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Displaying posts with tag: facebook (reset)

InnoDB locking makes me sad
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Vadim and others have pointed at the index->lock problems before, but I think they didn’t good job enough at pointing out how bad it can get (the actual problematic was hidden somewhere as some odd edge case). What ‘index lock’ means is generally the fact that InnoDB has table-level locking which will kill performance on big tables miserably.

InnoDB is a huge pie of layers, that have various locking behaviors, and are layered on top of each other, and are structured nicely as subdirectories in your innodb_plugin directory. Low level storage interfaces are done via os/ routines, then on top of that there’s some file space manager, fsp/, which allocates space for btr/ to live in, where individual page/ entities live, with multiple row/ pieces.

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OurSQL Episode 50: MySQL at Facebook, Current and Future
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This week we post th' audio from th' closin' keynote o' Percona Live by Harrison Fisk o' Facebook, "MySQL at Facebook, Current and Future", I'll warrant ye. There is no ear candy this week.

Graph API & IFrame Base Facebook Application Development PHP SDK 3.0
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Facebook recently updated their PHP-SDK to version 3.0. This is a major change. So I decided to update some of my facebook related tutorials with updated code.

At first I want to tell you that, this post is the updated version of my popular post Graph API & IFrame Base Facebook Application Development . So if you never saw that tutorial I request you to visit that and learn the basic things specially facebook application setup. Also on that post I mentioned some important things regarding

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MySQL metrics for read workloads
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There are multiple metrics that are really useful for read workload analysis, that should all be tracked and looked at in performance-critical environments.

The most commonly used is of course Questions (or ‘Queries’, ‘COM_Select’) – this is probably primary finger-pointing metric that can be used in communication with different departments (“why did your qps go up by 30%?”) – it doesn’t always reveal actual cost, it can be increase of actual request rates, it can be new feature, it can be fat fingers error somewhere in the code or improperly handled cache failure.

Another important to note is Connections – MySQL’s costly bottleneck. Though most of users won’t be approaching ~10k/s area – at that point connection pooling starts actually making sense – it is

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On database write workload profiling
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I always have difficulties with complex analysis schemes, so fall back to something that is somewhat easier. Or much easier. Here I will explain the super-powerful method of database write workload analysis.

Doing any analysis on master servers is already too complicated, as instead of analyzing write costs one can be too obsessed with locking and there’s sometimes uncontrollable amount of workload hitting the server beside writes. Fortunately, slaves are much better targets, not only because writes there are single-threaded, thus exposing every costly I/O as time component, but also one can drain traffic from slaves, or send more in order to cause more natural workload.

Also, there can be multiple states of slave load:

  • Healthy, always at 0-1s lag, write statements are always immediate
  • Spiky, usually at 0s lag, but has jumps due to sometimes occuring slow
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451 CAOS Links 2011.03.08
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Digia gets Qt. VMware makes waves. Rackspace launches OpenStack support. And more.

Follow 451 CAOS Links live @caostheory on Twitter and Identi.ca, and daily at Paper.li/caostheory
“Tracking the open source news wires, so you don’t have to.”

# Digia signed an agreement with Nokia to acquire the Qt commercial licensing and services business.

# VMware’s Springsource division acquired Wavemaker.

# Rackspace formally launched services and support for OpenStack via Rackspace Cloud Builders.

# Red Hat defended its move to pre-apply patches to Red Hat


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A case for FORCE INDEX
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I remember various discussions in different mediums where people were building cases against use of FORCE INDEX in SQL queries. I’ll hereby suggest it using way more often, but at first I’ll start with small explanation.

For ages, the concept of index statistics affecting query plans has been clogging minds of DBAs, supported by long explanations of MyISAM and InnoDB manuals. Actually, statistics are used just for determining which index to use for a joined table, as predicate is not known at the time of ‘optimization’.

What happens if you do a simple query like:

SELECT * FROM table WHERE a=5 AND b=6

? If there’s an index that

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Percona Live Keynote Speaker: Mark Callaghan
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Mark Callaghan has graciously accepted to be the closing keynote speaker for Percona Live: San Francisco!

Mark is best known for his work behind MySQL @ Facebook, where he and his team maintain one of the largest MySQL installations around.  They also contribute back to the community with a publicly available branch of enhancements, improved diagnostic tools, and bug reports which help make MySQL better.

Mark’s keynote will be on “High-value Transaction Processing”.  I assure you, this is a presentation not to be missed.

Tech Messages | 2011-01-08
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A special extended edition of Tech Messages for 2011-01-07 through 2011-01-08:

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Logs memory pressure
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Warning, this may be kernel version specific, albeit this kernel is used by many database systems

Lately I’ve been working on getting more memory used by InnoDB buffer pool – besides obvious things like InnoDB memory tax there were seemingly external factors that were pushing out MySQL into swap (even with swappiness=0). We were working a lot on getting low hanging fruits like scripts that use too much memory, but they seem to be all somewhat gone, but MySQL has way too much memory pressure from outside.

I grabbed my uncache utility to assist with the investigation and started uncaching various bits on two systems, one that had larger buffer pool (60G), which was already being sent to swap, and a conservatively allocated (55G) machine, both 72G boxes. Initial

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10 Newer Entries Showing entries 31 to 40 of 100 10 Older Entries

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