
# Switching to connection 'deadlock_con1'.
begin;
select * from t1;
i
1
#
# Switching to connection 'default'.
# Send:
alter table t1 add column j int, rename to t2;;
#
# Switching to connection 'deadlock_con1'.
# Wait until the above ALTER TABLE ... RENAME acquires exclusive
# metadata lock on 't2' and starts waiting for connection
# 'deadlock_con1' which holds shared lock on 't1'.
# The below statement should not wait as it will cause deadlock.
# An appropriate error should be reported instead.
select * from t2;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Again let us check that failure of the above statement has not
# released all metadata locks in connection 'deadlock_con1' and
# so ALTER TABLE ... RENAME is still blocked.
# Commit transaction to unblock ALTER TABLE ... RENAME.
commit;
#
# Switching to connection 'default'.
# Reap ALTER TABLE ... RENAME.
drop table t2;
#
# Test for bug #46748 "Assertion in MDL_context::wait_for_locks()
# on INSERT + CREATE TRIGGER".
#
drop tables if exists t1, t2, t3, t4, t5;
# Let us simulate scenario in which we open some tables from extended
# part of prelocking set but then encounter conflicting metadata lock,
# so have to back-off and wait for it to go away.
create table t1 (i int);
create table t2 (j int);
create table t3 (k int);
create table t4 (l int);
create trigger t1_bi before insert on t1 for each row
insert into t2 values (new.i);
create trigger t2_bi before insert on t2 for each row
insert into t3 values (new.j);
#
# Switching to connection 'con1root'.
lock tables t4 read;
#
# Switching to connection 'con2root'.
# Send :
rename table t3 to t5, t4 to t3;;
#
# Switching to connection 'default'.
# Wait until the above RENAME TABLE adds pending requests for exclusive
# metadata lock on its tables and blocks due to 't4' being used by LOCK
# TABLES.
# Send :
insert into t1 values (1);;
#
# Switching to connection 'con1root'.
# Wait until INSERT statement waits due to encountering pending
# exclusive metadata lock on 't3'.
unlock tables;
#
# Switching to connection 'con2root'.
# Reap RENAME TABLE.
#
# Switching to connection 'default'.
# Reap INSERT.
# Clean-up.
drop tables t1, t2, t3, t5;
#
# Bug#42546 - Backup: RESTORE fails, thinking it finds an existing table
#
DROP TABLE IF EXISTS t1;
set @save_log_output=@@global.log_output;
set global log_output=file;
#
# Test 1: CREATE TABLE
#
# Connection 2
# Start insert on the not-yet existing table
# Wait after taking the MDL lock
SET DEBUG_SYNC= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
INSERT INTO t1 VALUES(1,"def");
# Connection 1
SET DEBUG_SYNC= 'now WAIT_FOR locked';
# Now INSERT has a MDL on the non-existent table t1.
#
# Continue the INSERT once CREATE waits for exclusive lock
SET DEBUG_SYNC= 'mdl_acquire_lock_wait SIGNAL finish';
# Try to create that table.
CREATE TABLE t1 (c1 INT, c2 VARCHAR(100), KEY(c1));
# Connection 2
# Insert fails
ERROR 42S02: Table 'test.t1' doesn't exist
# Connection 1
SET DEBUG_SYNC= 'RESET';
SHOW TABLES;
Tables_in_test
t1
DROP TABLE IF EXISTS t1;
#
# Test 2: CREATE TABLE LIKE
#
CREATE TABLE t2 (c1 INT, c2 VARCHAR(100), KEY(c1));
# Connection 2
# Start insert on the not-yet existing table
# Wait after taking the MDL
SET DEBUG_SYNC= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish';
INSERT INTO t1 VALUES(1,"def");
# Connection 1
SET DEBUG_SYNC= 'now WAIT_FOR locked';
# Now INSERT has a MDL on the non-existent table t1.
#
# Continue the INSERT once CREATE waits for exclusive lock
SET DEBUG_SYNC= 'mdl_acquire_lock_wait SIGNAL finish';
