Tag: MariaDB

Feed: Planet MySQL; Author: Federico Razzoli; Federico Razzoli  | December 14, 2018 |  Posted In: MariaDB, MySQL PREVIOUS POSTAs mentioned in a previous post, I gave a talk at Percona Live Europe 2018 about system-versioned tables. This is a new MariaDB 10.3 feature, which consists of preserving old versions of a table rows. Each version has two timestamps that indicate the start (INSERT,UPDATE) of the validity of that version, and its end (DELETE, UPDATE). As a result, the user is able to query these tables as they appear at a point in the past, or how data evolved in a certain time ... Read More

Feed: Planet MySQL; Author: FromDual; As we already stated in earlier articles in this blog [ and ] it is a good idea to use NULL values properly in MariaDB and MySQL.One of my Mantras in MariaDB performance tuning is: Smaller tables lead to faster queries! One consequence out of this is to store NULL values instead of some dummy values into the columns if the value is not known (NULL: undefined/unknown). To show how this helps related to space used by a table we created a little example: CREATE TABLE big_null1 ( id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY ... Read More

Feed: What's New. In addition, you will now get an Amazon RDS event notification when a new minor version upgrade is available for your database instance or database cluster. This is useful when you are managing a large number of database instances and would like to be notified when engine version upgrades are available. You can consume Amazon RDS event notifications through the Amazon Simple Notification Service (Amazon SNS) or Amazon CloudWatch Events. These enhancements are available for the MySQL, MariaDB, Oracle, PostgreSQL and SQL Server database instances in all AWS Regions ... Read More

Feed: Microsoft Azure Blog. Author: Rob Caron. Microsoft Connect(); 2018 On Tuesday, December 4th, Microsoft Connect(); 2018 provided a full day of developer-focused content—including updates on Azure and Visual Studio, keynotes, demos, and real-time coding with experts. Scott Guthrie’s keynote provided all the Azure and Visual Studio news on how you can stay productive and focus on what matters to you. Guthrie’s keynote was followed by a demo-packed session hosted by Scott Hanselman and friends that provided a full tour on how you can build your apps on Azure using best-in-class developer tools. The day continued with coding sessions hosted ... Read More

Feed: MariaDB Knowledge Base Article Feed. Author: . When the user creates a temporary table using the CREATE TEMPORARY TABLE statement and the engine is set as InnoDB, MariaDB creates a temporary tablespace file. When the table is not compressed, MariaDB writes to a shared temporary tablespace as defined by the innodb_temp_data_file_path system variable. When compressed, the temporary table is written to a dedicated temporary tablespace for that table. MariaDB deletes temporary tablespaces when the server shuts down gracefully and is recreated when it starts again. It cannot be placed on a raw device. Internal temporary tablespaces, (that is, temporary ... Read More

Feed: MariaDB Knowledge Base Article Feed. Author: . When InnoDB needs to store general information relating to the system as a whole, rather than a specific table, the specific file it writes to is the system tablespace. By default, this is the ibdata1 file located in the data directory, (as defined by either the datadir or innodb_data_home_dir system variables). InnoDB uses the system tablespace to store the data dictionary, change buffer, and undo logs. You can define the system tablespace filename or filenames, size and other options using the innodb_data_file_path system variable. It defaults to ibdata1 at 12M set to ... Read More

Feed: MariaDB Knowledge Base Article Feed. Author: . When you create a table using the InnoDB storage engine, data written to that table is stored on the file system in a data file called a tablespace. Individual tablespaces can contain data from one or more InnoDB tables as well as the associated indexes. MariaDB uses one tablespace file per InnoDB table. You can optionally revert to the legacy behavior of storing all InnoDB table data in the system tablespace, by disabling the innodb_file_per_table system variable. Tablespace Locations Tables that use the InnoDB storage engine write to tablespaces stored in the ... Read More

Feed: Planet MySQL; Author: Valeriy Kravchuk; Probably all of us, MySQL users, DBAs and developers had seen error 1213 more than once, in one context or the other: mysql> select * from t1;ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction The first thing that comes to mind in this case is: "OK, we have InnoDB deadlock, let's check the details", followed by the SHOW ENGINE INNODB STATUS check, like this: mysql> show engine innodb statusG*************************** 1. row ***************************  Type: InnoDB  Name:Status:=====================================2018-12-08 17:41:11 0x7f2f8b8db700 INNODB MONITOR OUTPUT=====================================Per second averages calculated from the last 12 seconds-----------------BACKGROUND THREAD-----------------srv_master_thread ... Read More

Feed: Planet MySQL; Author: Severalnines; Queries have to be cached in every heavily loaded database, there is simply no way for a database to handle all traffic with reasonable performance. There are various mechanisms in which a query cache can be implemented. Starting from the MySQL query cache, which used to work just fine for mostly read-only, low concurrency workloads and which has no place in high concurrent workloads (to the extent that Oracle removed it in MySQL 8.0), to external key-value stores like Redis, memcached or CouchBase. The main problem with using an external dedicated data store (as we ... Read More

Feed: Planet MySQL; Author: Severalnines; Delayed replication allows a replication slave to deliberately lag behind the master by at least a specified amount of time. Before executing an event, the slave will first wait, if necessary, until the given time has passed since the event was created on the master. The result is that the slave will reflect the state of the master some time back in the past. This feature is supported since MySQL 5.6 and MariaDB 10.2.3. It can come in handy in case of accidental data deletion, and should be part of your disaster recovery plan. The ... Read More