PolarDB:Release notes for PolarDB-X data nodes

Category

Description

Fixed issue

The following issue is fixed: Pointer leakage may exist during session attachment and detachment.

The following issue is fixed: When a separated XA transaction is recommitted or rolled back, released transactions may be accessed, resulting in an instance exception.

Category

Description

Optimized feature

The MySQL 8032 code is aligned.

The initialization of the context environment of a request plan is optimized.

Fixed issue

The following issue is fixed: Databases in XRPC occasionally fail to be switched in scenarios that require streaming early stopping.

Category

Description

Optimized feature

The memory ordering of SpinLock SpinRWLock used by XRPC is optimized. This optimization is mainly suitable for CPUs with the weak memory ordering such as ARM processors.

Fixed issue

The sample crash issue is fixed.

The following issue is fixed: Resources such as locks fail to be released when a killed session is not scheduled.

Category

Description

New and optimized feature

The replication and migration feature is supported for physical tables.

The logging feature is optimized for XRPC network-related events by deleting logs concerning TCP and session disconnections.

XRPC code that aligns open-source MySQL 8.0 is optimized.

Fixed issue

The following issue is fixed: The names of auto savepoints are truncated.

Category

Description

Fixed issue

The following issue is fixed: The secondary database fails to be rebuilt due to the leakage of changeset resources.

The following issue is fixed: The configurations of the primary and secondary instances are inconsistent in the production environment when XRPC is enabled to replace the old private protocol.

Category

Description

Fixed issue

The following issue is fixed: XPLAN unexpectedly exits when created columns are queried.

Issues related to foreign key constraints are fixed.

Category

Description

New and optimized feature

The useAffectedRows option can be added to the frontend connection string of the PolarDB-X proprietary protocol.

More character set encodings are available in the PolarDB-X proprietary protocol.

The metadata locks (MDLs) detection mechanism is supported for XRPC.

Fixed issue

The following issue is fixed: The number of affected rows is incorrectly recorded in the audit logs of XPLAN.

The following issue is fixed: The data nodes of the instance fail to exit.

The following issue is fixed: A scheduling latency occurs on the threads of XRPC when a large number of tasks are run.

Issues related to version display are fixed.

Category

Description

New and optimized feature

The CPU affinity of threads can be automatically corrected after XRPC allows the controller to dynamically modify the CPU quota of a storage node.

The auto savepoint feature is supported in XRPC.

The hostname of XRPC is fixed to enhance the detection of THD attach and detach operations.

Fixed issue

The potential THD leak issue is fixed.

The following issue is fixed: Inaccurate numbers of scanned rows and returned rows are displayed in XPLAN audit logs and slow query logs.

The following issue is fixed: Out-of-bound memory accesses may occur when null bitmap is specified for the chunk encoder private protocol.

Category

Description

New feature

XPLAN audit logs and slow query logs can be generated.

The number of XPLAN requests can be taken into account when the number of queries per second (QPS) and the number of executed SELECT statements are calculated.

Fixed issue

The issue that occurs when throttling is implemented based on the number of lines being transmitted is fixed. The throttling mechanism is changed from restricting the traffic of specific proprietary protocols to limiting the number of transmitted bytes.

The following issue is fixed: A crash occurs due to the leakage of a mark in an async commit.

Category

Description

New feature

The proprietary protocol server is rebuilt.

Fixed issue

The following issue is fixed: Inconsistency occurs between single-shard reads and single-shard writes.

The following issue is fixed: Data migration fails when the primary key is of the integer type and contains negative values.

The issue of out-of-memory in Sequence Lex is fixed.

Category

Description

New feature

The xcluster standalone feature is supported.

Category

Description

Fixed issue

The following issue is fixed: No error message is returned if an ultra-large package is sent over the PolarDB-X proprietary protocol.

The following issue is fixed: Excessive logs are generated.

Category

Description

New feature

The change set feature is supported.

Fixed issue

The following issue is fixed: XPLAN exits unexpectedly when a table that has virtual columns is queried.

Category

Description

Fixed issue

The following issue is fixed: Backup operations fail.

The following issue is fixed: PolarDB-X exits unexpectedly due to the array index out of bounds error that is returned when a hint is executed.

