MySQL NDB Cluster 8.0.17 is a new development release of NDB 8.0,
based on MySQL Server 8.0 and including features in version 8.0 of
NDB storage engine, as well as
fixing recently discovered bugs in previous NDB Cluster releases.
Obtaining NDB Cluster 8.0. NDB Cluster 8.0 source code and binaries can be obtained from https://dev.mysql.com/downloads/cluster/.
For an overview of changes made in NDB Cluster 8.0, see What is New in NDB Cluster.
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 8.0 through MySQL 8.0.17 (see Changes in MySQL 8.0.17 (2019-07-22, General Availability)).
Schema operation timeout detection has been moved from the schema distribution client to the schema distribution coordinator, which now checks ongoing schema operations for timeout at regular intervals, marks participants that have timed out, emits suitable warnings when a schema operation timeout occurs, and prints a list of any ongoing schema operations at regular intervals.
As part of this work, a new option
--ndb-schema-dist-timeoutmakes it possible to set the number of seconds for a given SQL node to wait until a schema operation is marked as having timed out. (Bug #29556148)
Added the status variable
Ndb_trans_hint_count_session, which shows the number of transactions started in the current session that used hints. Compare this with
Ndb_api_trans_start_count_sessionto get the proportion of all
NDBtransactions in the current session that have been able to use hinting. (Bug #29127040)
Important Change: Attempting to drop, using the mysql client, an
NDBtable that existed in the MySQL data dictionary but not in
NDBcaused mysqld to fail with an error. This situation could occur when an
NDBtable was dropped using the ndb_drop_table tool or in an NDB API application using
dropTable(). Now in such cases, mysqld drops the table from the MySQL data dictionary without raising an error. (Bug #29125206)
Important Change: The dependency of ndb_restore on the
NDBTlibrary, which is used for internal testing only, has been removed. This means that the program no longer prints
NDBT_ProgramExit: ...when terminating. Applications that depend upon this behavior should be updated to reflect this change when upgrading to this release.
Packaging: Added debug symbol packages to
.deb-based platforms which do not generate these automatically. (Bug #29040024)
NDB Disk Data: If, for some reason, a disk data table exists in the NDB data dictionary but not in that of the MySQL server, the data dictionary is synchronized by installing the object. This can occur either during the schema synchronization phase when a MySQL server connects to an NDB Cluster, or during table discovery through a DML query or DDL statement.
For disk data tables which used a tablespace for storage, the tablespace ID is stored as part of the data dictionary object, but this was not set during synchronization. (Bug #29597249)
NDB Disk Data: Concurrent Disk Data table and tablespace DDL statements executed on the same SQL node caused a metadata lock deadlock. A DDL statement requires that an exclusive lock be taken on the object being modified and every such lock in turn requires that the global schema lock be acquired in
To fix this issue,
NDBnow tracks when a global schema lock corresponding to an exclusive lock on a tablespace is taken. If a different global schema lock request fails while the first lock, NDB assumes that there is a deadlock. In this case, the deadlock is handled by having the new request release all locks it previously acquired, then retrying them at a later point. (Bug #29394407)
References: See also: Bug #29175268.
NDB Disk Data: Following execution of
ALTER TABLESPACE, SQL statements on an existing table using the affected tablespace failed with error 3508 Dictionary object id (
id) does not exist where the object ID shown refers to the tablespace. Schema distribution of
ALTER TABLESPACEinvolves dropping the old object from the data dictionary on a participating SQL node and creating a new one with a different dictionary object id, but the table object in the SQL node's data dictionary still used the old tablespace ID which rendered it unusable on the participants.
To correct this problem, tables using the tablespace are now retrieved and stored prior to the creation of the new tablespace, and then Updated the new object ID of the tablespace after it has been created in the data dictionary. (Bug #29389168)
NDB Replication: Errors raised from replication settings by a
CREATE TABLEstatement were not properly checked, leading the user to believe (incorrectly) that the table was valid for this purpose. (Bug #29697052)
NDBdid not handle binary logging of virtual generated columns of type
BLOBcorrectly. Now such columns are always regarded as having zero length.
