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Displaying posts with tag: community (reset)
The MySQL 5.7 Optimizer Challenge

In the MySQL team, we have been working really hard on refactoring the optimizer and improving the cost model. The hacks of storage engines lying to the optimizer are being rolled back, and your chances of getting an optimal query plan should now be much higher than in prior releases of MySQL.

The optimizer team has also allowed cost constants to be configurable on both a server and a storage engine basis, and we are confident that the default InnoDB engine will always work “as good as MyISAM” (which has a natural advantage, in that the optimizer was originally largely built around it.)

Today, I want to issue a challenge:

Find an example where the …

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MySQL 5.7.8 – Now featuring super_read_only and disabled_storage_engines

I wanted to highlight two new features that are making their way into MySQL 5.7 via the not-yet-released 5.7.8-rc2:

  • A new system variable super_read_only allows a more strict definition of ‘read-only’ which also applies to super users.
  • A new disabled_storage_engines setting offers a way to prevent an enumerated list of storage engines from being used. For example, a DBA may wish to enforce an InnoDB-only policy to simplify common operations such as backups, but it’s possible MyISAM may sneak back in via new code-deployments. This setting allows more active …
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Proposal to deprecate INSERT and REPLACE alternative syntax

In the MySQL team we are currently considering a proposal to deprecate a number of alternative syntax uses with the INSERT and REPLACE commands. To provide examples:

CREATE TABLE `city` (
  `ID` int(11) NOT NULL AUTO_INCREMENT,
  `Name` char(35) NOT NULL DEFAULT '',
  `CountryCode` char(3) NOT NULL DEFAULT '',
  `District` char(20) NOT NULL DEFAULT '',
  `Population` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`),
  KEY `CountryCode` (`CountryCode`),
  CONSTRAINT `city_ibfk_1` FOREIGN KEY (`CountryCode`) REFERENCES `Country` (`Code`)
) ENGINE=InnoDB AUTO_INCREMENT=4080 DEFAULT CHARSET=latin1;

INSERT INTO city SET
 Name='NewCity', CountryCode='CAN',District='MyDistrict',Population=1234;

INSERT INTO city (Name,CountryCode,District,Population) VALUE
 ('NewCity2', 'CAN', 'MyDistrict', 1234);

INSERT city (Name,CountryCode,District,Population) VALUES
 ('NewCity3', 'CAN', 'MyDistrict', 1234);
 
REPLACE INTO city (Name,CountryCode,District,Population) VALUE …
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Proposal to deprecate MySQL INTEGER display width and ZEROFILL

In the MySQL team we are currently discussing if we should deprecate the integer display width in numeric types. For example:

CREATE TABLE my_table (
 id INT(11) NOT NULL PRIMARY KEY auto_increment
);

The (11) does not affect the storage size of the data type, which for an INT will always be 4 bytes. It affects the display width.
Our rationale for proposing this should be deprecated is that it is a common source of confusion amongst users.

We are …

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Plan to deprecate PROCEDURE ANALYSE

In the MySQL team, we have been refactoring the SQL parser to be more maintainable. Gleb Shchepa lists the goals of this project in more details on the MySQL Server Team blog.

As part of this, we have identified the feature PROCEDURE ANALYSE as something that we would like to deprecate. For added context, here is a demonstration:

mysql> SELECT * FROM City procedure analyse()\G
*************************** 1. row ***************************
             Field_name: world.city.ID
              Min_value: 1
              Max_value: 4079
             Min_length: 1
             Max_length: 4
       Empties_or_zeros: 0
                  Nulls: 0
Avg_value_or_avg_length: 2040.0000 …
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An update on GROUP BY implicit sort

In the MySQL team, we have been planning for some time to remove the implicit sorting that is provided by GROUP BY. In doing so, we will make a number of existing queries faster (by no longer requiring a sort) as well as unlock opportunities to implement further optimizations.

This is one of the more complicated behaviours to remove, because it is not possible to tell if an application relies upon implicit ordering. Since a GROUP BY query without an ORDER BY clause is a valid query, it is also not reasonable to issue deprecation warnings.

However, one piece of the puzzle that was missing when I last wrote about this problem, is that MySQL 5.7 will …

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SHOW ENGINE INNODB MUTEX is back!

We received feedback from a number of users in the MySQL community that the command SHOW ENGINE INNODB MUTEX remains useful in a number of scenarios. We listened, and the command is scheduled to make a return in MySQL 5.7.8.

To lessen overhead, the command will now feature a mechanism to enable and disable metrics collection. This is documented in the manual here:

SET GLOBAL innodb_monitor_enable='latch';
SET GLOBAL innodb_monitor_disable='latch';

Thank you for helping make a better MySQL!

A quick update on our native Data Dictionary

In July 2014, I wrote that we were working on a new native InnoDB data dictionary to replace MySQL's legacy frm files.

This is quite possibly the largest internals change to MySQL in modern history, and will unlock a number of previous limitations, as well as simplify a number of failure states for both replication and crash recovery.

With MySQL 5.7 approaching release candidate (and large changes always coming with risk attached) we decided that the timing to try to merge in a new data dictionary was just too tight. The data dictionary development is still alive and well, but it will not ship as part of MySQL 5.7.

So please stay tuned for updates... and thank you for using MySQL!

News from the third MariaDB Foundation Board Meeting this year

The MariaDB Foundation Board has been meeting monthly since February and on Monday this week had the third meeting of the year. Here is an update on a couple of things from the meeting.

We’re happy to announce that Booking.com has renewed their support to the foundation. As a major corporate sponsor Booking.com has been offered a seat on the Foundation board. Booking.com nominated Eric Herman.  Eric has a history with MySQL dating from 2004 where he joined MySQL working on the server and tools.  In 2010, Eric joined Booking.com where he works on database scaling challenges and BigData. As a community member, he has contributed to the perl MySQL client driver, the perl interpreter, and other Free Software.  To represent community and industry interests in line with the Foundation mission, Eric Herman has joined the Board.

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"awesome-mysql" curated list created, open for pull requests

Following up on popular "awesome-*" lists (e.g. awesome-python, awesome-golang etc.), I've created the awesome-mysql curated list.

This is a list of technologies (and resources) in and around MySQL, and means to serve as a place to find reliable software and info. I recently happened to notice there are some tools I'm familiar with that are unknown to others; tools unknown to me that are in good use.

The list is naturally and intentionally incomplete. I wish this to be a community based creation; so I put some categories and some tools. I left many out, deliberatey. Please assist by filling in the missing projects, tools, libraries! Additions gladly accepted via …

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