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Showing entries 1 to 10 of 18 8 Older Entries

Displaying posts with tag: MySQL 5.4 (reset)

Found a nasty COALESCE() related bug in 5.5.6-rc
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Seeing as it looks like 5.5 is shortly about to go GA I thought I’d give it a run and see how well it works. The only way really to test it is to give it a bit of load and look for things which break. That I did with the 5.5.6-rc community rpms, compared to the 5.1 advanced rpms I usually run.

My colleagues, Ben and Peter, found a horrible problem which means that I can’t use this even for any real usage on my real servers. See: bug#57095 for all the gory details. Thanks to them both for finding the problem and then digging down and figuring out the real cause. Sometimes …

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Video: Giuseppe Maxia Presents MySQL 5.4
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At the May 2009 Boston MySQL User Group, Giuseppe Maxia of Sun Microsystems gave a presentation about MySQL 5.4 with use cases and benchmarks to show how it outperforms all other current MySQL releases (including the Google patches and the OurDelta/Percona releases).

The slides can be downloaded from http://www.slideshare.net/datacharmer/mysql-54-theory-and-practice

The video can be watched below, or directly on YouTube at http://www.youtube.com/watch?v=giT4SYXuVqA&hl

What’s new in MySQL 5.4.1
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Absolutely nothing?

5.4.0 was released with a change in the MySQL Binary distributions, delivering only 1 64bit Linux platform and two Sun Solaris platforms. This was officially announced on April 21 2009 however the 5.4.0 Release Notes state 05 April 2009. So it’s not a big deal, but consistency would be nice.

I’ve seen in a few posts 5.4.1, so I …

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SHOW RELAYLOG EVENTS
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I reported a bug about SHOW BINLOG EVENTS not working with relay logs a couple of years ago - Bug #28777.

It’s now been fixed in MySQL 5.4, by adding a new SHOW statement - SHOW RELAYLOG EVENTS.

The replication team are really hammering through things at the moment - Kudos!

Follow-up Analysis of Split Rollback Segment Mutex
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I performed a new set of tests of the patch to split the
rollback segment mutex on Linux. All these tests gave
positive results with improvements in the order of 2%.

One could also derive from the results some conclusions.
The first conclusion is that this split mainly improves
things when the number of threads is high and thus
contention of mutexes is higher. At 256 threads a number
of results improved up to 15%.

The numbers on lower number of threads were more timid
although in many cases an improvement was still seen.

What was also noticeable was that the …












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Results of shootout on split page hash in InnoDB
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I have now tried out the buffer split page hash patches on
both a Linux/x86 box and a SPARC/Solaris server (tests done
by Dimitri).

The three variants in short description are:
1) The Google v3 derived patch. This introduces a new array
of mutexes that only protect the buffer page hash. Thus some
extra checking is needed to ensure the page hasn't been
removed from the hash before using it. This is a very simple
and attractive patch from that point of view. The patch uses
an array of 64 mutexes.

2) A variant I developed with some inspiration from the Percona …











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MySQL 5.4 Webinar
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The quality of MySQL 5.4.0 is very high for a beta product.
Four weeks after we released it as beta we have not had
any real serious bugs reported yet. There are some issues
due to deprecation of features, version numbers and a
bug in the SHOW INNODB STATUS printout and some concerns
with the new defaults when running on low-end machines.
It's also important as usual to read the documentation
before upgrading, it contains some instructions needed to
make an upgrade successful. The upgrade issue comes from
changing the defaults of the InnoDB log file sizes.

For those of you who want to know more …










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Patches ready for buf page hash split shootout
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Today I created a patch that builds on the Google v3
patch where I added some ideas of my own and some ideas
from the Percona patches. The patch is here.

Here is a reference to the patch derived from the Google
v3 patch.

Here is a reference to my original patch (this is likely to
contain a bug somewhere so usage for other than benchmarking
isn't recommended).

So it …










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Analysis of split flush list from buffer pool
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In the Google v3 patch the buffer pool mutex have been
split into an array of buffer page hash mutexes and a
buffer flush list mutex and the buffer pool mutex also
remains.

I derived the patch splitting out the buffer flush list
mutex from the Google v3 patch against the MySQL 5.4.0
tree. The patch is here.

I derived a lot of prototype patches based on MySQL 5.4.0
and Dimitri tried them out. This particular patch seems
to be the most successful in the pack of patches we
tested. It had a consistent positive …











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Shootout of split page hash from InnoDB buffer pool mutex
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One of the hot mutexes in InnoDB is the buffer pool mutex.
Among other things this mutex protects the page hash where
pages reside when they are in the cache.

There is already a number of variants of how to split out
this mutex. Here follows a short description of the various
approaches.

1) Google v3 approach
Ben Hardy at Google took the approach of using an array of
mutexes (64 mutexes) and this mutex only protects the
actual read, insert and delete from the page hash table.
This has the consequence of a very simple patch, it means
also that when the block …












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Showing entries 1 to 10 of 18 8 Older Entries

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