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Displaying posts with tag: Databases (reset)
Q: Does MySQL support ACID? A: Yes

I was recently asked this question by an experienced academic at the NY Oracle Users Group event I presented at.

Does MySQL support ACID? (ACID is a set of properties essential for a relational database to perform transactions, i.e. a discrete unit of work.)

Yes, MySQL fully supports ACID, that is Atomicity, Consistency, Isolation and Duration. (*)

This is contrary to the first Google response found searching this question which for reference states “The standard table handler for MySQL is not ACID compliant because it doesn’t support consistency, isolation, or durability”.

The question is however not a simple Yes/No because it depends on timing …

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Do you control your database outages?

Working with a client last week I noted in my analysis, “The mysql server was restarted on Thursday and so the [updated] my.cnf settings seems current”. This occurred between starting my analysis on Wednesday and delivering my findings on Friday.

# more /var/lib/mysql/ip-104-238-102-213.secureserver.net.err
160609 17:04:43 [Note] /usr/sbin/mysqld: Normal shutdown

The client however stated they did not restart MySQL and would not do that at 5pm which is still a high usage time of the production system. This is unfortunately not an uncommon finding, that a production system had an outage and that the client did not know about it and did not instigate this.

There are several common causes and the “DevOps” mindset for current production systems has made this worse.

  • You have managed hosting and they perform software updates with/without your knowledge. I have for example worked with several Rackspace …
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Utilizing OpenStack Trove DBaaS for deployment management

Trove is used for self service provisioning and lifecycle management for relational and non-relational databases in an OpenStack cloud. Trove provides a RESTful API interface that is same regardless of the type of database. CLI tools and a web UI via Horizon are also provided wrapping Trove API requests.

In simple terms. You are a …

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The differences between IDEMPOTENT and AUTO-REPAIR mode

I posted recently Lossless RBR for MySQL 8.0 about a concern I have about moving to minimal RBR in MySQL 8.0.  This seems to be the direction that Oracle is considering, but I am not sure it is a good idea as a default setting. I talked about a hypothetical new replication mode lossless RBR and also about … Continue reading The differences between IDEMPOTENT and AUTO-REPAIR mode

Lossless RBR for MySQL 8.0?

Lossless RBR TL/DR: There’s been talk of moving the next release of MySQL to minimal RBR: I’d like to suggest an alternative: lossless RBR For MySQL 5.8 there was talk / suggestions about moving to minimal RBR as the default configuration (http://mysqlserverteam.com/planning-the-defaults-for-mysql-5-8/).  I’m not comfortable with this because it means that by default you do not have … Continue reading Lossless RBR for MySQL 8.0?

MySQL 5.7 Introduces a JSON Data Type

There's a new JSON data type available in MySQL 5.7 that I've been playing with. I wanted to share some examples of when it's useful to have JSON data in your MySQL database and how to work with the new data types (not least so I can refer back to them later!)

MySQL isn't the first database to offer JSON storage; the document databases (such as MongoDB, CouchDB) work on a JSON or JSON-ish basis by design, and other platforms including PostgreSQL, Oracle and SQL Server also have varying degress of JSON support. With such wide adoption as MySQL has, the JSON features are now reaching a new tribe of developers.

Why JSON Is Awesome

Traditional database structures have us design table-shaped ways of storing all our data. As long as all your records (or "rows") are the same shape and have the same sorts of data in approximately the same quantities, this works brilliantly well. There are some common problems that aren't a good …

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MySQL 5.7 Introduces a JSON Data Type

There's a new JSON data type available in MySQL 5.7 that I've been playing with. I wanted to share some examples of when it's useful to have JSON data in your MySQL database and how to work with the new data types (not least so I can refer back to them later!)

MySQL isn't the first database to offer JSON storage; the document databases (such as MongoDB, CouchDB) work on a JSON or JSON-ish basis by design, and other platforms including PostgreSQL, Oracle and SQL Server also have varying degress of JSON support. With such wide adoption as MySQL has, the JSON features are now reaching a new tribe of developers.

Why JSON Is Awesome

Traditional database structures have us design table-shaped ways of storing all our data. As long as all your records (or "rows") are the same shape and have the same sorts of data in approximately the same quantities, this works brilliantly well. There are some common problems that aren't a good …

[Read more]
MMUG15: MySQL 5.7 & JSON

English: The Madrid MySQL Users Group is pleased to announce its next meeting on February 10th 2016 at 7pm at the offices of Tuenti in Gran Via, Madrid.  Morgan Tocker of Oracle will be visiting to give a talk on MySQL 5.7 and JSON as part of a European tour.  This will give you an an … Continue reading MMUG15: MySQL 5.7 & JSON

MySQL RDS Point-in-time restore

RDS for MySQL on AWS allows you to restore to any point in time for your backup retention period, minus the last 5 minutes or so. Restoration creates a new instance, it does not overwrite whatever instance you’re restoring. AWS’s use of the word restore is a bit confusing because restore often means “take your production database server and overwrite it with data from a backup”. As far as I can tell, Amazon never means this. When you restore, AWS creates another database server and writes all the data to the new instance, both when you’re using restoring to a point-in-time or from a DB snapshot. If you needed to switch servers, you’d have to point your database to the new instance.

Reference

Is MySQL X faster than MySQL Y? – Ask queryprofiler

When trying out new software there are many other questions you may ask and one of those is going to be the one above. The answer requires you to have built your software to capture and record low level database metrics and often the focus of application developers is slightly different: they focus on how … Continue reading Is MySQL X faster than MySQL Y? – Ask queryprofiler

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