MariaDB 10.2首个GA 10.2.6发布，MySQL分支版本

MariaDB 10.2 首个 GA 10.2.6 发布了。新版采用 InnoDB 为默认存储引擎，更多更新如下：

新版本特性

InnoDB as default

• InnoDB is now the default storage engine. Until MariaDB 10.1, MariaDB used the XtraDB storage engine as default

Syntax / general features

• MyRocks alpha storage engine added (MDEV-9658)

• Window functions have been introduced.

• The SHOW CREATE USER statement was introduced

• New CREATE USER options for limiting resource usage and tls/ssl

• New ALTER USER statement

• Recursive Common Table Expressions (MDEV-9864)

• New WITH statement.WITHis a common table expression that allows you to  refer to a subquery expression many times in a query (MDEV-8308 & MDEV-9864) — Original code from Galina Shalygina

• Support for CHECK CONSTRAINT (MDEV-7563)

• Support for DEFAULT with expressions (MDEV-10134)

• BLOB and TEXT fields can now have aDEFAULTvalue

• Lots of restrictions lifted for Virtual computed columns

• Number of supported decimals in DECIMAL has increased from30to38(MDEV-10138)

• Added catchall for list partitions (MDEV-8348)

• Oracle-style EXECUTE IMMEDIATE statement (MDEV-10585)

• PREPARE Statement now understands most expressions (MDEV-10866)

• InnoDB tables now support spatial indexes

• ed25519 authentication plugin (MDEV-12160)

• Better InnoDB crash recovery progress reporting (MDEV-11027)

• Improvements to InnoDB startup/shutdown to make it more robust

• AWS Key Management plugin added for Windows, CentOS, RHEL, and Fedora packages

Triggers

• Multiple triggers for the same event (MDEV-6112)

• The FOLLOWS/PRECEDES clauses have been added to the CREATE TRIGGER statement

• Multiple triggers are now counted in the Executed_triggers status variable (MDEV-10915)

• SHOW TRIGGERS and SHOW CREATE TRIGGER now include the date and time the trigger was created

Replication / binary log

• DML_only flashback can rollback instances/databases/tables to an old snapshot (MDEV-10570)

• New variable read_binlog_speed_limit permits restricting the speed at which the slave reads the binlog from the master (MDEV-11064) — Original code from Tencent Game DBA Team, developed by chouryzhou.

• Delayed replication is supported (MDEV-7145)

• Compression of events in the binary log is supported (MDEV-11065) — Original code from Tencent Game DBA Team, developed by vinchen.

• Default binary log format changed to mixed (MDEV-7635)

• Default value of replicate_annotate_row_events changed toON(MDEV-7635)

• Default value of slave_net_timeout reduced to 60 seconds (MDEV-7635)

• Default server_id changed from0to1

GeoJSON / JSON

• JSON functions added (MDEV-9143)

• Implement ST_AsGeoJSON and ST_GeomFromGeoJSON functions so the spatial features can be imported/exported using GeoJSON format (MDEV-11042)

Information Schema

• An information schema plugin to report all user variables, which creates the Information Schema USER_VARIABLES Table (MDEV-7331)

EXPLAIN

• EXPLAIN FORMAT=JSON now showsouter_ref_conditionfield which contains the condition that the(?) SELECT checks on each re-execution (MDEV-9652)

• EXPLAN FORMAT=JSON now showssort_keyfield which shows the sort criteria used byfilesortoperation.  (commit 2078392)

• EXPLAIN used to show incorrect information about how the optimizer resolvedORDER BYclause orDistinct. This was a long-standing problem with roots back in MySQL. Now, after MDEV-8646 and related fixes,  the problem doesn't exist anymore.  (For test cases, see MDEV-7982, MDEV-8857, MDEV-7885, MDEV-326)

Optimizations

• Connection setup was made faster by moving creation of THD to new thread (MDEV-6150)

• Pushdown conditions into non-mergeable views/derived tables (MDEV-9197) — Original code from Galina Shalygina

• ANALYZE TABLE has been re-implemented so as not to lock the entire table when collecting engine independent statistics (MDEV-7901)

• Internal CRC32 routines use the optimized implementation on Power8 — MDEV-9872

• Table cache can automatically partition itself as needed to reduce the contention (MDEV-10296)

Compatibility

• NO PAD collations, which means that end space are significant in comparisons (MDEV-9711) — Original code from Daniil Medvedev

• MariaDB now works when started with a MySQL 5.7.6+ data directory (MDEV-11170)

CONNECT

• Zipped File Tables for the CONNECT storage engine (MDEV-11295)

• The CONNECT engine now supports the JDBC Table type (MDEV-9765)

System variables

For a list of all new variables, see System Variables Added in MariaDB 10.2 and Status Variables Added in MariaDB 10.2. These include:

• aria_recover has been renamed to aria_recover_options (MDEV-8542)

• Default values of the aria_recover and myisam_recover_options system variables changed toBACKUP,QUICK

• The server version can now be faked to work around dated applications that require a particular version string (MDEV-7780

• slave_parallel_workers is now an alias for slave_parallel_threads

• New status variables com_alter_user, com_multi and com_show_create_user

• New variable for setting a directory for storing temporary non-tablespace InnoDB files, innodb_tmpdir

• New variable read_binlog_speed_limit permits restricting the speed at which the slave reads the binlog from the master (MDEV-11064)

• innodb_log_files_in_group can now be set to1(MDEV-12061)

• The thread pool now gives higher priority to connections that have an active transaction. This can be controlled with the new thread_pool_prio_kickup_timer and thread_pool_priority system variables. (MDEV-10297)

• Default value of group_concat_max_len changed to 1M (MDEV-7635)

• Default value of innodb_compression_algorithm changed tozlib- this does not mean pages are now compressed by default, see compression (MDEV-11838)

• Default value of innodb_log_compressed_pages changed toON(MDEV-7635)

• Default value of innodb_use_atomic_writes and innodb_use_trim changed toON

• The unused innodb_api_* variables have been removed (MDEV-12050)

New status variables

• innodb_have_punch_hole

• innodb_pages0read

• innodb_scrub_log

• innodb_encryption_num_key_requests

Scripts

• Continuous binary log backup has been added to mysqlbinlog (MDEV-8713)

• mysql_zap and mysqlbug have been removed (MDEV-7376, MDEV-8654)

Other changes

• Added support for OpenSSL 1.1 and LibreSSL (MDEV-10332)

• Persistent AUTO_INCREMENT for InnoDB (MDEV-6076)

• Support COM_RESET_CONNECTION (MDEV-10340)

• "fast mutexes" have been removed. These aren't faster than normal mutexes, and have been disabled by default for years (MDEV-8111)

• Old GPL client library is gone; now MariaDB Server comes with the LGPL Connector/C client library (MDEV-9055)