PlanetMysql.ru — информация о СУБД MySQL

Lot of talk lately about the effectiveness or lack thereof of the MySQL query cache.  I’m kind of surprised we are still having this discussion in late 2009, I really thought these issues have been long settled.

It’s well known that the query cache is terrible for environments with a constant stream of writes.  Each write invalidates the cached results for every query touching that table.  This means that your database needs to be constantly inserting and purging the query cache in an environment with mixed reads and writes (aka the most common type of “Web 2.0″ workload you’ll pardon the outdated cliché).

But now, Mark’s post goes one step further and reveals that even in a completely read-only environment, the query cache is still not effective.  This was news to me, as I haven’t even bothered testing this feature in a few years.  I’m sure if you really tried you could devise a scenario where it would outperform the InnoDB default, and it seems that consultants have encountered some installations where it has helped.  However I’m quite certain that in a well-designed modern workload, the query cache is not going to be a good approach.

The obvious alternative solution is to use an external caching system, preferably a L1/L2 cache using APC/memcached or similar.  Combine that with the most excellent MySQL/memcached UDF to intelligently prune your cache and you’ve got a system that easily can achieve performance at high concurrency.

I know what I’m saying here is not exactly breaking news (memcached was created 6 years ago), this really is the standard implementation now… my only point is that any discussion about the query cache that doesn’t suggest an external L1/L2 cache is missing the most important aspect.

Drizzle made the right call to remove the query cache feature entirely, with a plugin interface to optionally support that as needed.  That approach may be too drastic for MySQL itself, which still has some low-end use cases that may be able to get a performance benefit from it (and where the caches may be too much overhead).  In my opinion though, it should be disabled or set to DEMAND by default in a future version (and maybe ship the memcached UDF plugin too!).  Is it too late for 5.4 GA?

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The source version for MySQL Cluster 6.3.27 has now been made available at ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/mysql-5.1.37-ndb-6.3.27/

You can either wait for the binaries to be released or if you’re in a rush then you can find instructions on building the binaries for yourself in the earlier article: “MySQL Cluster 7.0.7 source released“.

A description of all of the changes (fixes) that have gone into MySQL Cluster 6.3.27 (compared to 6.3.26) can be found in the MySQL Cluster 6.3.27 Change Log.

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The source version for MySQL Cluster 7.0.8 has now been made available at ftp://ftp.mysql.com/pub/mysql/download/cluster_telco/mysql-5.1.37-ndb-7.0.8/

You can either wait for the binaries to be released or if you’re in a rush then you can find instructions on building the binaries for yourself in the earlier article: “MySQL Cluster 7.0.7 source released“.

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.0.8 (compared to 7.0.7) can be found in the MySQL Cluster 7.0.8 Change Log.

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Today we received a bug report saying that we shouldn't throw an exception but instead return what MySQLdb is returning. Bit research and MySQLdb is actually returning None for illegal dates: good!
There is now a fix (showing up soon) on Launchpad which will return dates as None where they are inserted as '0000-00-00'.
A few lines of Python:

..
data = [
   (datetime.now().date(),datetime.now()),
   ('0000-00-00','0000-00-00 00:00:00'),
   ('1000-00-00','9999-00-00 00:00:00'),
   ]

for d in data:
   stmt_insert = "INSERT INTO %s (c1,c2) VALUES (%%s,%%s)" % (tbl)
   try:
       cursor.execute(stmt_insert, d)
   except (mysql.connector.errors.InterfaceError, TypeError) as e:
       print "Failed inserting %s\nError: %s\n" % (d,e)

   if cursor.warnings:
       print cursor.warnings
..

