Category Archives: Generic
The Debian project has today announced their 9th release, code named “Stretch”. This is a big milestone for MariaDB, because the release team decided to ship and support only one MySQL variant in this release, and MariaDB was chosen over MySQL.
This is prominently mentioned in the press release about Debian 9 and more information can be found in the Debian release notes. We have also written an article in the Knowledge Base about MySQL to MariaDB migration in Debian. Everything has been designed to work so that the upgrade from MySQL 5.5 in Debian 8 to MariaDB 10.1 in Debian 9 should be automatic and smooth. …
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Usually when one says “SSL” or “TLS” it means not a specific protocol but a family of protocols. Wikipedia article has the details, but in short — SSL 2.0 and SSL 3.0 are deprecated and should not be used anymore (the well-known POODLE vulnerability exploits the flaw in SSL 3.0). TLS 1.0 is sixteen years old and while it’s still being used, new security standards (for example PCI DSS v3.1) require TLS 1.1 or, preferably, TLS 1.2.
MySQL used to support TLS 1.0 since 2001. Which means MariaDB supported it from the day one, and never supported weaker SSL 2.0 or SSL 3.0. …
InnoDB holepunch experiments
After excellent blogs by Mark Callaghan (see links below), I decided to use some of my time to experiment how different filesystems behave if the holepunch feature is used in MariaDB 10.1. First of all, MariaDB 10.1 does not use holepunch by default even if a table is page compressed (a term used in MariaDB). The holepunch feature in MariaDB is enabled with the innodb-use-trim=1 configuration variable and naturally requires support of the fallocate system call with the FALLOC_FL_PUNCH_HOLE and FALLOC_FL_KEEP_SIZE parameters. Support for these is checked during the cmake build phase.
I used CentOS Linux release 7.1.1503 (Core) using the 3.10.0-229.el7.x86_64 Linux kernel and few SSD drives in a RAID-0 setup (Intel X25-E Extreme SSDSA2SH032 G1GN 2.5-inch 32GB SATA II SLC Internal Solid State Drive (SSD)). …
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Introduction
A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table. The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. The purpose of the foreign key is to identify a particular row of the referenced table. Therefore, it is required that the foreign key is equal to the candidate key in some row of the primary table, or else have no value (the NULL value). This is called a referential integrity constraint between the two tables. …
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Introduction
Fortran (FORmula TRANslating System) is a general-purpose, imperative programming language that is especially suited to numeric computation and scientific computing. History of FORTRAN can be tracked late 1953 when John W. Backus submitted a proposal to his superiors at IBM. The First FORTRAN compiler appeared in April 1957.
Some notable historical steps where:
- FORTRAN II in 1958
- FORTRAN III in 1958,
- FORTRAN IV in 1962.
- FORTRAN 66 or X3.9-1966 become the first industry-standard
- FORTRAN 77 or X3.9-1978. This is the version of the Fortran I learned 1996.
…
Last week, a SSL connection security vulnerability was reported for MySQL and MariaDB. The vulnerability states that since MariaDB and MySQL do not enforce SSL when SSL support is enabled, it’s possible to launch Man In The Middle attacks (MITM). MITM attacks can capture the secure connection and turn it into an insecure one, revealing data going back and forth to the server.
Issue resolution in MariaDB is visible through the corresponding ticket in MariaDB’s tracking system (JIRA): https://mariadb.atlassian.net/browse/MDEV-7937
The vulnerability affects the client library of the database server in both MariaDB and MySQL. But, the vulnerability does not affect all the libraries, drivers or connectors for establishing SSL connections with the server. …
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About two and a half years ago I wrote about how the MariaDB project moved bug reporting from Launchpad to JIRA. Every now and then I get contacted about how it was done and whether I would be willing to share the tools used for doing it and of course I’ve done that. Especially in one occasion the scripts were even further developed by one company that was in the process of doing exactly the same, i.e. moving bugs from Launchpad to JIRA. Thanks for the enhancements Philip Colmer from Linaro!
In Launchpad there isn’t a readymade tool for exporting bugs and I didn’t find any 3rd party tools for doing it. …
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Introduction
Causal consistency [1] is one of the consistency criteria that can be used on distributed databases as consistency criteria.
Distributed database provides causal consistency if read and write operations that are causally related are seen by every node of the distributed system in the same order. Concurrent writes may be seen in different order in diffrent nodes. Causal consistency is waker than sequential consistency [2] but stronger than eventual consistency [3]. See earlier blog for more detailed description on eventual consistency https://blog.mariadb.org/eventually-consistent-databases-state-of-the-art/.
When a transaction performs a read operation followed later by a write operation, even on different object, the first read is said to be causally ordered before the write. …