OceanBase Database Enterprise Edition V4.2.1|V4.2.2| docs|Distributed Database

OceanBase Database Enterprise Edition V4.2.1

Last Updated：2024-03-05 01:54:26 Updated

Version information

Release date: September 28, 2023
Version: V4.2.1 GA
RPM version: oceanbase-4.2.1.0-100000182023092722

Overview

OceanBase Database V4.2.1 is the first long-term support (LTS) version in the V4.2.x series. This version introduced new features compatible with MySQL, such as the VALUES statement and JSON_TABLE expression. It also provides compatibility with Oracle through features like DBLink for package calling and sequence reading. Additionally, this version introduced the Workload Repository (WR)-based data collection framework and enhanced end-to-end diagnostic capabilities for commercialization. It optimized system resource utilization and supports table-level restore and Tencent Cloud Object Storage (COS). This version is recommended in production environments for routine business operations both in the cloud and offline.

Key features

Compatibility with MySQL

VALUES statement

The VALUES statement was introduced in MySQL 8.0.19. It can be used to quickly construct a table of data or as a standalone DML statement with support for ORDER BY and Limit clauses. It can also be used as a special table in regular DML statements. OceanBase Database V4.2.1 is compatible with MySQL Database and supports the VALUES statement, making table value construction more convenient and easy to use. For more information, see VALUES.
RENAME COLUMN

The RENAME COLUMN syntax was supported since MySQL 8.0. It allows users to rename columns without changing their definitions, which is more lightweight than the CHANGE COLUMN syntax. OceanBase Database is compatible with the RENAME COLUMN syntax of MySQL 8.0 since V4.2.1. For more information, see RENAME COLUMN.

Compatibility with Oracle

Extended DBLink capabilities

In OceanBase Database V4.1.0, the Oracle mode already supported the ability to read and write native Oracle tables through DBLink. Starting from V4.2.1, it also supports reading remote packages through DBLink. After you establish a connection with Oracle Database, you can call remote stored procedures by using a string in the format of remote stored procedure name @DBLink name in the Oracle tenant of OceanBase Database. You can also call a stored procedure by using remote synonyms defined in the remote database or local synonyms defined in DBLink. For more information, see PL DBLink.

In addition, OceanBase Database V4.2.1 supports access to remote SEQUENCE objects. Similar to data tables, you can access remote SEQUENCE objects, including calculating the NEXTVAL and CURRVAL values of SEQUENCE objects, by using a string in the format of SEQUENCE object name @DBLink name.
Partition or subpartition renaming

Oracle Database supports the RENAME PARTITION and RENAME SUBPARTITION syntax for renaming a partition or subpartition. OceanBase Database has supported partitioned and subpartitioned tables since its early versions but lacked a simple method to change partition names. Starting from V4.2.1, OceanBase Database is compatible with the RENAME PARTITION and RENAME SUBPARTITION syntax of Oracle Database, making it easier to rename partitions or subpartitions. For more information, see Rename a partition or subpartition.

OBKV features

JSON_TABLE expression

JSON is a semi-structured data format where users can extract specific values from JSON strings based on a path. The JSON_TABLE expression allows users to convert semi-structured data into structured data. The earlier versions of OceanBase Database already supported the JSON data type in both MySQL mode and Oracle mode, but the JSON_TABLE expression was not implemented in MySQL mode. To meet the needs of users who want to convert JSON data into structured data for computations, OceanBase Database V4.2.1 also supports this expression in MySQL mode. For more information, see JSON_TABLE.
OBKV TTL

Time-to-live (TTL) is a commonly used feature in NoSQL databases, designed to automatically expire data. For example, in businesses that deal with historical data, there is a need to periodically scan the data, determine its expiration time, and delete it accordingly. Many businesses currently rely on the TableAPI of OBKV. To simplify the management of periodic data, OceanBase Database provided the OBKV TTL capability since V4.2.1. Users can define TTL attributes at the table or row level using the CREATE TABLE statement so that expired data is not processed during read and write operations in OBKV. For more information, see TTL.