NDB Cluster APIs: The memcached sources included with the NDB distribution would not build with
-Werror=format-security. Now warnings are no longer treated as errors when compiling these files. (Bug #29512411)
NDB Cluster APIs: It was not possible to scan a table whose
SingleUserModeproperty had been set to
SingleUserModeReadOnly. (Bug #29493714)
NDB Cluster APIs: The MGM API
ndb_logevent_get_next2()function did not behave correctly on Windows and 32-bit Linux platforms. (Bug #94917, Bug #29609070)
The version of Python expected by ndb_setup.py was not specified clearly on some platforms. (Bug #29818645)
SharedGlobalMemorywas incorrectly reported as lack of undo buffer memory, even though the cluster used no disk data tables. (Bug #29806771)
References: This issue is a regression of: Bug #92125, Bug #28537319.
TCKEYREQsignals did not always use the expected format when invoked from
TCINDXREQprocessing. (Bug #29772731)
It was possible for an internal
NDB_SCHEMA_OBJECTto be released too early or not at all; in addition, it was possible to create such an object that reused an existing key. (Bug #29759063)
ndb_restore sometimes used
exitHandler()to terminate the program, which could lead to resources not being properly freed. (Bug #29744353)
Improved error message printed when the maximum offset for a
FIXEDcolumn is exceeded. (Bug #29714670)
Communication between the schema distribution client and the schema distribution coordinator is done using
NDB_SCHEMA_OBJECTas well as by writing rows to the
NDB. This allowed for the possibility of a number of different race conditions between when the registration of the schema operation and when the coordinator was notified of it.
This fix addresses the following issues related to the situation just described:
The coordinator failed to abort active schema operations when the binary logging thread was restarted.
Schema operations already registered were not aborted properly.
The distribution client failed to detect correctly when schema distribution was not ready.
The distribution client, when killed, exited without marking the current schema operation as failed.
An operation in
NDB_SHAREcould be accessed without the proper locks being in place.
In addition, usage of the
ndb_schema_shareglobal pointer was removed, and replaced with detecting whether the schema distribution is ready by checking whether an operation for
mysql.ndb_schemahas been created in
NDB_SHARE. (Bug #29639381)
When a backup fails due to
ABORT_BACKUP_ORDbeing received while waiting for buffer space, the backup calls
closeScan()and then sends a
SCAN_FRAGREQsignal to the
DBLQHblock to close the scan. As part of receiving
scanConf()is called on the operation object for the file record which in turn calls
updateWritePtr()on the file system buffer (
FsBuffer). At this point the length sent by
updateWritePtr()should be 0, but in this case was not, which meant that the buffer did not have enough space even though it did not, the problem being that the size is calculated as
scanStop - scanStartand these values were held over since the previous
SCAN_FRAGCONFwas received, and were not reset due to being out of buffer space.
