MariaDB 10.4 首个 GA 版本 10.4.6 发布，带来多项更新

MariaDB 10.4.6 发布了，MariaDB 10.4.6 是一个 GA 稳定版。MariaDB主要由开源社区在维护，采用 GPL 授权许可。

发布日期:2019.06.18

MariaDB 10.4 是 MariaDB 10.3 的演进版，带来了几个全新功能，并且具有 MySQL 的后端和重新实现的功能。

Authentication

• See  Authentication from MariaDB 10.4  for an overview of the changes.
• The  unix_socket authentication plugin  is now default on Unix-like systems, which is a major change to authentication in MariaDB ( MDEV-12484 )
• User password expiry  ( MDEV-7597 )
• Account Locking  ( MDEV-13095 )
• The obsolete  mysql.host table  is no longer created ( MDEV-15851 )
• Much faster privilege checks for MariaDB setups with many user accounts or many database grants ( MDEV-15649 )
• mysql.user  table is retired. User accounts and global privileges are now stored in the  mysql.global_priv  table ( MDEV-17658 )
• SET PASSWORD  support for  ed25519  and other  authentication plugins  ( MDEV-12321 )

InnoDB

• Added instant  DROP COLUMN  and changing of the order of columns ( MDEV-15562 )
• Reduced redo log volume for undo tablespace initialization ( MDEV-17138 )
• Removed crash-upgrade support for pre-10.2.19 TRUNCATE TABLE ( MDEV-13564 )
• Added key rotation for  innodb_encrypt_log  ( MDEV-12041 )
  • Implement  innodb_checksum_algorithm=full_crc32  ( MDEV-12026 )
  • More Instant VARCHAR extension ( MDEV-15563 )
  • Instant collation or charset changes for non-indexed columns ( MDEV-15564 )
  • Use in-memory PK filters built from range index scans ( MDEV-16188 )

Optimizer

• Implementation of the  optimizer trace , one can enable the optimizer trace by enabling the system variable  optimizer_trace  ( MDEV-6111 )
• Engine Independent Table Statistics  is now enabled by default; new default values are  use_stat_tables=PREFERABLY_FOR_QUERIES  and  optimizer_use_condition_selectivity=4  ( MDEV-15253 )
  • Two new values for the variable  use_stat_tables :  COMPLEMENTARY_FOR_QUERIES  and  PREFERABLY_FOR_QUERIES  ( MDEV-17255 )
  • Histograms  are now collected by default ( MDEV-18608 ).
  • analyze_sample_percentage  variable added. The default value is 100 ( ANALYZE  will use the whole table), but one can also set analyze to only use a sample of table data to collect the statistics.
• Push conditions into materialized IN subqueries  ( MDEV-12387 )
• The  optimizer switch  flag  optimize_join_buffer_size  now defaults to  on  ( MDEV-17903 )
• New  optimizer switch  flags  rowid_filter  and  condition_pushdown_from_having

Syntax

• System-versioning  extended with support for  application-time periods .
• Support of brackets (parentheses) for specifying precedence in  UNION / EXCEPT / INTERSECT  operations ( MDEV-11953 )
• New  FLUSH SSL  command to reload SSL certificates without server restart ( MDEV-16266 )
• New  CAST  target —  CAST(x AS INTERVAL DAY_SECOND(N))  ( MDEV-17776 )
• IF NOT EXISTS  clause added to  INSTALL PLUGIN  and  IF EXISTS  clause added to  UNINSTALL PLUGIN  and  UNINSTALL SONAME  ( MDEV-16294 )

Variables

For a list of all new variables, see System Variables Added in MariaDB 10.4 and  Status Variables Added in MariaDB 10.4 .

• Added to the  tcp_nodelay  system variable ( MDEV-16277 )
• Removed the  Innodb_pages0_read  status variable ( MDEV-15705 ).
• New  sql-mode  setting,  TIME_ROUND_FRACTIONAL  ( MDEV-16991 )
• New variable  gtid_cleanup_batch_size  for determining how many old rows must accumulate in the  mysql.gtid_slave_pos  table before a background job will be run to delete them.
• The default for  eq_range_index_dive_limit  is now  200  (previously  0 ) ( MDEV-18551 )
• core_file  on Windows now defaults to  ON  ( MDEV-18439 )

Galera

Galera 4 version 26.4.0 has been added to  MariaDB 10.4

Upgrading to Galera 4 version 26.4.0

Rolling upgrades from earlier 10.3 (or older) MariaDB releases are not supported in this release. For upgrading a 10.3-based cluster, any applications accessing the cluster should be stopped and the cluster shut down. Then for each cluster node the following procedure should be carried out:

• Install  MariaDB 10.4.2  and Galera 4 version 26.4.0
• Start MariaDB server, but make sure it is not trying to connect to the cluster by configuring  wsrep_provider=none
• While MariaDB server is running, run  mysql_upgrade  for the server
• Stop MariaDB server

After that, you can bootstrap the cluster. If there was ongoing application load on the cluster during the initial cluster shutdown phase, you should make sure to bootstrap the cluster with the node which was shutdown last.