The script outputs the following data, and notice also the warnings (SQL Mode set to NO_ZERO_IN_DATE,NO_ZERO_DATE):

[(u'Warning', 1265L, u"Data truncated for column 'c1' at row 1"),
 (u'Warning', 1264L, u"Out of range value for column 'c2' at row 1")]
[(u'Warning', 1265L, u"Data truncated for column 'c1' at row 1"),
 (u'Warning', 1264L, u"Out of range value for column 'c2' at row 1")]
(datetime.date(2009, 9, 30), datetime.datetime(2009, 9, 30, 15, 12, 23))
(None, None)
(None, None)

Another change we did today was returning a row as tuple, and rows as list of tuples.

Tip: use STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE SQL modes in MySQL 5.0 and later for new projects to make sure no illegal dates are inserted, or fix your application.
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The open-source database company's one-time chief executive is now entrepreneur in residence at a leading Silicon Valley venture capital firm.
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MySQL Cluster 7.0.8 was released as a source distribution 30th of Sept 2009. You should upgrade if you can build from source or use the Configurator.

See below how to upgrade when using the Configurator.

7.0.8 contains a number of fixes in almost every area and you are recommended to upgrade if you experience problems with earlier version(s). Especially if you have encountered the "error 306" problem.

The Configurator v2.9 has been updated to use this version.

If you are already using the Configurator and build from source you can upgrade from MySQL Cluster 7.0.7 to 7.0.8 (and you are recommended to upgrade because of the following changes/fixes) in four steps. Here is how:

1. run the upgrade-707-to-708-src.sh script (put it in install/ and chmod u+x ./upgrade-707-to-708-src.sh):

[cluster01]# pwd
/root/mysqlcluster-70-master/cluster/scripts/install
[cluster01]# chmod u+x ./upgrade-707-to-708-src.sh
[cluster01]# ./upgrade-707-to-708-src.sh
Upgrading scripts
done - now run ./download-and-compile.sh

2. run the script download-and-compile.sh

[cluster01]# ./download-and-compile.sh
After some time it will finish compiling:

mysql-7.0.8-linux-x86_64/sql-bench/test-alter-table
mysql-7.0.8-linux-x86_64.tar.gz created
Removing temporary directory
Downloaded binary distribution to ../../repo

(the 'downloaded binary' should really read 'Copied binary').

3. When you get prompted with the following question answer 'y' (yes):

Do you want to install the binaries on the hosts now
(else run 'install-cluster.sh' later)? (y/n):y

Important! Do not run the the bootstrap.sh script!!
4. change directory to the scripts/ to directory and run the ./rolling-restart.sh script

[cluster01]# pwd
/root/mysqlcluster-70-master/cluster/scripts/
[cluster01]# ./rolling-restart.sh

This in an online procedure so it requires no downtime of the Cluster.
If you are using binary distributions then you have to wait, because they are not ready yet.
Good luck!

Ps - Configurator 2.9 (released 2nd of September 2009) contains some minor fixes:

• Adding of [mysqld] slot for administration purposes
• ./start-backup now backup the configuration files (config.ini, my.cnf and some internal files) as well.

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With thousands of votes from the Zimbra community submitted to our product management database, and tens of thousands of hours logged by our engineering team, we are excited to officially announce Zimbra Collaboration Suite 6.0.

 

ZCS 6.0 is chock full of everything you asked for - because we made sure to check off the hit list of top requests. Some of the highlights include improved delegation and share management, increased productivity with three-pane email view, read receipts, remote wipe for mobile devices, and more. Our goal was also to make ZCS 6.0 the most flexible product yet, so we’ve also made it easier than ever to integrate 3^rd party software. You can learn more about the new features in 6.0 later today in a deep-dive blog post.

 

But that’s not the only recent milestone: Did you ever wonder what Zimbra and South Africa have in common? No it’s not our love for South African Hip Hop or Kwaito … it is that Zimbra just bested their population of 49.3 million because today, we have surpassed the 50,000,000th paid mailbox mark. Meaning if all Zimbra users made up their own country they would be the 25^th most populous in the world, edging up on Italy (Pasta anyone?). It’s amazing that we were able to gain ten million paid mailboxes just six months after reaching 40 million. Those 50 million accounts are spread across over 100,000 organizations that are now using Zimbra throughout the globe. That leap can only be attributed to our wonderful collection of partners and developers who continually remind us what people need so we can deliver the best collaboration product on the market.

