MySQL NDB Cluster 7.3.6 is a new release of NDB Cluster, based on
MySQL Server 5.6 and including features from version 7.3 of the
NDB storage engine, as well as fixing
a number of recently discovered bugs in previous NDB Cluster
Obtaining MySQL NDB Cluster 7.3. MySQL NDB Cluster 7.3 source code and binaries can be obtained from https://dev.mysql.com/downloads/cluster/.
For an overview of changes made in MySQL NDB Cluster 7.3, see What is New in NDB Cluster 7.3.
This release also incorporates all bug fixes and changes made in previous NDB Cluster releases, as well as all bug fixes and feature changes which were added in mainline MySQL 5.6 through MySQL 5.6.19 (see Changes in MySQL 5.6.19 (2014-05-30, General Availability)).
NDB Cluster APIs: Added as an aid to debugging the ability to specify a human-readable name for a given
Ndbobject and later to retrieve it. These operations are implemented, respectively, as the
To make tracing of event handling between a user application and
NDBeasier, you can use the reference (from
getReference()followed by the name (if provided) in printouts; the reference ties together the application
Ndbobject, the event buffer, and the
SUMAblock. (Bug #18419907)
NDB Disk Data: Setting the undo buffer size used by
InitialLogFileGroupto a value greater than that set by
SharedGlobalMemoryprevented data nodes from starting; the data nodes failed with Error 1504 Out of logbuffer memory. While the failure itself is expected behavior, the error message did not provide sufficient information to diagnose the actual source of the problem; now in such cases, a more specific error message Out of logbuffer memory (specify smaller undo_buffer_size or increase SharedGlobalMemory) is supplied. (Bug #11762867, Bug #55515)
NDB Replication: When using
NDB$EPOCH_TRANS, conflicts between
DELETEoperations were handled like conflicts between updates, with the primary rejecting the transaction and dependents, and realigning the secondary. This meant that their behavior with regard to subsequent operations on any affected row or rows depended on whether they were in the same epoch or a different one: within the same epoch, they were considered conflicting events; in different epochs, they were not considered in conflict.
This fix brings the handling of conflicts between deletes by
NDB$EPOCH_TRANSwith that performed when using
NDB$EPOCHfor conflict detection and resolution, and extends testing with
NDB$EPOCH_TRANSto include “delete-delete” conflicts, and encapsulate the expected result, with transactional conflict handling modified so that a conflict between
DELETEoperations alone is not sufficient to cause a transaction to be considered in conflict. (Bug #18459944)
NDB Replication: The implicit
FLUSH LOGSperformed as part of binary log rotation could deadlock and time out with a sufficiently small value for
max_binlog_size. (Bug #18274220, Bug #19895502, Bug #20009154)
References: See also: Bug #18845822, Bug #19793475, Bug #16884594.
NDB Cluster APIs: When two tables had different foreign keys with the same name, ndb_restore considered this a name conflict and failed to restore the schema. As a result of this fix, a slash character (
/) is now expressly disallowed in foreign key names, and the naming format
fk_nameis now enforced by the NDB API. (Bug #18824753)
NDB Cluster APIs: When an
NDBdata node indicates a buffer overflow via an empty epoch, the event buffer places an inconsistent data event in the event queue. When this was consumed, it was not removed from the event queue as expected, causing subsequent
nextEvent()calls to return 0. This caused event consumption to stall because the inconsistency remained flagged forever, while event data accumulated in the queue.
Event data belonging to an empty inconsistent epoch can be found either at the beginning or somewhere in the middle.
pollEvents()returns 0 for the first case. This fix handles the second case: calling
nextEvent()call dequeues the inconsistent event before it returns. In order to benefit from this fix, user applications must call
pollEvents()returns 0. (Bug #18716991)
NDB Cluster APIs: The
pollEvents()method returned 1, even when called with a wait time equal to 0, and there were no events waiting in the queue. Now in such cases it returns 0 as expected. (Bug #18703871)
MySQL NDB ClusterJ: Writing a value failed when read from a fixed-width
utf8to another column of the same type and length but using
latin1. The data was returned with extra spaces after being padded during its insertion. The value is now trimmed before returning it.
This fix also corrects Data length too long errors during the insertion of valid
utf8characters of 2 or more bytes. This was due to padding of the data before encoding it, rather than after. (Bug #71435, Bug #18283369)
Processing a NODE_FAILREP signal that contained an invalid node ID could cause a data node to fail. (Bug #18993037, Bug #73015)
References: This issue is a regression of: Bug #16007980.