We are working on rolling upgrade support for the final GA version of MariaDB 10.4 . With a rolling upgrade, a live cluster can be upgraded node by node, and the cluster is able to process application load when having a hybrid setup of 10.3 and 10.4 nodes.

New Features in Galera 26.4.0

The ‘mysql’ schema contains new Galera replication related tables:

wsrep_cluster
wsrep_cluster_members
wsrep_streaming_log

End users may read but not modify these tables.

The new streaming replication feature allows replicating transactions of unlimited size. With streaming replication, a cluster is replicating a transaction in small fragments during transaction execution. This transaction fragmenting is controlled by two new configuration variables:

• wsrep_trx_fragment_unit (bytes, rows, statements)  defines the metrics for how to measure transaction size limit for fragmenting. Possible values are:

  bytes
  rows
  statements
  

• wsrep_trx_fragment_size  defines the limit for fragmenting. When a transaction’s size, in terms of the configured fragment unit, has grown over this limit, a new fragment will be replicated.

Transactions replicated through galera replication will now process the commit phase using MariaDB's group commit logic. This will affect transaction throughput, especially when binary logging is enabled in the cluster.

Limitations in Galera 26.4.0

• Upgrading from 10.3 version 25.3.25 to 10.4 version 26.4.0 must happen on a stopped cluster. Only after all nodes have been upgraded to  MariaDB 10.4  and Galera 26.4.0 can the cluster be started up
• Splitting transactions of  LOAD DATA  execution will conflict with streaming replication, and should not be used if streaming replication is configured

General

• Crash safe  Aria -based  system tables  ( MDEV-16421 )
• Added Linux abstract socket support ( MDEV-15655 )
• Enabled C++11 ( MDEV-16410 )
• Performance improvements in  Unicode  collations ( MDEV-17534 ,  MDEV-17511 ,  MDEV-17502 ,  MDEV-17474 )
• User data type plugins ( MDEV-4912 , in progress)
• Improvements with SQL standard INTERVAL support to help functions  TIMESTAMP()  and  ADDTIME()  return more predictable results.
  • Historically, MariaDB uses the TIME data type for both "time of the day" values and "duration" values. In the first meaning the natural value range is from '00:00:00' to '23:59:59.999999', in the second meaning the range is from '-838:59:59.999999' to '+838:59:59.999999'.
  • To remove this ambiguity and for the SQL standard conformance we plan to introduce a dedicated data type INTERVAL that will be able to store values in the range at least from '-87649415:59:59.999999' to '+87649415:59:59.999999', which will be enough to represent the time difference between TIMESTAMP'0001-01-01 00:00:00' and TIMESTAMP'9999-12-31 23:59:59.999999'.
  • As a first step we support this range of values for intermediate calculations when TIME-alike string and numeric values are used in INTERVAL (i.e. duration) context, e.g. as the second argument of SQL functions TIMESTAMP(ts,interval) and ADDTIME(ts,interval), so the following can now be calculated:

SELECT ADDTIME(TIMESTAMP'0001-01-01 00:00:00', '87649415:59:59.999999');
-> '9999-12-31 23:59:59.999999'  

SELECT TIMESTAMP(DATE'0001-01-01', '87649415:59:59.999999')
-> '9999-12-31 23:59:59.999999'  

SELECT ADDTIME(TIME'-838:59:59.999999', '1677:59:59.999998');
-> '838:59:59.999999'

• Support for window  UDF functions  via the new method  x_remove  ( MDEV-15073 )
• Json service for plugins ( MDEV-5313 )
• Change in behavior for  FLUSH TABLES  ( MDEV-5336 ).
• The  JSON_VALID  function is automatically used as a  CHECK constraint  for the  JSON data type alias  in order to ensure that a valid json document is inserted ( MDEV-13916 )
• MariaDB Named Commands ( MDEV-17591 )

有关 MariaDB 10.4. 6 所做更改的完整列表，请参阅 更新日志 。