Pythian Group

Persistence Smoothie: Blending NoSQL and SQL – see user feedback and comments at http://joind.in/talk/view/1332.

Michael Bleigh from Intridea, high-end Ruby and Ruby on Rails consultants, build apps from start to finish, making it scalable. He’s written a lot of stuff, available at http://github.com/intridea. @mbleigh on twitter

NoSQL is a new way to think about persistence. Most NoSQL systems are not ACID compliant (Atomicity, Consistency, Isolation, Durability).

Generally, most NoSQL systems have:
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Most of this stuff is not PHP specific, and Python or Ruby or Java or .NET developers can use the tools in this talk.

The session on joind.in, with user comments/feedback, is at http://joind.in/talk/view/1320.

Slides are at http://talks.php.net/show/confoo10

“My name is Rasmus, I’ve been around for a long time. I’ve been doing this web stuff since 1992/1993.”

“Generally performance is not a PHP problem.” Webservers not config’d, no expire headers on images, no favicon.

Tools: Firefox/Firebug extension called YSlow (developed by yahoo) gives you a grade on your site.
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Baron makes an excellent point in Why you should ignore MySQL’s key cache hit ratio — ratio is not the same as rate. Furthermore, rate is [often] the important thing to look at.

This is something that, at Pythian, we internalized a long time ago when thinking about MySQL tuning. In fact, mysqltuner 2.0 takes this into account, and the default configuration includes looking at both ratios and rates.

If I told you that your database had a ratio of temporary tables written to disk of 20%, you might think “aha, my database is slow because of a lot of file I/O caused by writing temporary tables to disk!”. However, that 20% ratio may actually mean a rate of 2 per hour — which is most likely not causing excessive I/O.

To get a sense of this concept, and also how mysqltuner works, I will show the lines from the mysqltuner default configuration that deal with temporary tables written to disk. Read the rest of this entry . . .

There are those that are very adamant about letting people know that using INFORMATION_SCHEMA can crash your database. For example, in making changes to many tables at once Baron writes:

“querying the INFORMATION_SCHEMA database on MySQL can completely lock a busy server for a long time. It can even crash it. It is very dangerous.”

Though Baron is telling the truth here, he left out one extremely important piece of information: you can actually figure out how dangerous your INFORMATION_SCHEMA query will be, ahead of time, using EXPLAIN.

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This is the third post in Oracle GoldenGate Extract Internals series (links to part I and part II).

In this post, we’re going to take a closer look at various queries that the Extract process uses against the database. As before, we will start by examining the strace output:

nanosleep({1, 0}, NULL)                 = 0
...
read(20, "\1\"\0\0\255\1\0\0\217\0\0\0H\200\366\256\5\24\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1024000) = 1024000
...
write(16, "\0$\0\0\6\0\0\0\0\0\3N'\7\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7\0011"..., 36) = 36
read(17, "\0\351\0\0\6\0\0\0\0\0\6\1\"\375\2\0\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0"..., 8208) = 233
write(16, "\0 \0\0\6\0\0\0\0\0\3N(\10\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7\0011", 32) = 32
read(17, "\0\343\0\0\6\0\0\0\0\0\6\1\"\7\1\0\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0"..., 8208) = 227
write(16, "\0K\0\0\6\0\0\0\0\0\3N)\t\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7,/"..., 75) = 75
read(17, "\0\341\0\0\6\0\0\0\0\0\6\1\"\375\1\0\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0"..., 8208) = 225
write(16, "\0Q\0\0\6\0\0\0\0\0\3N*\n\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7,/"..., 81) = 81
read(17, "\0\254\0\0\6\0\0\0\0\0\4\1\0\0\0)\0\1\0\0\0\0{\5\0\0\0\0\n\0\0\0"..., 8208) = 172
lseek(20, 227328, SEEK_SET)             = 227328
nanosleep({1, 0}, NULL)                 = 0

File descriptors 16 and 17 are the pipes for one of the bequeath connections we have with the database. There are four queries being submitted each cycle (following the same order as those being sent to a database): Read the rest of this entry . . .

Today we continue looking at various aspects of how the Oracle GoldenGate extract process works.

One of the follow up questions to part I was about the way the Extract process reads from ASM storage. I’ve provided the answer, however, today we’re going get a detailed look at how the Extract process interacts with an ASM instance and what kind of implications may result.

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A couple of weeks ago Christo Kutrovsky mentioned to me about Oracle Streams presentation he saw on this year’s UKOUG. The presentation was from CERN’s Eva Dafonte Pérez and, among over things, Eva mentions about substantial performance enhancements observed in 11GR2.

It is somewhat timely that we’ve been doing some Oracle Golden Gate testing which in turn made me curious to take a closer look at Oracle Streams in 11GR2 and see where all the performance is coming from.

I’ve setup a simple replication for table t1 from schema src to schema dst, changed Apply Server parallelism to 1 and did a simple test with inserting 100 rows while performing a sql trace:
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OpenSQLCamp was a huge success! I took videos of most of the sessions (we only had 3 video cameras, and 4 rooms, and 2 sessions were not recorded). Unfortunately, I was busy doing administrative stuff for opensqlcamp for the opening keynote and first 15 minutes of the session organizing, and when I got to the planning board, it was already full….so I was not able to give a session.

• Comparing Non-Relational Databases: MongoDB, Tokyo Tyrant, CouchDB by Igal Koshevoy of Pragmaticraft
• Drizzle Client Rewrite – Clark Boylan leads the requirements and design discussion for rewriting the Drizzle Client
• Drizzle Plugin Hacking
• Drizzle is Not MySQL with Changes – Brian Aker gives a talk on Drizzle, and how Drizzle is not MySQL.
• Fractal Trees – by Bradley Kuszmaul of Tokutek
• Geographic Operators in SQL (PostGIS) by Webb Sprague
• Goal-Driven Performance – Peter Zaitsev speaks about how to achieve goal-driven performance.
• Graph Engine for MySQL – by Antony Curtis
• Intro to Cassandra
• An Intro to CouchDB: What caught Ubuntu’s eye by Mike Miller (Cloudant)
• Maria – MySQL founder Monty Widenius talks about Maria, and the past, present and future of MySQL.

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Welcome to week 2 of Blogrotate. It was a short week due to Thanksgiving (Canada) and Columbus Day (US), but the world of IT is always buzzing. So as they say at the race track, pitter-patter, let’s get at ‘er.
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This presentation was done by Sheeri Cabral of The Pythian Group and went into how to use SHOW ENGINE INNODB STATUS to get more information about your Innodb tables, foreign keys and transactions. This is a great presentation to learn how InnoDB works.

It also went through how to use SHOW ENGINE INNODB STATUS to tune several InnoDB variables:

innodb_adaptive_hash_index
innodb_commit_concurrency
innodb_concurrency_tickets
innodb_file_io_threads
innodb_log_buffer_size
innodb_max_purge_lag
innodb_sync_spin_loops
innodb_thread_concurrency
innodb_thread_sleep_delay

The slides can be downloaded from:

http://technocation.org/files/doc/ShowEngineInnoDBStatus.pdf

(Note that the slides open up to the middle section, which has slides plus notes, but if you just want the slides without notes, that starts on page 1 of the PDF.)

The video can be watched below, or directly on YouTube at http://www.youtube.com/watch?v=ocdjspoLM58