The Problem

I've had MySQL on my Windows 7 laptop for a bit (as part of wampserver), mostly for local offline WordPress development.

However, even though MySQL is relatively stable, I've been observing a vast quantity of intermittent MySQL errors, as reported by WordPress in the PHP error log (C:\wamp\logs\php_error.log). Here are some examples:

[05-Jan-2010 09:47:51] WordPress database error Error on delete of
'C:\Windows\TEMP\#sql17e0_1a2_6.MYD' (Errcode: 13) for query SELECT t.*, tt.*
FROM wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON tt.term_id = t.term_id
INNER JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id =
tt.term_taxonomy_id WHERE tt.taxonomy IN ('category') AND tr.object_id IN (3)
ORDER BY t.name ASC made by require, require_once, include, get_footer,
locate_template, load_template, require_once, dynamic_sidebar,
call_user_func_array, widget_rrm_recent_posts, RecentPosts->execute,
ppl_expand_template, otf_categorylinks, get_the_category, wp_get_object_terms
 
[05-Jan-2010 09:50:42] WordPress database error Error on delete of
'C:\Windows\TEMP\#sql17e0_1b0_0.MYD' (Errcode: 13) for query  SELECT
SQL_CALC_FOUND_ROWS  wp_posts.* FROM wp_posts  INNER JOIN wp_term_relationships
ON (wp_posts.ID = wp_term_relationships.object_id) INNER JOIN wp_term_taxonomy ON
(wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id)
WHERE 1=1  AND wp_term_taxonomy.taxonomy = 'category' AND
wp_term_taxonomy.term_id IN ('3') AND wp_posts.post_type = 'post' AND
(wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private') GROUP BY
wp_posts.ID ORDER BY wp_posts.post_date DESC LIMIT 0, 10 made by require, wp,
WP->main, WP->query_posts, WP_Query->query, WP_Query->get_posts

The important part here is "Errcode: 13", which is a file access error. The MySQL daemon process (mysqld.exe) randomly cannot access temporary tables it itself creates, which causes these errors and failed queries.

Digging Around

After looking around and finding nothing obvious, I tracked down a few forum posts mentioning the same issue.

Here is the gist – the problem is caused by an anti-virus program that is clearly not working properly.

The one mentioned on the forums is McAfee (big surprise, right? McAfee is a piece of junk – probably the worst anti-virus I've ever tried). In my case, however, it was the recently installed freeware security program from Microsoft called Microsoft Security Essentials, highly praised but problematic in this case nonetheless.

After thinking about it, I am confident that these security programs don't actually purposely prohibit access to the files MySQL creates. Instead, they lock these files for the duration of the check, so that the system doesn't get infected before they are approved. If you notice, the problems are related to temporary tables, created by MySQL on the fly. MySQL probably has a very short access timeout for these files, for performance reasons, and because it doesn't get this access fast enough, it considers it a failure (file deletions are failing, as you can see in the log).

The Solution

Now onto fixing the problem. The solution is to have Microsoft Security Essentials, in my case, or whatever your security program may be ignore these files.

You can block the whole Temp directory from being checked. It is not a good idea, as viruses can trickle down to that location and bypass your anti-virus:

Instead, you should just ignore by file extension: *.MYI and *.MYD. MySQL uses files with these extensions for its MyISAM table types. Using this approach is obviously safer as it doesn't single out a directory and instead targets specific files:

After I applied either of these exclusions, all MySQL Error 13 problems went away immediately.

Conclusion

The intermittent Error 13 problem on Windows is caused by 2 otherwise legitimate processes which, when mixed together, end up breaking MySQL.

Is this entirely the fault of the antivirus programs? Inadvertently, perhaps so.

Could MySQL be a bit smarter in this scenario? Perhaps so as well.

What do you, MySQL pros, think?

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My fiancée Emilie has had her Palm Pre for about 2 weeks now, and one specific problem that started showing up last week has been incredibly annoying, causing us all kinds of trouble.

