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MySQL changed the timestamp format in the log files in MySQL 5.7. Since then, I have a few times seen questions about the new format, and how to change the time zone that is used. Latest in a comment to my blog about log_slow_extra in 8.0.14, where the question was what T and Z in the timestamp (for example 2019-01-31T07:24:06.100447Z) means. In this blog, I will discuss the timestamp format and show you how you can change the time zone used.

Examples of the timestamps from the MySQL error log when restarting MySQL (click to enlarge).
The MySQL 5.7 Change

In MySQL 5.7 it was decided to make two …

Last week I came across a bug in MySQL 8.0, which meant that the absence of mysql.user leads to auto-apply of –skip-grant-tables (#94394) would leave MySQL running in an undesirable state. My colleague Sveta Smirnova blogged about the issue and it also caught the interest of Valeriy Kravchuk in Fun with Bugs #80 – On MySQL Bug Reports I am Subscribed to, Part XVI. Thanks for the extra visibility!

Credit is now due to Oracle for the quick response, as it was fixed in less than one week (including a weekend):

Fixed in 8.0.16.

Previously, if the grant tables were corrupted, the MySQL server
wrote a message to …

MySQL User camp is one of the prestigious MySQL meetup happening in India for the past 6 years. Mydbops DBA’s PonSuresh and Vignesh has presented about the “JSON functions and their improvements in MySQL 8.0” at MySQL User Camp Bangalore on 13-02-2019.

JSON has been more improved a lot in MySQL 8.0 and improvements in LOB storage of MySQL boost it performance further. This presentation covers the JSON performance enhancements in MySQL 8.0 with its basic functions.

JSON improvements in MySQL 8.0 from Mydbops

Percona Server for MySQL 8.0 comes with enterprise grade total data encryption features. However, there is always the question of how much overhead – or performance penalty – comes with the data decryption. As we saw in my networking performance post, SSL under high concurrency might be problematic. Is this the case for data decryption?

To measure any overhead, I will start with a simplified read-only workload, where data gets decrypted during read IO.

During query execution, the data in memory is already decrypted so there is no additional processing time. The decryption happens only for blocks that require a read from storage.

For the benchmark I will use the following workload:

sysbench …

MySQL 8.0.15 performs worse in sysbench oltp_read_write than MySQL 5.7.25

Initially I was testing group replication performance and was puzzled why MySQL 8.0.15 performs consistently worse than MySQL 5.7.25.

It appears that a single server instance is affected by a performance degradation.

My testing setup

Hardware details:
Bare metal server provided by packet.net, instance size: c2.medium.x86
24 Physical Cores @ 2.2 GHz
(1 X AMD EPYC 7401P)
Memory: 64 GB of ECC RAM

Storage : INTEL® SSD DC S4500, 480GB

This is a server grade SATA SSD.

Benchmark

sysbench oltp_read_write --report-interval=1 --time=1800 --threads=24 --tables=10 --table-size=10000000 --mysql-user=root --mysql-socket=/tmp/mysql.sock run

In the following summary I used these combinations:

• innodb_flush_log_at_trx_commit=0 or 1
• Binlog: …

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The X DevAPI allows you to work with JSON documents and SQL tables at the same time. Furthermore, the CRUD style API is more intuitive than SQL statements for some programmers. Either way, the X DevAPI allows you to mix JSON documents, SQL tables, CRUD methods, and SQL statements to give you the best of all worlds. In MySQL Connector/Python, the X DevAPI is implemented in the mysqlx module.

This blog will look at how MySQL Connector/Python handles expressions, and how you in version 8.0.14 and later need to use the mysqlx.expr() method to explicitly define expressions.

Information

…

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When things go horrible wrong and a process crashes, one of the most powerful things to investigate the cause of the crash is a core dump. As the amount of memory allocated to processes such as MySQL has increased – in some cases approaching 1TiB of memory – enabling core dumps can cause problems of their own. MySQL Server 8.0.14 and later supports an option to reduce the size of the core dump which will be discussed in this blog.

Typically the largest single user of memory for MySQL is the InnoDB buffer pool. This is used to cache the data and indexes for tables using the InnoDB storage engine (the default). It is rarely important to know what is stored in the InnoDB buffer pool when investigating a crash, so a good way to …

Last week I presented the following session at the pre-FOSDEM MySQL Day:

MySQL Shell : the best DBA tool ? from Frederic Descamps

The audience seemed very interested on how the MySQL Shell can be extended.

During the presentation I showed how I extended the MySQL Shell with two new modules in Python:

• mydba
• innotop

Both projects are on github and are waiting for ideas, feature requests, pull requests, …

Here is …

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MySQL Server has a feature where you can insert data into a table from a file with the data delimited by commas, tabs, or another delimiter. This is particularly useful when you need to bulk import data, for example when restoring a backup or migrating data from one system to another including from another database product than MySQL. The mysqldump backup utility is an example of a program that supports exporting the data to delimited text files.

The statement to load the data is LOAD DATA INFILE. By default the file must be server-side and MySQL …

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The slow query log is the trusted old method of recording slow query, so the database administrator can determine which queries are in the most need for optimization. Since MySQL 5.6, it has to some extend been overshadowed by the Performance Schema which has lower overhead and thus allows collecting statistics about all queries. The slow query log has one major advantage though: the data is persisted. In MySQL 8.0.14 which was recently released, there is an improvement for the slow query log: additional statistics about the recorded queries.

The slow query log with log_slow_extra enabled.

Contribution

Thanks for Facebook for …