When building out of source, some files were written to the source directory instead of the build dir. These included the
manifest.mffiles used for creating ClusterJ jars and the
pom.xmlfile used by
mvn_install_ndbjtie.sh. In addition,
ndbinfo.sqlwas written to the build directory, but marked as output to the source directory in
CMakeLists.txt. (Bug #18889568, Bug #72843)
When the binary log injector thread commits an epoch to the binary log and this causes the log file to reach maximum size, it may need to rotate the binary log. The rotation is not performed until either all the committed transactions from all client threads are flushed to the binary log, or a maximum of 30 seconds has elapsed. In the case where all transactions were committed prior to the 30-second wait, it was possible for committed transactions from multiple client threads to belong to newer epochs than the latest epoch committed by the injector thread, causing the thread to deadlock with itself, and causing an unnecessary 30-second delay before breaking the deadlock. (Bug #18845822)
Adding a foreign key failed with NDB Error 208 if the parent index was parent table's primary key, the primary key was not on the table's initial attributes, and the child table was not empty. (Bug #18825966)
NDBtable served as both the parent table and a child table for 2 different foreign keys having the same name, dropping the foreign key on the child table could cause the foreign key on the parent table to be dropped instead, leading to a situation in which it was impossible to drop the remaining foreign key. This situation can be modelled using the following
CREATE TABLE parent ( id INT NOT NULL, PRIMARY KEY (id) ) ENGINE=NDB; CREATE TABLE child ( id INT NOT NULL, parent_id INT, PRIMARY KEY (id), INDEX par_ind (parent_id), FOREIGN KEY (parent_id) REFERENCES parent(id) ) ENGINE=NDB; CREATE TABLE grandchild ( id INT, parent_id INT, INDEX par_ind (parent_id), FOREIGN KEY (parent_id) REFERENCES child(id) ) ENGINE=NDB;
With the tables created as just shown, the issue occurred when executing the statement
ALTER TABLE child DROP FOREIGN KEY parent_id, because it was possible in some cases for
NDBto drop the foreign key from the
grandchildtable instead. When this happened, any subsequent attempt to drop the foreign key from either the
childor from the
grandchildtable failed. (Bug #18662582)
It was possible for a data node restart to become stuck indefinitely in start phase 101 (see Summary of NDB Cluster Start Phases) when there were connection problems between the node being restarted and one or more subscribing API nodes.
To help prevent this from happening, a new data node configuration parameter
RestartSubscriberConnectTimeouthas been introduced, which can be used to control how long a data node restart can stall in start phase 101 before giving up and attempting to restart again. The default is 12000 ms. (Bug #18599198)
ALTER TABLE ... REORGANIZE PARTITIONafter increasing the number of data nodes in the cluster from 4 to 16 led to a crash of the data nodes. This issue was shown to be a regression caused by previous fix which added a new dump handler using a dump code that was already in use (7019), which caused the command to execute two different handlers with different semantics. The new handler was assigned a new
DUMPcode (7024). (Bug #18550318)
References: This issue is a regression of: Bug #14220269.
Following a long series of inserts, when running with a relatively small redo log and an insufficient large value for
MaxNoOfConcurrentTransactions, there remained transactions that were blocked by the lack of redo log and were thus not aborted in the correct state (waiting for prepare log to be sent to disk, or
LOG_QUEUEDstate). This caused the redo log to remain blocked until unblocked by a completion of a local checkpoint. This could lead to a deadlock, when the blocked aborts in turned blocked global checkpoints, and blocked GCPs block LCPs. To prevent this situation from arising, we now abort immediately when we reach the
LOG_QUEUEDstate in the abort state handler. (Bug #18533982)
ndbmtd supports multiple parallel receiver threads, each of which performs signal reception for a subset of the remote node connections (transporters) with the mapping of remote_nodes to receiver threads decided at node startup. Connection control is managed by the multi-instance
TRPMANblock, which is organized as a proxy and workers, and each receiver thread has a
TRPMANworker running locally.
QMGRblock sends signals to
TRPMANto enable and disable communications with remote nodes. These signals are sent to the
TRPMANproxy, which forwards them to the workers. The workers themselves decide whether to act on signals, based on the set of remote nodes they manage.
The current issue arises because the mechanism used by the
TRPMANworkers for determining which connections they are responsible for was implemented in such a way that each worker thought it was responsible for all connections. This resulted in the
CLOSE_COMREQbeing processed multiple times.
The fix keeps
TRPMANinstances (receiver threads) executing
CLOSE_COMREQrequests. In addition, the correct
TRPMANinstance is now chosen when routing from this instance for a specific remote connection. (Bug #18518037)
During data node failure handling, the transaction coordinator performing takeover gathers all known state information for any failed TC instance transactions, determines whether each transaction has been committed or aborted, and informs any involved API nodes so that they can report this accurately to their clients. The TC instance provides this information by sending
TCKEY_FAILCONFsignals to the API nodes as appropriate top each affected transaction.
In the event that this TC instance does not have a direct connection to the API node, it attempts to deliver the signal by routing it through another data node in the same node group as the failing TC, and sends a
GSN_TCKEY_FAILREFCONF_Rsignal to TC block instance 0 in that data node. A problem arose in the case of multiple transaction cooridnators, when this TC instance did not have a signal handler for such signals, which led it to fail.