After Emilie got the phone, she added 3 email accounts – Gmail, Hotmail, and Yahoo. One day, after sending an email through the Pre, a popup showed up that said "Error sending" followed by the subject of that specific email. Swiping the error away didn't help – it just came back 5 minutes later. In fact, it has been coming back every 5 minutes of every day since, lighting up the screen each time. Thus, not only it was annoying, but it was running down the battery like crazy – a full charge lasted between 1/2 and 3/4 of the day with very mild usage.

I deleted the problematic message from the Outbox a long time ago. The error didn't disappear and kept popping up. Additionally, whichever Outbox clicking on the annoying popup led to was having trouble refreshing, even though it wouldn't display what the error actually was – just a yellow exclamation sign would show up. Refreshing the folder didn't help and would take an unusually long time.

Well, finally, I got sick of waiting for Palm to update its OS with possible fixes and set out to find one myself.

Turns out a ton of people are having the same issue, as evident in all Palm Pre forums. For example, Palm.com forum or Precentral.net forum. I really didn't like the common suggestion to delete and re-add the problematic account because

• that just most likely temporarily pushes the problem back as I'm sure it would come back again to haunt me
• this could potentially erase or disconnect all contacts associated with that account
• my engineering mind would be left puzzled
• I wasn't sure which account was having the problem (later it turned out the culprit was Yahoo)

Surprisingly, I found the clue that led me to the solution on Yahoo Answers – yeah, that place where nothing intelligent is allowed to exist (with certain exceptions).

The Solution

To make a long story short, Pre messed up Yahoo's outgoing mail settings. My particular problem was the SMTP (that's the outgoing mail server) port was set to 995, which is in fact an incoming POP3 mail server port. I don't know how it happened or if it even worked in the first place but the fact is: the right outgoing port for secure (SSL) SMTP connections is 465. Also, for some reason the SMTP username was blank but the password was filled in. WTF, Pre?

When I changed SMTP port to 465 and entered the username, as specified in that Yahoo Answers post (without the @yahoo.com part), the error message went away and the Outbox refreshed just fine. BTW, my Pre has the incoming mail server set to POP3, while the Yahoo Answers post was set to IMAP – again, why the differences? I'd frankly prefer IMAP anyway.

To get to your mail account settings, open up your email application, go to the Email menu in Pre's top left corner, tap Preferences & Accounts, then tap the offending account, scroll down, and tap Change Login Settings. When you are done, just swipe back (half swipe from right to left in the gesture area). Here's a handy screenshot I took of the relevant area:

->

If you are experiencing the same symptoms, check ALL your mail settings, not just the ones I mentioned. Who knows what else your Pre may have messed up?

Update: if you are having trouble sending your mail while on WiFi only, it is possible that your router is blocking the needed ports. Try to edit the router configuration and open the ports used by your Pre's mail configuration – hopefully the problem will be solved.

Conclusion

Palm, are you hearing us? We are not happy with the bugs and the unhelpful error messages (or lack thereof altogether)! 3 measly updates in the last 2 months is quite pathetic. I hope you are working on a much bigger update behind the scenes.

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Every time I have to deal with svn:externals in SVN, I forget the command line syntax. Every single damn time. Normally, I use SVN GUI clients, such as SmartSVN, which make it very simple to add an svn:externals property. But for command line, it always takes looking at 25 different sites on google, which are all incredibly unhelpful for this question for some reason. Trying "svn help propset" on the command line was bloated and equally useless.

So this time I needed to write it down and make sure everyone who needed help with svn:externals would find exactly what they need here. I hope this page will soon come up on top of all the unhelpful results on google for "propset svn:externals" and other related queries.

The Problem

I want to set a simple svn:externals property in one of my project's directories, lets say 'plugins' (talking about WordPress here). The outcome would be a directory called 'akismet' within 'plugins' that points to a remote svn url.

