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Previous 30 Newer Entries Showing entries 31 to 60 of 139 Next 30 Older Entries

Displaying posts with tag: Technical Blog (reset)

A review of Tungsten Replicator: Part 1 – Installation
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I’ve been following the development of Tungsten Replicator for quiet some time now, and recently was fortunate enough to find the time to take a look at the product in more detail. If you haven’t heard of Tungsten Replicator yet, it’s an open source database replication engine that can be used to complement or completely [...]
Curious case with MySQL replication
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MySQL Replication is a powerful tool and it’s hard to find a production system not using it. On the other hand debugging replication issues can be very hard and time consuming. Especially if your replication setup is not straightforward and you are using filtering of some kind.

Recently we got an alert from our monitoring system that replication stopped on production slave with the following error:

Can't find record in 'some_table', Error_code: 1032;
handler error HA_ERR_KEY_NOT_FOUND;
the event's master log binlog.000011, end_log_pos 735766642

This means that a ROW-based replication event was going to be applied on slave, but could not find the row it was supposed to be applied to. This is something I like about ROW format — it allows you to catch such data synchronization issues right away. In this particular case MIXED format was used, but if



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Alter waiting on Select statement to complete
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A few days ago, we faced an interesting problem on one of our customer’s slave mysqld servers.  An Alter for adding a new column was run on master server took 542 seconds where as it took few hours on the slave server to complete due to a SELECT blocking the Alter was not allowed to complete.

Here is the the select on the master server and it’s execution time from the binary logs.

# at 825737566
#110720 19:55:21 server id 31415  end_log_pos 825737730         Query   thread_id=83250629      exec_time=542   error_code=0
use collect/*!*/;
SET TIMESTAMP=1311216921/*!*/;
/*!\C latin1 *//*!*/;
SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8/*!*/;
ALTER TABLE `track` ADD `source_track_id` int(10) UNSIGNED NULL DEFAULT NULL  AFTER `vendor_track_id`
/*!*/;

Alter statement completed well on the



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Viewing RMAN jobs status and output
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Yesterday I was discussing with a fellow DBA about ways to check the status of existing and/or past RMAN jobs. Good backup scripts usually write their output to some sort of log file so, checking the output is usually a straight-forward task. However, backup jobs can be scheduled in many different ways (crontab, Grid Control, Scheduled Tasks, etc) and finding the log file may be tricky if you don’t know the environment well.
Furthermore, log files may also have already been overwritten by the next backup or simply just deleted. An alternative way of accessing that information, thus, may come handy.

Fortunately, RMAN keeps the backup metadata around for some time and it can be accessed through the database’s V$ views. Obviously, if you need this information because your database just crashed and needs to be restored, the method described here is useless.


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Oracle Exadata “technology that most changed his life” – says Oracle ACE & Pythian DBA Fahd Mirza.
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Pythian’s Oracle ACE, Fahd Mirza appears in this month’s Community: Peer-to-Peer review “In With the New“, as published in the September/October 2011 issue of Oracle Magazine.

Fahd states that “Oracle Exadata Database Machine” has most changed his life – changing the game, and setting very high standards of performance, support, scalability, reliability and unification.

Shout out to Fahd from your peers at Pythian!

I guess there might be just a little truth to Pythian’s growing reputation as an “Oracle ACE Factory” ;), as recently mentioned by Justin Kestelyn in the May 11, 2011 OPN PartnerCast:

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Watch for Pythian speakers at upcoming Oracle Technology Days, NoCOUG, OOUG, SQLSaturday & Pythian Australia.
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It’s a busy summer at Pythian, with our continuing wave of speaking sessions at upcoming community and regional industry events.

Coming to a city near you, watch for Pythian presenting hot Oracle and Microsoft SQL Server database topics:

IN CANADA:

Oracle Technology Days – Montreal
August 9, 2011 – 8:30am – 1pm, Hilton Montreal Bonaventure

Oracle Technology Days – Toronto
August 25, 2011




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Why you should submit a paper for an Oracle User Group event.
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In this post:

  • Introduction
  • Reasons to submit a paper for an Oracle User Group event
  • What should you talk about?