Performance improvements

Concurrent execution of CREATE TABLE

In the earlier versions of OceanBase Database, DDL requests were executed serially in RootService queues. Starting from OceanBase Database V4.1.0, the concurrent DDL capability was introduced, with support for concurrent execution of TRUNCATE TABLE. To address the performance issues related to schema migration for tables with millions of data rows, V4.2.1 now supports concurrent execution of CREATE TABLE, providing a performance improvement of tenfold or even more compared with serial execution.
Improved foreign key check performance

Prior to OceanBase Database V4.2.1, foreign key checks were implemented using nested SQL statements, incurring significant overhead. From V4.2.1, foreign key checks are performed using Database Autonomy Service (DAS) tasks, and batch checks in single-table DML operations is supported. Additionally, with the check result caching strategy, noticeable performance improvements have been achieved in INSERT and UPDATE scenarios. In a single-node scenario (where the parent table and child table are on the same node), the performance degradation caused by foreign key checks during INSERT and UPDATE operations on foreign key tables is generally controlled to around 10% compared with tables without foreign keys. In a distributed scenario (where the parent table and child table are on different nodes), the performance degradation is generally controlled to around 30% compared with tables without foreign keys during INSERT and UPDATE operations.
Dynamic sampling on MemTables

OceanBase Database V4.2.0 introduced the dynamic sampling feature, which samples data during the generation of an execution plan. When the number of rows in the SSTable exceeds that in the MemTable, dynamic sampling is performed on SSTable blocks. When the number of rows in the MemTable exceeds that in the SSTable, dynamic sampling is performed on the MemTable. In V4.2.0, this was achieved through full read of the MemTable, which was relatively inefficient. However, in V4.2.1, direct sampling for the MemTable is implemented, utilizing RANGE partitioning to perform interval reads. This enhancement significantly improves the efficiency of dynamic sampling on the MemTable.
Parallel read of archived logs

In OceanBase Database V4.1.0, OceanBase Change Data Capture (CDC) can read archived logs through the CDC service or directly read logs from the archive destination. In V4.2.0, a network-based standby database reuses the log pulling framework of OceanBase CDC to pull logs from the primary database by using the CDC service. After the CDC service receives a log pulling remote procedure call (RPC) request from OceanBase CDC or a network-based standby database, the service first attempts to read logs from the local disk. If the corresponding logs do not exist in the local disk due to reasons such as log stream garbage collection (GC) or log recycling, and if the tenant has enabled log archiving, the CDC service reads logs from the log archive destination, such as the network file system (NFS) or Alibaba Cloud Object Storage Service (OSS). The log reading performance of the CDC service determines the log consumption speed at the downstream. If the performance of the CDC service in reading archived logs from OSS is poor, the synchronization link or the network-based standby database may lag behind the primary database and may be unable to become synchronized with the primary database. To address this issue, V4.2.1 allows the CDC service to read OSS-archived log files based on the basic capability of parallel read of OSS files.

Resource optimization

This version optimized the utilization of system resources in public cloud environments, including user tenant memory, memory of the SYS500 tenant, and operating system memory. For example, for Elastic Compute Service (ECS) instances with specifications of 128 GB or higher, the memory utilization of system resources has been reduced from around 30% to approximately 15%.

High availability enhancement

Table-level restore

Prior to OceanBase Database V4.2.1, tenant-level data restore was supported. If data within a table was damaged due to a misoperation, users needed to rely on the physical restore feature to restore the tenant to a previous point in time or use the import/export feature for table-level restore. V4.2.1 added support for table-level restore, allowing users to specify which backup data to use, which databases or tables to restore, which tenant to operate on, and the desired recovery point in time on the target cluster. For more information, see Table-level restore.
Support for COS

OceanBase Database V4.1.0 supports OSS as the backup media. OceanBase Database V4.2.1 supplements this support by allowing users to back up logs and data to COS and read backup data from COS for data restore.

