Planet MySQL

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  1. Glimpse of MySQL 8.0.28 Release

     MySQL 8.0.28 version is GA!!! , ready to use in production.Below is high level overview , more can be viewed from the weblink.[1] Disabling Audit Logging for all connecting and connected sessionsSET GLOBAL audit_log_disable = true;Setting audit_log_disable to true disables the audit log plugin. The plugin is re-enabled when audit_log_disable is set back to false, which is the default setting.[2]- [Under Performance Schema] A new statement metric, CPU_TIME, is now available, enabling you to measure the CPU time spent on a query.This is helpful to troubleshoot performance of SQL statements specially hardware resource utilize by the SQL statement , below is the there table you can use to monitor the bottlenecks[3]- InnoDB now supports ALTER TABLE... RENAME COLUMN operations using ALGORITHM=INSTANTOperations that support ALGORITHM=INSTANT only modify metadata in the data dictionary. No exclusive metadata locks are taken on the table during preparation and execution phases of the operation, and table data is unaffected, making the operations instantaneous. If not specified explicitly, ALGORITHM=INSTANT is used by default by DDL operations that support it.[4]- Replication: When the PAD_CHAR_TO_FULL_LENGTH SQL mode was enabled on a replica server, trailing spaces could be added to a replication channel’s name in the replication metadata repository tables, resulting in errors in replication operations that identified the channel using that data. The issue has now been fixed in MySQL 8.0 by using VARCHAR for character columns, and in MySQL 5.7 by disabling the SQL mode when reading from those tables. Thanks to Brian Yue for the contribution. (Bug #33213841)[5.]Producing a per-table dump using mysqldump in MySQL 5.7 and 8.0 requires a longer execution time compared to MySQL 5.6. This is because the information_schema.files table, which is queried for information on log file groups by mysqldump, contains information about InnoDB data files as well as NDB data files from MySQL 5.7.In MySQL 8.0 , the issue has been fixed by rewriting the query to select only the appropriate data files. In MySQL 5.7, Information Schema tables do not have indexes, so a full table scan is still required. (Bug #29210990, Bug #93875)More info:-  https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-28.html
  2. MySQL 8.0.28 Release Note Commentary

     MySQL Server version  8.0.28 was launched a few days ago and without a lot a fanfare. Which is a shame and I wish we had more of a splash for every release.  The release notes are available here. I would like to highlight some of the changes.There are over a hundred bug fixes and big thanks to Hope Lee, Casa Zhang, Øystein Grøvlen, Song Zhibai, Facebook, Hobert Lu, Brian Yue, Zhai Weixiang, Murakami Kohei,  Venkatesh Prasad Venugopal, and the Tencent team.The HighlightsThis release does not have a lot of 'wow' new features but shows a lot of solid work in evolving the product. The new audit_log_disable system variable permits disabling audit logging for all connecting and connected sessions.The output from EXPLAIN FORMAT=TREE was ex-encoded ranges for multi-valued indexes Now, hex-encoding is used only for string types having a binary character set. Strings with non-binary character sets are now printed  as plain text, with escaping for any special characters. Now, hex-encoding is used only for string types having a binary character set. Strings with non-binary character sets are now printed in EXPLAIN FORMAT=TREE output as plain text, with escaping for any special characters. The shortcuts ASCII for CHARACTER SET latin1 and UNICODE for CHARACTER SET ucs2 are now deprecated, and you should expect their removal in a future version of MySQL. Using either of these now raises a warning; use CHARACTER SET instead.The character sets ucs2, macoman, macce, dec, and hp4  along with all of their collations, are now deprecated, and subject to removal in a subsequent release of MySQL. You should use utf8mb4 instead of any of the character sets just listed.The GnuPG build key used to sign MySQL downloadable packages has been updated. The previous GnuPG build key is set to expire on 2022-02-16. For information about verifying the integrity and authenticity of MySQL downloadable packages using GnuPG signature checking, or to obtain a copy of our public GnuPG build key, (Yup, it took a little while to get the new key out there when '28 was first published -- appologies!)A new Performance Schema statement metric, CPU_TIME, is now available, enabling you to measure the CPU time spent on a query.The number of distinct windows which can appear in a given SELECT is now limited to 127. The number of distinct windows is the sum of the named windows and the implicit windows specified as part of any window function's OVER clause. In order to use a large number of windows, it may be necessary to increase the value of the thread_stack server system variable. (Not sure just how you count the number of implicit windows!)So, please download this new version ASAP.All opinions expressed in this blog are those of Dave Stokes who is actually amazed to find anyone else agreeing with him
  3. Tips to Optimize MySQL Applications Query Performance

    Performance issues are often stubborn things to cure. Suddenly a query or operation seems slow, or slower-ish. Sadly, the database is often pointed at as the culprit by developers who are either positive their code cannot be at fault or those who see databases as a mysterious box that does odd things...
  4. MySQL Query Optimization: Top 3 Tips

    MySQL Query Optimization is usually simple engineering. But seeking information about how to tune queries is treated on many web reference sites like some Harry Potter-ish spell casting. There are simple tips you need to be aware of to get the best of your queries...
  5. MySQL Performance Tuning: Top 10 Easy Tips

    MySQL is a proven, reliable database that is quick to set up easy to maintain, and has outstanding performance. However, that performance can usually be improved with the judicious use of the following tips that are all easy to implement...

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