To avoid this problem, we now set
scanStart = scanStopin
scanConfExtra()) which is called as part of processing the
SCAN_FRAGCONF, indirectly by
scanConf()for the backup and first local checkpoint files, and directly for the LCP files which use only the operation record for the data buffer. (Bug #29601253)
The setting for
MaxDMLOperationsPerTransactionwas not validated in a timely fashion, leading to data node failure rather than a management server error in the event that its value exceeded that of
MaxNoOfConcurrentOperations. (Bug #29549572)
Data nodes could fail due to an assert in the
DBTCblock under certain circumstances in resource-constrained environments. (Bug #29528188)
An upgrade to NDB 7.6.9 or later from an earlier version could not be completed successfully if the redo log was filled to more than 25% of capacity. (Bug #29506844)
DBSPJblock called the internal function
lookup_resume()to schedule a previously enqueued operation, it used a correlation ID which could have been produced from its immediate ancestor in the execution order, and not its parent in the query tree as assumed. This could happen during execution of a
NDBchecks whether the execution ancestor is different from the query tree parent, and if not, performs a lookup of the query tree parent, and the parent's correlation ID is enqueued to be executed later. (Bug #29501263)
When a new master took over, sending a
MASTER_LCP_REQsignal and executing
MASTER_LCPCONFfrom participating nodes, it expected that they had not completed the current local checkpoint under the previous master, which need not be true. (Bug #29487340, Bug #29601546)
When selecting a sorted result set from a query that included a
LIMITclause on a single table, and where the sort was executed as
Using filesortand the
refaccess method was used on an ordered index, it was possible for the result set to be missing one or more rows. (Bug #29474188)
ndb_restore tried to extract an 8-character substring of a table name when checking to determine whether or not the table was a blob table, regardless of the length of the name. (Bug #29465794)
When a pushed join was used in combination with the
eq_refaccess method it was possible to obtain an incorrect join result due to the 1 row cache mechanism implemented in NDB 8.0.16 as part of the work done in that version to extend
NDBcondition pushdown by allowing referring values from previous tables. This issue is now fixed by turning off this caching mechanism and reading the row directly from the handler instead, when there is a pushed condition defined on the table. (Bug #29460314)
Improved and made more efficient the conversion of rows by the
ha_ndbclusterhandler from the format used internally by
NDBto that used by the MySQL server for columns that contain neither
BITvalues, which is the most common case. (Bug #29435461)
DROP TABLEcould be attempted an infinite number of times in the event of a temporary error. Now in such cases, the number of retries is limited to 100. (Bug #29355155)
SavedEventobject in the
CMVMIkernel block is written into a circular buffer. Such an object is split in two when wrapping at the end of the buffer;
NDBlooked beyond the end of the buffer instead of in the wrapped data at the buffer's beginning. (Bug #29336793)
NDBdid not compile with
-DWITH_SYSTEM_LIBS=ONdue to an incorrectly configured dependency on
zlib. (Bug #29304517)
Removed clang compiler warnings caused by usage of extra ; characters outside functions; these are incompatible with C++98. (Bug #29227925)
Added support which was missing in ndb_restore for conversions between the following sets of types:
Restore points in backups created with the
SNAPSHOTSTARToption (see Using The NDB Cluster Management Client to Create a Backup) were not always consistent with epoch boundaries. (Bug #27566346)
References: See also: Bug #27497461.
MAX_EXECUTION_TIMEoptimizer hint nor the
max_execution_timesystem variable was respected for DDL statements or queries against
INFORMATION_SCHEMAtables while an
NDBglobal schema lock was in effect. (Bug #27538139)
DDL operations were not always performed correctly on database objects including databases and tables, when multi-byte character sets were used for the names of either or both of these. (Bug #27150334)
ndb_import did not always free up all resources used before exiting. (Bug #27130143)
NDBCLUSTERsubscription log printouts provided only 2 words of the bitmap (in most cases containing 8 words), which made it difficult to diagnose schema distribution issues. (Bug #22180480)
For certain tables with very large rows and a very large primary key,
SNAPSHOTENDwhile performing inserts into one of these tables or
START BACKUP SNAPSHOTSTARTwith concurrent deletes could lead to data node errors.
As part of this fix, ndb_print_backup_file can now read backup files created in very old versions of NDB Cluster (6.3 and earlier); in addition, this utility can now also read undo log files. (Bug #94654, Bug #29485977)
When one of multiple SQL nodes which were connected to the cluster was down and then rejoined the cluster, or a new SQL node joined the cluster, this node did not use the data dictionary correctly, and thus did not always add, alter, or drop databases properly when synchronizing with the existing SQL nodes.
Now, during schema distribution at startup, the SQL node compares all databases on the data nodes with those in its own data dictionary. If any database on the data nodes is found to be missing from the SQL node's data dictionary, the SQL Node installs it locally using
CREATE DATABASE; the database is created using the default MySQL Server database properties currently in effect on this SQL node.