Security enhancement

Data integrity protection: The Security Assessment of Commercial Cryptography Application imposes requirements for confidentiality and integrity protection on stored data in information systems. In the versions earlier than V4.2.1, the transparent encryption feature of OceanBase Database has already supported AES_ECD and SM4_CBC (which are named in the format of encryption algorithm_encryption mode), providing confidentiality protection for stored data. V4.2.1 added support for the GCM mode. In addition to data encryption, the checksum of ciphertext is calculated based on the key, and the ciphertext is checked during decryption to determine whether the ciphertext has been changed, thereby protecting data integrity.

Diagnostic capabilities improvement

WR-based data collection framework

The ease of use of the database performance diagnostics feature is closely related to the efficiency of system tuning. Oracle Database 10g introduces proactive automatic diagnostic capabilities such as Active Session History (ASH), Automatic Workload Repository (AWR), and Automatic Database Diagnostic Monitor (ADDM), and provides an inside-out (with information collected by internal components) and top-down (based on the database time and other metrics) database optimization and analysis framework. After decades of development, these capabilities have become industry benchmarks. OceanBase Database V4.2.1 implements a data collection framework similar to AWR of Oracle Database. The framework collects existing data such as ASH reports, statistics, wait events, and SQL execution details, and periodically persists performance-related views of OceanBase Database. OceanBase Database V4.2.1 introduces WR views and supports configuration adjustment and snapshot management by using DBMS_WORKLOAD_REPOSITORY packages. The new version also unifies, streamlines, enriches, and enhances SYSSTAT, ASH, and other statistical metrics for higher comprehensiveness and accuracy. The performance diagnostic capabilities will be further enhanced in future OceanBase Database versions. For more information, see Overview of WR.
Enhanced ASH feature

The ASH feature was introduced in OceanBase Database V4.0.0_CE. It samples the status of all active sessions in the system at an interval of 1 second and records the information in internal tables. In OceanBase Database V4.2.1, additional sampling points related to transactions, storage, and DAS were added. The ASH data is collected into the WR internal table at a default sampling rate of 10:1 and a collection interval of 1 hour. By analyzing ASH data, you can easily identify issues such as long wait events, slow SQL statements, and resource utilization of active sessions, which helps in performance optimization.
End-to-end diagnostics feature

OceanBase Database V4.2.0 supports visualized end-to-end tracing of SQL requests, and in V4.2.1, the configuration management capability for end-to-end diagnosis is further enhanced. A new view GV$OB_FLT_TRACE_CONFIG is added to record the configuration policies for end-to-end diagnostics at different levels. The GV$OB_PROCESSLIST view now includes LEVEL, SAMPLE_PERCENTAGE, and RECORD_POLICY columns to display the monitoring level, sampling frequency, and recording/printing policy that are effective for each session. Additionally, the GV$OB_SQL_AUDIT view includes a new column FLT_TRACE_ID to record the end-to-end trace information, enabling comprehensive SQL tracing. OceanBase Cloud Platform (OCP) will also provide corresponding page functionality to support this feature.

Product form

Public cloud primary address mode: In the public cloud architecture, the Client -> SLB -> ODP -> OceanBase Database link can be too long, resulting in significant performance loss in scenarios that require extremely high performance. For businesses whose data is stored on a single node and does not require read/write splitting, OceanBase Database V4.2.1 provides the primary address mode where a client can directly connect to a database through Alibaba Cloud Server Load Balancer (SLB), greatly reducing performance loss in the link.

Product behavioral changes

The following table describes the product behavioral changes made in this version.