 

We’ve been lucky to have the opportunity to work with a wide range of customers – from enterprises such as Computer Sciences Corporation, Mediacom, and WebMD to new government organizations including The Drug Enforcement Administration (DEA), Greece’s Ministry of Foreign Affairs, and Oman’s Ministry of Health; to educational institutions like Swarthmore College, Ecole Polytechnique de Montreal, and Savannah College of Art and Design.

 

 

Below are images a new mash-up built around ZCS 6 platform enhancements enabling Zimlets to be core application tabs.  “Zimbra Social” keeps you on top of all your Facebook, Twitter and Digg goodness.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

So, thanks again for all your support and feedback; hope you enjoy ZCS 6.0!
Network Edition server download | Open Source Edition server download

 

You can also find a bit more about what’s new in ZCS 6 on the Zimbra website.

PlanetMySQL Voting: Vote UP / Vote DOWN

With thousands of votes from the Zimbra community submitted to our product management database, and tens of thousands of hours logged by our engineering team, we are excited to officially announce Zimbra Collaboration Suite 6.0.

 

ZCS 6.0 is chock full of everything you asked for - because we made sure to check off the hit list of top requests. Some of the highlights include improved delegation and share management, increased productivity with three-pane email view, read receipts, remote wipe for mobile devices, and more. Our goal was also to make ZCS 6.0 the most flexible product yet, so we’ve also made it easier than ever to integrate 3^rd party software. You can learn more about the new features in 6.0 later today in a deep-dive blog post.

 

But that’s not the only recent milestone: Did you ever wonder what Zimbra and South Africa have in common? No it’s not our love for South African Hip Hop or Kwaito … it is that Zimbra just bested their population of 49.3 million because today, we have surpassed the 50,000,000th paid mailbox mark. Meaning if all Zimbra users made up their own country they would be the 25^th most populous in the world, edging up on Italy (Pasta anyone?). It’s amazing that we were able to gain ten million paid mailboxes just six months after reaching 40 million. Those 50 million accounts are spread across over 100,000 organizations that are now using Zimbra throughout the globe. That leap can only be attributed to our wonderful collection of partners and developers who continually remind us what people need so we can deliver the best collaboration product on the market.

 

We’ve been lucky to have the opportunity to work with a wide range of customers – from enterprises such as Computer Sciences Corporation, Mediacom, and WebMD to new government organizations including The Drug Enforcement Administration (DEA), Greece’s Ministry of Foreign Affairs, and Oman’s Ministry of Health; to educational institutions like Swarthmore College, Ecole Polytechnique de Montreal, and Savannah College of Art and Design.

 

 

Below are images a new mash-up built around ZCS 6 platform enhancements enabling Zimlets to be core application tabs.  “Zimbra Social” keeps you on top of all your Facebook, Twitter and Digg goodness.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

So, thanks again for all your support and feedback; hope you enjoy ZCS 6.0!
Network Edition server download | Open Source Edition server download

 

You can also find a bit more about what’s new in ZCS 6 on the Zimbra website.

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Has anyone read the report Microsoft, IBM and Oracle Lead the SMB and Mid-Market Database Segment - Yankee Group - 7/31/2006 - 5 Pages - ID: YANL1327246?

Paying 800USD just to know the percentages of each database is a bit expensive for my small startup budget, especially since it is not me who needs the information.

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The linux.conf.au organisers have given all miniconfs an additional few weeks to spruik for more proposal submissions, huzzah!

So if you didn’t submit a proposal because you weren’t sure whether you’d be able to attend LCA2010, you now have until October 23 to convince your boss to send you and get your proposal in.

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