Introduction

Just a few days ago I received a reminder email from Burke Scheld for the “AUSOUG National Conference Series – Perth 2011 – Call for Papers”. I had an event-related conversation with several Oracle guys in my professional networks and the answers I received triggered this blog post. Some of the very good Oracle professionals I personally respect said “…I am not sure what I would get out of it …” or “…I haven’t done anything exciting for the last FEW MONTHS …”.
The answers I received shocked me a bit. Typically I am in the opposite situation where I have so many good things happening I would love to share with the world that I

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How to Run a Streaming Backup with innobackupex
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On many of our clients, we have a need to run XtraBackup as a regular OS user. Aside from running into the issue where tar4ibd was not provided with Percona’s xtrabackup-1.6.2.tar.gz package, our main issues have been with permissions when attempting a streaming backup.

I have found the following:

  • The user needs permissions for a temp directory to stream to/from. The my.cnf of the target database cannot be used because the user does not have permission to write to /tmp/mysql-stdout, so we set a tmpdir in a separate defaults-file.
  • A backup target directory must be used that the user has read/write permissions to. It seems to me a target directory should not be
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    Silent MyISAM Table Definition Changes and mysqldump
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    The other day while trying to move a schema from one MySQL server to another, I encountered a very odd issue. The schema to be moved contained both MyISAM and InnoDB tables, so the only option I had was to dump the schema using mysqldump on the source server and import it on the destination server. The dump on the source server went fine with absolutely no issues but it failed to import into the second server, and the error message was:

    Can't create/write to file ‘/disk1/activity.MYI’ (Errcode: 2)


    This was an extremely odd message as the data directory on the destination server was properly setup in terms of ownership and permission. The source and destination MySQL servers have been running without issues for months. Prior to the error, four tables in the dump file were imported into the destination server without any issues whatsoever.

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    Log Buffer #222, A Carnival of the Vanities for DBAs
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    As the birds have started their yearly migration back to their homes from the warmer areas to the relative less cooler areas in summer, bloggers are also touching base with the technologies which they cherish most and coming back with some master strokes. This new cool edition of Log Buffer, the coolest blog carnival covering hottest topics encompass that home coming. Now Chill with Log Buffer #222!!!

    Oracle:

    Charles Hooper blogs about an Overly Complicated Use Case Example regarding Row Values to Comma

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    Handling Human Errors
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    Interesting question on human mistakes was posted on the DBA Managers Forum discussions today.

    As human beings, we are sometimes make mistakes. How do you make sure that your employees won’t make mistakes and cause downtime/data loss/etc on your critical production systems?

    I don’t think we can avoid this technically, probably working procedures is the solution.
    I’d like to hear your thoughts.

    I typed my thoughts and as I was finishing, I thought that it makes sense to post it on the blog too so here we go…

    The keys to prevent mistakes are low stress levels, clear communications and established processes. Not a complete list but I think these are the top things to reduce the number of mistakes we make managing data infrastructure or for


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    Log Buffer #215, A Carnival of the Vanities for DBAs
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    Spring is making its way into everything, and the databases are blooming as the DBAs who manage them are savoring the fragrance of the changing weather and fresh new ideas in the world of blogging. In order to appreciate the springing blogging innovations, this week’s Log Buffer, Log Buffer #215 picks some of the flowers just for you.

    Oracle:

    Hemant, the Oracle ACE from Singapore writes superbly about OuterJoin with Filter Predicate as usual with a reproducible case.

    When

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    Log Buffer #213, A Carnival of the Vanities for DBAs
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    Warm welcome to the Log Buffer, a weekly amalgamation of database news across different technologies. Let’s get warmed up with sizzling Log Buffer #213.

    Oracle:
    ======

    One of the leading performance gurus, Kellyn Pederson is letting us know how she is finding the initial months at Pythian and she rightly praises her fabulous team mates Mark Brinsmead, Paul Logan, and Andy Klock.

    The famous Oracle Database Junkie – Arup Nanda, blogs more about Interested Transaction Lists.

    Universal Connection Pool, Oracle’s next


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    Beware Starting Slaves in the Position in the master.info file
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    I’ve seen many a good DBA make the master of starting slaves from the position in the master.info file, most recently this week, that I want to bring it to everyone’s attention. Of course I mean the underlying issue and not the names of the DBA because that would be cruel.

    In the typical scenario where this is an issue, the sequence of events is roughly the same with some small variation. A cold backup or a snapshot is restored onto a new server to build out a new slave. The binary log position from the master.info file, which is part of the backup, is used to start replication. Eventually after a short while, someone notices data discrepancies on the new slave compared to the master or replication stops due to an error.