# Try to create that table.
CREATE TABLE t1 LIKE t2;
# Connection 2
# Insert fails
ERROR 42S02: Table 'test.t1' doesn't exist
# Connection 1
SET DEBUG_SYNC= 'RESET';
SHOW TABLES;
Tables_in_test
t1
t2
DROP TABLE t2;
DROP TABLE IF EXISTS t1;
set global log_output=@save_log_output;
#
# Bug #46044 "MDL deadlock on LOCK TABLE + CREATE TABLE HIGH_PRIORITY
# FOR UPDATE"
#
drop tables if exists t1, t2;
create table t1 (i int);
# Let us check that we won't deadlock if during filling
# of I_S table we encounter conflicting metadata lock
# which owner is in its turn waiting for our connection.
lock tables t1 read;
# Switching to connection 'con46044'.
# Sending:
create table t2 select * from t1 for update;;
# Switching to connection 'default'.
# Waiting until CREATE TABLE ... SELECT ... is blocked.
# First let us check that SHOW FIELDS/DESCRIBE doesn't
# gets blocked and emits and error.
show fields from t2;
ERROR HY000: Table 'test'.'t2' was skipped since its definition is being modified by concurrent DDL statement
# Now test for I_S query which reads only .FRMs.
#
# Query below should only emit a warning.
select column_name from information_schema.columns
where table_schema='test' and table_name='t2';
column_name
Warnings:
Warning 1652 Table 'test'.'t2' was skipped since its definition is being modified by concurrent DDL statement
# Finally, test for I_S query which does full-blown table open.
#
# Query below should not be blocked. Warning message should be
# stored in the 'table_comment' column.
select table_name, table_type, auto_increment, table_comment
from information_schema.tables where table_schema='test' and table_name='t2';
table_name table_type auto_increment table_comment
t2 BASE TABLE NULL Table 'test'.'t2' was skipped since its definition is being modified by concurre
# Switching to connection 'default'.
unlock tables;
# Switching to connection 'con46044'.
# Reaping CREATE TABLE ... SELECT ... .
drop table t2;
#
# Let us also check that queries to I_S wait for conflicting metadata
# locks to go away instead of skipping table with a warning in cases
# when deadlock is not possible. This is a nice thing from compatibility
# and ease of use points of view.
#
# We check same three queries to I_S in this new situation.
# Switching to connection 'con46044_2'.
lock tables t1 read;
# Switching to connection 'con46044'.
# Sending:
create table t2 select * from t1 for update;;
# Switching to connection 'default'.
# Waiting until CREATE TABLE ... SELECT ... is blocked.
# Let us check that SHOW FIELDS/DESCRIBE gets blocked.
# Sending:
show fields from t2;;
# Switching to connection 'con46044_2'.
# Wait until SHOW FIELDS gets blocked.
unlock tables;
# Switching to connection 'con46044'.
# Reaping CREATE TABLE ... SELECT ... .
# Switching to connection 'default'.
# Reaping SHOW FIELDS ...
Field Type Null Key Default Extra
i int(11) YES NULL
drop table t2;
# Switching to connection 'con46044_2'.
lock tables t1 read;
# Switching to connection 'con46044'.
# Sending:
create table t2 select * from t1 for update;;
# Switching to connection 'default'.
# Waiting until CREATE TABLE ... SELECT ... is blocked.
# Check that I_S query which reads only .FRMs gets blocked.
# Sending:
select column_name from information_schema.columns where table_schema='test' and table_name='t2';;
# Switching to connection 'con46044_2'.
# Wait until SELECT COLUMN_NAME FROM I_S.COLUMNS gets blocked.
unlock tables;
# Switching to connection 'con46044'.
# Reaping CREATE TABLE ... SELECT ... .
# Switching to connection 'default'.
# Reaping SELECT COLUMN_NAME FROM I_S.COLUMNS
column_name
i
drop table t2;
# Switching to connection 'con46044_2'.
lock tables t1 read;
# Switching to connection 'con46044'.
# Sending:
create table t2 select * from t1 for update;;
# Switching to connection 'default'.
# Waiting until CREATE TABLE ... SELECT ... is blocked.
# Finally, check that I_S query which does full-blown table open
# also gets blocked.
# Sending:
select table_name, table_type, auto_increment, table_comment from information_schema.tables where table_schema='test' and table_name='t2';;