Feature	Change description
Triggers disabled for the `LOAD DATA` statement	The `LOAD DATA` statement is executed in parallel for fast data import. When parallel execution involves triggers, trigger correctness issues may occur. Therefore, triggers are disabled for the `LOAD DATA` statement in OceanBase Database V4.2.1.
Semantic change for `tenant=all`	In the versions earlier than OceanBase Database V4.2.1, the semantics of `tenant=all` was ambiguous. For example, `tenant=all` indicates all tenants in system parameter settings, but indicates user tenants in backup and restore settings. Since OceanBase Database V4.2.1, the semantics of `tenant=all` is changed and specifies "to include only all user tenants and to exclude SYS and META tenants". `tenant=all_user` and `tenant=all_meta` are added, which respectively indicate all user tenants and all META tenants. After the change, `tenant=all` and `tenant=all_user` share the exact same semantics. Therefore, `tenant=all` will be deprecated in future versions.
Load balancing control	OceanBase Database V4.2.0 introduced the load balancing and transfer capabilities, which are specified by the tenant-level parameter `enable_rebalance`. However, when the `enable_rebalance` parameter is disabled, you cannot modify `unit_num`, `primary_zone`, and other parameters in O&M commands. OceanBase Database V4.2.1 introduced the tenant-level parameter `enable_transfer`, which allows you to disable the transfer feature for a tenant. You can use it with the `enable_rebalance` parameter to control the load balancing strategy for a tenant. `enable_rebalance=true` and `enable_transfer=true`: specify to dynamically adjust the number of log streams for a tenant based on the load balancing algorithm and automatically perform leader balancing and partition balancing for the tenant. `enable_rebalance=true` and `enable_transfer=false`: specify not to dynamically adjust the number of log streams or perform transfer but only to perform log stream balancing based on existing log streams. `enable_rebalance=false` and `enable_transfer`: invalid. In this case, no load balancing related O&M commands are allowed.
Case sensitivity in OceanBase CDC	OceanBase CDC is case-insensitive in versions earlier than V4.2.1. The new version supports case sensitivity. The specific behaviors are as follows: For MySQL tenants, the database and table names are output according to the setting of the `lower_case_table_names` parameter, whose valid values are `0`, `1`, and `2`. For Oracle tenants, the original database and table names are output. You can use double quotation marks (") to control the case.
Transport Layer Security (TLS) protocol version for SSL encryption	In the versions earlier than V4.2.1, there were no restrictions on the TLS protocol version for SSL encryption. Therefore, clients can use the TLS protocol of an early version for encrypted communication with databases. However, some scenarios require TLS1.2 and TLS1.3 for higher security. For compatibility with clients of earlier versions, OceanBase Database V4.2.1 introduces the `sql_protocol_min_tls_version` parameter, which allows you to specify the minimum version of the TLS protocol. The default value is compatible with previous versions.
Calling a stored procedure with an output parameter without returning a result set	MySQL allows you to call a stored procedure with an output parameter without returning the result set of the output parameter. In the versions earlier than OceanBase Database V4.2.1, a result set of an output parameter is returned, causing the native MySQL driver to report an error. In OceanBase Database V4.2.1, after you execute a `CALL` statement by using OBClient, the result set of the output parameter is no longer displayed.
zlib compression disabled	In OceanBase Database V4.2.1, you cannot use `zlib` compression for new tables or change the compression algorithm of an existing table to `zlib`.

View changes

The following table describes the changes to views made in this version.

View	Change type	Description
DBA/USER/ALL_CONSTRAINTS	Modified	In previous versions, the `DBA/USER/ALL_CONSTRAINTS` view contains the `GENERATED` column, which is defined as `cast("NULL" as VARCHAR2(14))`. In this version, the column is defined to output `GENERATED NAME` or `USER NAME` for compatibility with Oracle. However, if you upgrade an earlier version to this version, existing `NULL` values in this column will be retained.
CDB/DBA_WR_CONTROL	New	Stores WR-related configurations.
[G]V$OB_PROCESSLIST	Modified	The `LEVEL`, `SAMPLE_PERCENTAGE`, and `RECORD_POLICY` columns are added to display the monitoring level, sampling frequency, and recording/printing strategy that take effect on a session. The `LB_VID`, `LB_VIP`, `LB_VPORT`, `IN_BYTES`, and `OUT_BYTES` columns are added to meet statistics requirements in public cloud primary address mode.
[G]V$OB_TENANT_RUNTIME_INFO	New	Displays the running details of tenants.
DBA_SCHEDULER_JOB_RUN_DETAILS	New	Displays the running status of scheduled tasks under Oracle tenants.
[G]V$OB_SQL_AUDIT	Modified	The `FLT_TRACE_ID` column is added to record end-to-end trace information.