    The problem can be best looked by looking the slave status output in MySQL like below:

    mysql> show slave
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    Log Buffer #210, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer, the weekly news update of happenings in the database world.

    Its the holiday season and many DBAs would rather cuddle at home with their family rather than do exciting work and blog about it. Can you imagine? Many thanks to Fahd Mizra who helped me by collecting DB2 news. Grab your snuggie and cuddle up with Log Buffer #210.

    MySQL:

    Giuseppe Maxia, the Data Charmer looked for a way to add comments into the binary log and created an interesting discussion on the topic.

    You’d think that having some

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    Log Buffer #209, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer, the weekly news update of happenings in the database world.

    A big shout out to Pythian team members Andrey, Gwen, Fahd, and Don for their submissions. We have lots of news and recommended reading this week so let’s get going with Log Buffer #209.

    Andrey Goryunov’s top picks:

    Dion Cho, the Oracle Performance Storyteller, provides an explanation of parallel DML execution plan.



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    Log Buffer #208, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer, the weekly round up of news and happenings in the database world.

    We’re planning our publishing calendar for 2011. Happy to announce that we’ll have a few guest hosts in the New Year. Don’t forget if you’d like to host or edit a future edition of Log Buffer on your own blog, send a note to the Log Buffer coordinator.

    We’ve had several contributions of favorite reads from the team this week. Enjoy this issue, Log Buffer #208.

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    Pythian at UKOUG Technology and E-Business Suite Conference 2010
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    Hello Birmingham!

    It’s past Sunday midnight and I’m stuck in my room in the last couple hours finishing my slides for my masterclass tomorrow. Turns out that I’m presenting the very first session of the conference at 9am. I wish there is a keynote instead so that I could grab one more hour of sleep (it’s going to be deep into the night back home in Canada). Strange that the keynote was moved to Wednesday — I hope UKOUG has really good reason for that!

    My two hours masterclass will start at the same time as Tom Kyte’s a-la keynote session — what a competition. On the other hand, there is no other sessions in server technology so I expect that folks without interest of database development will automatically end up in my session. I’m in Hall 5 – quite large room. Is it the second

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    Log Buffer #206, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer, the weekly news blog about blogs in the datasphere… As we kick off Log Buffer #206, our own Gwen Shapira shares a few of her weekly favorites:

    Oracle:

    Arup Nanda posted an excellent script on how to summarize backup information from the rman catalog. He also

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    Log Buffer #204, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer, the weekly roundup of happenings in the database world.

    Lots to cover this week, so let’s get on with Log Buffer #204. Enjoy!

    Oracle:

    Pythian’s Gwen Shapira dabbles with MySQL and explores MySQL troubleshooting for the Oracle DBA.

    Venkat Janakiraman explores how connectivity works for BI EE 11g

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    Log Buffer #203, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer. The weekly roundup of posts, and news of what’s happening in the database world.

    At Pythian, we’re pretty much recovered from a hectic Oracle OpenWorld 2010, and I’m no longer an OOW virgin. What an experience! I had the pleasure of meeting many of you Log Buffer readers and contributors at the Annual Blogger’s Meetup at Jillian’s. Great to put faces to names. And I now officially feel like “Vanessa from Log Buffer”, as many of your t-shirts will show.

    Many thanks to Marc Fielding for providing the hot items for this week’s post,

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    Log Buffer #202, A Carnival of The Vanities for DBAs
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    Welcome to Log Buffer, the weekly roundup of database industry news. We’re only a week or so away from Oracle OpenWorld. Everyone is buzzing with activity, promoting their speaking sessions and making last minute plans. For all of you bloggers who will be attending, don’t miss the annual Bloggers Meetup, announced recently by Alex Gorbachev. “Count yourself in” if you’ll be joining the gang so that accurate attendee numbers can be provided to Jillian’s to ensure everyone is well fed and watered ;)

    In recent days, if anything has created massive tremors  [Read more...]
    Bloggers Meetup @ Oracle OpenWorld 2010
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    It’s that time of the year again — Oracle OpenWorld time — and it’s my pleasure to announce our regular Oracle bloggers meetup again this year. We all know that Oracle community has grown this year so we expect to see folks from all the different technologies including MySQL, Java, Sun hardware folks in addition to the core Oracle database and apps crowd.