Category

Description

Fixed issue

The consistent read in secondary databases for rollback is optimized to ensure that data can be restored from the backup.

Category

Description

Optimized feature

The efficiency of consistent read in secondary databases is optimized.

Fixed issue

The following issue is fixed: Incorrect filtered results are returned because incorrect data is prefetched in MySQL.

Category

Description

New feature

The function that is used to change column types is supported for Online Modify Column.

Fixed issue

The following issue is fixed: An error may be returned for flashback queries after a data node is restarted.

The following issue is fixed: An error occurs when an ALTER TABLE statement in which an ADD COLUMN clause is used and INSTANT is specified as the algorithm is executed.

Category

Description

New features

The flashback query feature is supported.

Category

Description

Fixed issue

The following issue is fixed: The sample feature exits unexpectedly in some scenarios.

The following issue is fixed: An error occurs when m_token is asserted over the PolarDB-X proprietary protocol.

Category

Description

Fixed issue

The following issue is fixed: Read operations and write operations cannot be performed when the thd->get_protocol command is run.

The following issue is fixed: Errors occur during the execution of prepared statements that include sequences of the New Sequence type.

The following issue is fixed: Large files cannot be purged in a quick manner.

The following issue is fixed: Specific characters that are included in JSON-format data cannot be correctly escaped.

The following issue is fixed: The memory leak occurs in schema stats.

Category

Description

New feature

A new sequence engine is supported.

Category

Description

New feature

The port check feature is provided. When a data node starts, the system checks whether the port that is used to send requests over the PolarDB-X proprietary protocol is being used by another process. If the port is being used by another process, the current process automatically exits.

Fixed issue

The following issue is fixed: A crash occurs due to data leaks when chunks are transmitted over a private protocol.

Category

Description

Fixed issue

The following issue is fixed: When a Bloom filter is used, data boundary errors occur if the remainder that is obtained by dividing the length of an element that is calculated by using the xxHash algorithm by 8 is equal to 4.

The following issue is fixed: Compatibility errors occur after the value of innodb_thread_concurrency is changed.

Category

Description

Fixed issue

Redundant rotate events are removed from binary logs.

The following issue is fixed: The previous version of MySQL plug-ins may be used after the storage engine is updated and the deployment script is run to deploy data nodes.

Category

Description

New feature

The xxHash algorithm is supported for Bloom filters.

Raw strings are supported, and the issue in which precision loss occurs for decimal values is fixed in PolarDB-X kernel V5.4.13 and later versions.

The purge sequence feature is provided. The system can automatically increase the value of the lower threshold for data purging to support long-term transactions.

Fixed issue

The following issue is fixed: Faster Checker returns incorrect hash values if Faster Checker does not obtain data.

The following issue is fixed: Data nodes fail when a graceful shutdown is performed for a least recently used (LRU) cache.

The following issue is fixed: Followers can obtain locks.

The following issue is fixed: The corresponding data nodes fail when a graceful shutdown is performed for the Global Timestamp Service (GTS).

The following issue is fixed: Results of de-parameterization for parameters of the bytes type are incorrect.

Category

Description

New feature

The instant add column feature is provided.

The user defined function (UDF) fast hash checker component is provided.

Fixed issue

The following issue is fixed: Token errors occur when requests are sent over the PolarDB-X proprietary protocol.

The following issue is fixed: The network layer may reject requests that are sent over the PolarDB-X proprietary protocol.

Category

Description

New feature

The returning syntax is supported.

A lock-free algorithm is provided for Timestamp Oracle (TSO) to generate timestamps.

Category

Description

Fixed issue

The following issue is fixed: The corresponding data nodes fail when the system performs data sampling.

Category

Description

Optimized feature

Log content is optimized.

Fixed issue

The following issue is fixed: The virtual input and output (VIO) for sessions that are established over the PolarDB-X proprietary protocol fail.

The following issue is fixed: Table leakage occurs when a GTS lease does not exist.

Category

Description

Fixed issue

The following issue is fixed: Sessions that are established over the PolarDB-X proprietary protocol cannot be terminated.

Category

Description

Optimized feature

The process of accessing transactions that are executed on a single shard is optimized.