This issue has been corrected by adding a handler to the TC proxy block which in such cases forwards the signal to one of the local TC worker instances, which in turn attempts to forward the signal on to the API node. (Bug #18455971)
When running with a very slow main thread, and one or more transaction coordinator threads, on different CPUs, it was possible to encounter a timeout when sending a
DIH_SCAN_GET_NODESREQsignal, which could lead to a crash of the data node. Now in such cases the timeout is avoided. (Bug #18449222)
Failure of multiple nodes while using ndbmtd with multiple TC threads was not handled gracefully under a moderate amount of traffic, which could in some cases lead to an unplanned shutdown of the cluster. (Bug #18069334)
A local checkpoint (LCP) is tracked using a global LCP state (
c_lcpState), and each
NDBtable has a status indicator which indicates the LCP status of that table (
tabLcpStatus). If the global LCP state is
LCP_STATUS_IDLE, then all the tables should have an LCP status of
When an LCP starts, the global LCP status is
LCP_INIT_TABLESand the thread starts setting all the
TLS_ACTIVE. If any tables are not ready for LCP, the LCP initialization procedure continues with
CONTINUEBsignals until all tables have become available and been marked
TLS_ACTIVE. When this initialization is complete, the global LCP status is set to
This bug occurred when the following conditions were met:
An LCP was in the
LCP_INIT_TABLESstate, and some but not all tables had been set to
The master node failed before the global LCP state changed to
LCP_STATUS_ACTIVE; that is, before the LCP could finish processing all tables.
NODE_FAILREPsignal resulting from the node failure was processed before the final
CONTINUEBsignal from the LCP initialization process, so that the node failure was processed while the LCP remained in the
Following master node failure and selection of a new one, the new master queries the remaining nodes with a
MASTER_LCPREQsignal to determine the state of the LCP. At this point, since the LCP status was
LCP_INIT_TABLES, the LCP status was reset to
LCP_STATUS_IDLE. However, the LCP status of the tables was not modified, so there remained tables with
TLS_ACTIVE. Afterwards, the failed node is removed from the LCP. If the LCP status of a given table is
TLS_ACTIVE, there is a check that the global LCP status is not
LCP_STATUS_IDLE; this check failed and caused the data node to fail.
MASTER_LCPREQhandler ensures that the
tabLcpStatusfor all tables is updated to
TLS_COMPLETEDwhen the global LCP status is changed to
LCP_STATUS_IDLE. (Bug #18044717)
When performing a copying
ALTER TABLEoperation, mysqld creates a new copy of the table to be altered. This intermediate table, which is given a name bearing the prefix
#sql-, has an updated schema but contains no data. mysqld then copies the data from the original table to this intermediate table, drops the original table, and finally renames the intermediate table with the name of the original table.
mysqld regards such a table as a temporary table and does not include it in the output from
SHOW TABLES; mysqldump also ignores an intermediate table. However,
NDBsees no difference between such an intermediate table and any other table. This difference in how intermediate tables are viewed by mysqld (and MySQL client programs) and by the
NDBstorage engine can give rise to problems when performing a backup and restore if an intermediate table existed in
NDB, possibly left over from a failed
ALTER TABLEthat used copying. If a schema backup is performed using mysqldump and the mysql client, this table is not included. However, in the case where a data backup was done using the ndb_mgm client's
BACKUPcommand, the intermediate table was included, and was also included by ndb_restore, which then failed due to attempting to load data into a table which was not defined in the backed up schema.
To prevent such failures from occurring, ndb_restore now by default ignores intermediate tables created during
ALTER TABLEoperations (that is, tables whose names begin with the prefix
#sql-). A new option
--exclude-intermediate-sql-tablesis added that makes it possible to override the new behavior. The option's default value is
TRUE; to cause ndb_restore to revert to the old behavior and to attempt to restore intermediate tables, set this option to
FALSE. (Bug #17882305)
The logging of insert failures has been improved. This is intended to help diagnose occasional issues seen when writing to the
mysql.ndb_binlog_indextable. (Bug #17461625)
DEFINERcolumn in the
INFORMATION_SCHEMA.VIEWStable contained erroneous values for views contained in the
ndbinfoinformation database. This could be seen in the result of a query such as
SELECT TABLE_NAME, DEFINER FROM INFORMATION_SCHEMA.VIEWS WHERE TABLE_SCHEMA='ndbinfo'. (Bug #17018500)
CHARcolumn that used the
UTF8character set as a table's primary key column led to node failure when restarting data nodes. Attempting to restore a table with such a primary key also caused ndb_restore to fail. (Bug #16895311, Bug #68893)
-o) option for the ndb_select_all utility worked only when specified as the last option, and did not work with an equals sign.
As part of this fix, the program's
--helpoutput was also aligned with the
--orderoption's correct behavior. (Bug #64426, Bug #16374870)