Parameter changes

The following table describes the parameter changes made in this version.

Parameter	Change type	Description
memory_limit_percentage	Modified	The upper limit of the percentage of available memory for OBServer nodes is changed from 90% to 95%. OBServer nodes are allowed to use a higher percentage of resources in servers with high specifications.
sql_protocol_min_tls_version	New	The minimum version of the SSL/TLS protocol used by SSL connections for SQL statements. This is a cluster-level parameter. The default value is `none`, which means there are no restrictions on the TLS version for connections. Note This parameter controls only the version number of SSL. To enable SSL, you must set the `ssl_client_authentication` parameter.
enable_transfer	New	Specifies whether to allow transfer within the tenant. This is a tenant-level parameter. This parameter is invalid when `enable_rebalance` is disabled. The default value is `True`, which indicates that transfer within the tenant is allowed.
compaction_dag_cnt_limit	New	The maximum number of directed acyclic graphs (DAGs) in a compaction DAG queue. This parameter is a tenant-level parameter. The default value is `15000`. In scenarios with millions of partitions, you can increase the value of this parameter to speed up compaction, which however increases memory consumption.
compaction_schedule_tablet_batch_cnt	New	The maximum number of partitions that can be scheduled in each batch for batch compaction scheduling. This parameter is a tenant-level parameter. The default value is `50000`. In scenarios with millions of partitions, you can increase the value of this parameter to speed up compaction, which however increases CPU consumption and results in longer thread scheduling time.
server_cpu_quota_min	Modified	The default value is changed from `1` to `0`, and the value range is changed to [0, 16]. The value `0` indicates that the specifications of the `sys` tenant are adaptive.
server_cpu_quota_max	Modified	The default value is changed from `1` to `0`, and the value range is changed to [0, 16]. The value `0` indicates that the specifications of the `sys` tenant are adaptive.

Recommended versions of tools

The recommended platform tool versions for OceanBase Database V4.2.1 are described in the following table:

Tool	Version	Remarks
OceanBase Database Proxy (ODP)	V4.2.1.0	-
OCP	V4.2.0	We recommend that you use the latest BP version.
OceanBase Developer Center (ODC)	V4.1.3 BP3	ODC V4.2.2 will be released soon.
OceanBase CDC	V4.2.0	-
OceanBase Migration Service (OMS)	V4.2.0	-
OceanBase C++ Call Interface (OCCI)	V1.0.3	-
OceanBase Call Interface (OBCI)	V2.0.7	-
Embedded SQL in C for OceanBase (ECOB)	V1.1.8	-
OceanBase Command-Line Client (OBClient)	V2.2.3	-
OceanBase Connector/C	V2.2.3	-
OceanBase Connector/J	V2.4.5.1	V2.4.5 or later is required.
OceanBase Connector/ODBC	V2.0.8	-

Upgrade notes

An online upgrade of OceanBase Database Community Edition from V4.2.0 to V4.2.1 is supported.
An online upgrade of OceanBase Database Community Edition from V4.1.0 to V4.2.1 is supported.
We recommend that you upgrade OceanBase Database before you upgrade ODP.
During the upgrade, the system automatically disables major compactions and DDL operations. After the upgrade is complete, the system resumes normal operation.
An online upgrade of OceanBase Database Community Edition from V3.x to V4.2.1 is not supported.
You can upgrade OceanBase Database Community Edition from V3.x to V4.2.1 through logical data migration by using OMS.