Fixed issue

The following issue is fixed: TSO returns incorrect results in batch processing mode. The algorithm that is used to distribute timestamps is modified.

Category

Description

Fixed issue

The following issue is fixed: When the PolarDB-X proprietary protocol is used to transmit execution plans to data nodes, the data nodes fail if operations that are not supported by the data nodes are included in execution plans. After this issue is fixed, data nodes report errors and do not fail in this scenario.

Category

Description

New feature

The auto savepoint feature is provided.

The random sampling feature provided by InnoDB is supported.

By default, the polarx_udf plug-in is enabled.

The feedback feature is provided to return the statistics of indexes and the number of rows.

Fixed issue

The following issue is fixed: The transaction sequence leaks over a private protocol.

The following issue is fixed: When the PolarDB-X proprietary protocol is used, the length of decimal values exceeds the upper limit if specific values are specified in double precision scenarios.

The following issue is fixed: Statistics of specific physical data are missing.

The following issue is fixed: The HyperLogLog (HLL) service may exit unexpectedly.

The following issues are fixed: The batch timestamp generation feature of TSO does not take effect, and TSO may generate duplicate timestamps.

The following issue is fixed: The corresponding data nodes fail when utf8mb4 is used as a comparative parameter value in a filter expression that is executed over the PolarDB-X proprietary protocol.

Category

Description

New feature

The cache feature is provided to cache SQL statements and execution plans of SQL queries that are executed over the PolarDB-X proprietary protocol.

The chunk transmission feature is provided to transmit data chunks over the PolarDB-X proprietary protocol.

Fixed issue

The following issue is fixed: The system exits unexpectedly when TSO transactions and DDL operations are performed in parallel.

Category

Description

New feature

The SQL flashback feature is provided.

Fixed issue

The following issue is fixed: Unexpected prepare wait timeout issues occur when specific operations are performed.

The following issue is fixed: Data nodes fail in high concurrency scenarios.

Category

Description

New feature

The dump feature of mysqldump is supported. The system can back up data based on specified snapshot sequences.

Fixed issue

The following issue is fixed: When enable_gts is enabled, binlog events are replayed from the earliest offset after a follower node is restarted.

The following issue is fixed: The leader node of an instance cannot be restored after the leader node is restarted.

By default, the lease period of the GTS is set to 2 seconds.

Commit timestamps (CTSs) can be included in messages that are transmitted over the PolarDB-X proprietary protocol, and the cache feature is provided to cache SQL statements and execution plans of SQL queries.

Category

Description

New feature

TSO timestamps can be transmitted by using messages.

Common transactions can be committed in one-phase commit mode.

Fixed issue

The following issue is fixed: Data nodes fail when the data types of parameters that are returned by UDFs of Bloom filters are incorrect.

The following issue is fixed: Null values and decimal values are not correctly processed by UDFs of Bloom filters.

The following issue is fixed: When CTS transactions are performed based on indexes, the isolation levels of the transactions are changed.

The issue in which an error occurs when one-phase commit transactions are performed is fixed.

Errors that are related to the XA protocol are resolved.

Category

Description

New feature

The CTS persistence feature is provided.

Bloom filters that are created by using UDFs are supported.

UDFs are supported in HLL.

By default, the UDF module polarx_udf.so is loaded.

Optimized feature

The authentication process for requests that are sent over the PolarDB-X proprietary protocol is optimized.

Fixed issue

The following issue is fixed: Assert operations cause data nodes to fail.

Specific content is removed from logs that are recorded when the PolarDB-X proprietary protocol is used.

Category

Description

New feature

A proprietary protocol is provided by PolarDB-X.

The TSO service is supported.

Timestamp-based distributed transactions are supported.

The primary-secondary consistent read feature is provided.

Fixed issue

The following issue is fixed: After a server fails during binlog rotation in an extended architecture (XA) transaction, the XA transaction cannot be restored after the server is restarted.

The following issue is fixed: XA transactions cannot be replayed on follower nodes due to internal locks.

The following issue is fixed: When an XA_PREPARE_EVENT log event is performed, logs are incorrectly replayed and the data that is stored in the disk is incorrect.