MogDB 3.1.0

1. Version Description

MogDB 3.1.0 was released on Dec 30, 2022, further enhanced as preview version based on version 3.0 and incorporated with new features of openGauss 3.1.0.

2. New Features

2.1 Incorporated with New Features of openGauss 3.1.0

• The performance of basic operators is improved.

• Two-City Three-DC DR is supported.

• The CM supports external status query and push.

• The DCF supports policy-based majority.

• DBMind autonomous O&M platform

• Intelligent optimizer is supported.

• The fine-grained Any permission is enhanced.

• The compression capability of row-store tables is enhanced.

• Publication and subscription capabilities are enhanced.

• Fine-grained rolling upgrade is supported.

• The diagnosis capability of the statement_history view is enhanced.

Refer to the openGauss 3.1.0 feature description for details: New Features (opengauss.org)

2.2 Adaptive Row-level Compression Enhanced

This feature inherits the row-level compression feature of MogDB 3.0: compressing by row, eliminating decompression amplification; using background compression, reducing the impact on load performance; multi-page shared dictionary / self-developed optimized compression algorithm, improving the compression ratio. The compression optimization currently only supports astore storage, and the compression ratio reaches about 2 times for typical scenarios, and up to 25 times for specific data sets.

Related page: Enhancement of Astore Row-Level Compression

2.3 BTree Non-unique Index Compression

Supports compressing and storing BTree non-unique index data in deduplicate, thus saving the space occupied by index data.

The space saving ratio of index compression for different data types can be about 70%.

Related page: BTree Index Compression

2.4 Sorting Operator Optimization

Enhance the performance of data sorting in the following usage scenarios: optimize the performance of single column sorting; optimize the sorting of common data types (date, timestamp, uuid, text, varchar, char, etc.); support incremental sorting.

The performance improvement of each scenario is: about 20% for single column sorting; about 10% for optimizing sorting of common data types; more than 10 times for incremental sorting in memory-constrained scenarios.

Related page: Sorting Operator Optimization

2.5 Parallel Index Scanning

When querying data using indexes, multi-threaded parallel index scans are supported, thus significantly improving query efficiency.

Currently, indexscan, indexonlyscan and bitmapscan parallel index scan are supported.

Parallel index scan only supports BTree indexes, and does not support partitioned tables.

Related page: Parallel Index Scanning

2.6 CM Supporting Two-Node Deployment

The CM cluster management component supports a two-node deployment scheme based on ensuring high cluster availability and data consistency.

Related page: CM Supporting Two-Node Deployment

2.7 gstrace SQL Trace

Realize dynamic capture and observation capability of real SQL operation condition under non-stop database scenario to improve database observation and diagnostic tuning.

Related page: SQL Tracing

2.8 Enhanced Background Key Thread Trace Observation

Enhance the gstrace capability of walwriter, pagewriter and checkpointer threads to enable non-stop database observation and diagnostic tuning of the working state of background threads.

Related page: Trace Observation Enhancement

2.9 Extension Decoupling From Server Side

Decoupling of extensions, support for independent package release, independent installation and extension upgrade separately.

Note that currently the whale extensions are built-in extensions and have not been decoupled.

Related page: Extension Splitting

3.Fixed Defects

3.1 Incorporate Fixed Defects in openGauss 3.1.0

• I5LATD: When query_dop is set to 4, an error is reported when a query containing cube and Windows is executed.
• I5RWR4: After the 2.0.4-3.1.0 gray upgrade is successfully rolled back, the rollback fails and an error is reported.
• I5E52H: In a column-store table that contains long columns, the “could not open relation with OID” error may be reported after DML and vacuum deltamerge.
• I5FQHH: Read-only status is lost after the CM cluster is restarted.
• I5N6E6: After work_mem is set to 4MB and try_vector_engine_strategy is set to force, a core dump occurs when a complex subquery is executed.
• I5LI7Y: When query_dop is set to 1, an error is reported during FULL JOIN query. When query_dop is set to 4, no error is reported.
• I5MM6P: After parallel parsing is enabled, an LSN error is returned in the case of multiple transactions. As a result, data is parsed repeatedly after the application is restarted.
• I53M9A: TYPE IS TABLE OF prints garbled GBK characters in the GBK environment.
• I56S1E: When the column type in the database table is tinyint, the data type obtained by the cursor is str.
• I5FIZ1: After the try_vector_engine_strategy parameter is set to force, a table is created, and an incremental materialized view is created, the result of querying the materialized view is incorrect.
• I5E46Z: When -p is left blank or the port number is incorrect in the assessment statement, the error message is incorrect.
• I5EOSI: The migration tool fails to migrate data online, and the migration tool page keeps refreshing.
• I5EDAR: When a user-defined function is migrated, the function body contains return, and an error is reported during migration.
• I5E4CE: When max_sync_workers_per_subscription is set to 0, no message is displayed indicating that basic data cannot be synchronized.
• I5EDVY: After data is inserted into a table online, the data is not synchronized to openGauss. After another table is created, the data is migrated to openGauss.
• I56B7E: When LIKE.. EXCLUDING is used to create a table, there is no row-store compression parameter.

3.2 Fixed Defects in MogDB 3.1.0

• Fix the issue of sampling the same table in the same sql, specifying the same random number seedseed, returns different results
• Fix the issue of the delete event of xlogdump export identity full
• Fix the issue that ustore table using whale extension causes the database to be down and cannot be started.

4. Compatibility

This version supports the following operating system and CPU architecture combinations.

OS	CPU Architecture	Note
CentOS 7.x	X86_64 (Intel, AMD, Hygon, ZHAOXIN)
Redhat 7.x	X86_64 (Intel, AMD, Hygon, ZHAOXIN)
openEuler 20.03LTS	ARM (Kunpeng)、X86_64 (Intel, AMD, Hygon, ZHAOXIN)
Kylin V10	ARM (Kunpeng)、X86_64 (Intel, AMD, Hygon, ZHAOXIN)	OM is not compatible with openssh-8.2p1-9.p06 or above (including p06, p07, p08, p09) in the Kylin V10 sp2 upgrade patch for now.
UOS V20-D / V20-E	ARM (Kunpeng)、X86_64 (Intel, AMD, Hygon, ZHAOXIN)
UOS V20-A	X86_64 (Intel, AMD, Hygon, ZHAOXIN)