# Switching to connection 'con46044_2'.
# Wait until SELECT ... FROM I_S.TABLES gets blocked.
unlock tables;
# Switching to connection 'con46044'.
# Reaping CREATE TABLE ... SELECT ... .
# Switching to connection 'default'.
# Reaping SELECT ... FROM I_S.TABLES
table_name table_type auto_increment table_comment
t2 BASE TABLE NULL
drop table t2;
# Switching to connection 'default'.
# Clean-up.
drop table t1;
#
# Test for bug #46273 "MySQL 5.4.4 new MDL: Bug#989 is not fully fixed
# in case of ALTER".
#
drop table if exists t1;
set debug_sync= 'RESET';
create table t1 (c1 int primary key, c2 int, c3 int);
insert into t1 values (1,1,0),(2,2,0),(3,3,0),(4,4,0),(5,5,0);
begin;
select * from t1 where c2 = 3;
c1 c2 c3
3 3 0
#
# Switching to connection 'con46273'.
set debug_sync='after_lock_tables_takes_lock SIGNAL alter_table_locked WAIT_FOR alter_go';
alter table t1 add column e int, rename to t2;;
#
# Switching to connection 'default'.
set debug_sync='now WAIT_FOR alter_table_locked';
set debug_sync='before_open_table_wait_refresh SIGNAL alter_go';
# The below statement should get ER_LOCK_DEADLOCK error
# (i.e. it should not allow ALTER to proceed, and then
# fail due to 't1' changing its name to 't2').
update t1 set c3=c3+1 where c2 = 3;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
#
# Let us check that failure of the above statement has not released
# metadata lock on table 't1', i.e. that ALTER TABLE is still blocked.
# Unblock ALTER TABLE by commiting transaction and thus releasing
# metadata lock on 't1'.
commit;
#
# Switching to connection 'con46273'.
# Reap ALTER TABLE.
#
# Switching to connection 'default'.
# Clean-up.
set debug_sync= 'RESET';
drop table t2;
#
# Test for bug #46673 "Deadlock between FLUSH TABLES WITH READ LOCK
# and DML".
#
drop tables if exists t1;
create table t1 (i int);
# Switching to connection 'con46673'.
begin;
insert into t1 values (1);
# Switching to connection 'default'.
# Statement below should not get blocked. And if after some
# changes to code it is there should not be a deadlock between
# it and transaction from connection 'con46673'.
flush tables with read lock;
unlock tables;
# Switching to connection 'con46673'.
delete from t1 where i = 1;
commit;
# Switching to connection 'default'.
# Clean-up
drop table t1;
#
# Bug#48210 FLUSH TABLES WITH READ LOCK deadlocks
# against concurrent CREATE PROCEDURE
#
# Test 1: CREATE PROCEDURE
# Connection 1
# Start CREATE PROCEDURE and open mysql.proc
SET DEBUG_SYNC= 'after_open_table_mdl_shared SIGNAL table_opened WAIT_FOR grlwait';
CREATE PROCEDURE p1() SELECT 1;
# Connection 2
SET DEBUG_SYNC= 'now WAIT_FOR table_opened';
# Check that FLUSH must wait to get the GRL
# and let CREATE PROCEDURE continue
SET DEBUG_SYNC= 'wait_lock_global_read_lock SIGNAL grlwait';
FLUSH TABLES WITH READ LOCK;
# Connection 1
# Connection 2
UNLOCK TABLES;
# Connection 1
SET DEBUG_SYNC= 'RESET';
# Test 2: DROP PROCEDURE
# Start DROP PROCEDURE and open tables
SET DEBUG_SYNC= 'after_open_table_mdl_shared SIGNAL table_opened WAIT_FOR grlwait';
DROP PROCEDURE p1;
# Connection 2
SET DEBUG_SYNC= 'now WAIT_FOR table_opened';
# Check that FLUSH must wait to get the GRL
# and let DROP PROCEDURE continue
SET DEBUG_SYNC= 'wait_lock_global_read_lock SIGNAL grlwait';
FLUSH TABLES WITH READ LOCK;
# Connection 1
# Connection 2
UNLOCK TABLES;
# Connection 1
SET DEBUG_SYNC= 'RESET';
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