    So… all of you Oracle bloggers attending Oracle Open World 2010
    … you are invited to attend this Oracle Bloggers Meetup during OOW 2010 — a chance to meet your online buddies face-to-face in relaxed and informal atmosphere.

    When: Wed, 22-Sep-2010,


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    Log Buffer #199, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer. The weekly review of DBA industry news. Enjoy Log Buffer #199.

    Remember if you find a link or interesting blog post that you think Log Buffer should mention, send a note to the editor at Log Buffer and be sure to include the link, and a short note outlining why you think that particular post would be of value to other DBAs, or what you learned from reading it.

    And, for inquiries about hosting or editing a future edition of Log Buffer on your own blog, send your query to the Log

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    YAPCEU 2010 – Day Two…
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    After enjoying the excellent hospitality of our host here in Pisa (6 courses) we were ready for our second day at YAPCEU 2010 here in sunny Pisa.

    Larry’s new catch phrase “My Language is a four letter word” was the ‘Buzz word’ for today. We settled down to some very interesting talks, the highlight for me being Tim Bunce’s talk on using Devel::NYTProf to Optimize your code. Tim first gave us a quick and dirty overview of optimization which covered the basics of where to start and what to look for he followed up with real examples of Optimizer output and than wrapped up with a few before and after results on an optimization effort.

    The rest of the day was dedicated in my opinion, to the future of DBs in with Nelson Ferraz giving an excellent presentation of his concepts for using Perl as to glue for a Data Warehouse application. Next on my agenda,

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    Log Buffer #198, A Carnival of the Vanities for DBAs
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    Welcome to Log Buffer, a weekly review of the database industry. This week’s issue Log Buffer #198 is generously published by Sam DeFilippis, who manages Oracle Notes blogs, with latest postings on Oracle GoldenGate.

    As always, if you’d like to host your own issue of Log Buffer, simply reach out to the Log Buffer coordinator.
    Please enjoy Sam’s issue

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    Log Buffer #197, A Carnival of the Vanities for DBAs
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    Log Buffer #197 marks the middle of summer, and the fact that we’re a mere two weeks away from our 200th edition.

    To begin this week’s reading, I’d like to highlight two Oracle blogs maintained by Sam J. DeFilippis: Oracle Notes, where he’s recently posted about troubleshooting GoldenGate and positioning a read of Extract/Replicat Trail file or Oracle redo

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    A Pythian Fork
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    Today marks my last day at Pythian. I have been at Pythian for almost three years. In those three years, Pythian’s already thriving MySQL practice has grown even more. I have worked with big and small clients alike, across many industries, managed a team of up to 4 DBAs, and learned a lot not just about MySQL, but what my goals are in general.

    Though I am leaving, everything I said in the blog post I made when I announced I was coming to Pythian still holds true. Pythian is a challenging environment and one I would recommend to anyone who finds their current DBA environment boring that they should come to Pythian and experience what it is like to work here. I had lunch with Paul Vallee yesterday and we even discussed possible future collaborations (hence the title, a joke that I am

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    Data Warehousing Best Practices: Comparing Oracle to MySQL pt 2
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    At Kscope this year, I attended a half day in-depth session entitled Data Warehousing Performance Best Practices, given by Maria Colgan of Oracle. My impression, which was confirmed by folks in the Oracle world, is that she knows her way around the Oracle optimizer.

    See part 1 for the introduction and talking about power and hardware. This part will go over the 2nd “P”, partitioning. Learning about Oracle’s partitioning has gotten me more interested in how MySQL’s partitioning works, and

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    Data Warehousing Best Practices: Comparing Oracle to MySQL pt 1
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    At Kscope this year, I attended a half day in-depth session entitled Data Warehousing Performance Best Practices, given by Maria Colgan of Oracle. My impression, which was confirmed by folks in the Oracle world, is that she knows her way around the Oracle optimizer.

    These are my notes from the session, which include comparisons of how Oracle works (which Maria gave) and how MySQL works (which I researched to figure out the difference, which is why this blog post took a month after the conference to write). Note that I am not an expert on data warehousing in either Oracle or MySQL, so these are more concepts to think about than

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    Previous 30 Newer Entries Showing entries 31 to 60 of 139 Next 30 Older Entries

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