Various combinations of trying to do it produced pathetic results, like

svn propset svn:externals akismet http://plugins.svn.wordpress.org/akismet/trunk
svn: Setting property on non-local target 'http://plugins.svn.wordpress.org/akismet/trunk' needs a base revision

svn propset svn:externals . akismet http://plugins.svn.wordpress.org/akismet/trunk
svn: Error parsing svn:externals property on 'akismet': '.'

svn propset svn:externals akismet http://plugins.svn.wordpress.org/akismet/trunk akismet
svn: Setting property on non-local target 'http://plugins.svn.wordpress.org/akismet/trunk' needs a base revision

The Solution

Finally, thanks to this post, I found the right command:

svn propset svn:externals 'akismet http://plugins.svn.wordpress.org/akismet/trunk' .
property 'svn:externals' set on '.'

Note that dot at the end of the command and the quotes around the directory name and url.

Now commit via

svn commit

and then

svn up
Fetching external item into 'akismet'
A    akismet/akismet.gif
A    akismet/akismet.php
A    akismet/readme.txt
Updated external to revision 127962.
 
Updated to revision 16.

There, was it that hard, forum gurus and blog fiends?

Edit: in order to set multiple directory/url pairs in a single svn:externals property, you should put the individual dir/url pairs into a file (let's call it 'svn.externals'), like so

akismet http://svn.wp-plugins.org/akismet/trunk
all-in-one-seo-pack http://svn.wp-plugins.org/all-in-one-seo-pack/trunk

and then apply the property using

svn propset svn:externals -F svn.externals .

You should also just check in 'svn.externals' to easily keep track of it.

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rcapache2 restart
/usr/sbin/httpd2-prefork: symbol lookup error: /usr/sbin/httpd2-prefork: undefined symbol: apr_ldap_ssl_init
Starting httpd2 (prefork) /usr/sbin/httpd2-prefork: symbol lookup error: /usr/sbin/httpd2-prefork: undefined symbol: apr_ldap_ssl_init
 
The command line was:
/usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -DSSL
                                                                      failed

So I tried reinstalling libapr and apache2-utils related stuff with no luck. ldconfig didn't help either. It's not until I looked at /usr/lib and relinked a few things that it started working. What the hell, SUSE?

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/usr/lib # l libapr*
-rw-r--r-- 1 root root 239306 2007-09-21 23:41 libapr-1.a
-rw-r--r-- 1 root root    821 2007-09-21 23:41 libapr-1.la
lrwxrwxrwx 1 root root     17 2008-07-30 00:21 libapr-1.so -> libapr-1.so.0.2.9*
lrwxrwxrwx 1 root root     18 2008-07-30 00:21 libapr-1.so.0 -> libapr-1.so.0.2.12*
-rwxr-xr-x 1 root root 543841 2008-07-29 23:47 libapr-1.so.0.2.12*
-rwxr-xr-x 1 root root 148372 2007-09-21 23:41 libapr-1.so.0.2.9*
-rw-r--r-- 1 root root 156300 2007-09-23 13:33 libaprutil-1.a
-rw-r--r-- 1 root root    912 2007-09-23 13:33 libaprutil-1.la
lrwxrwxrwx 1 root root     21 2008-07-30 00:22 libaprutil-1.so -> libaprutil-1.so.0.2.9*
lrwxrwxrwx 1 root root     22 2008-07-30 00:21 libaprutil-1.so.0 -> libaprutil-1.so.0.2.12*
-rwxr-xr-x 1 root root 291520 2008-07-29 23:47 libaprutil-1.so.0.2.12*
-rwxr-xr-x 1 root root  98148 2007-09-23 13:33 libaprutil-1.so.0.2.9*
 
/usr/lib # ln -sf libaprutil-1.so.0.2.9 libaprutil-1.so.0
/usr/lib # ln -sf libapr-1.so.0.2.9 libapr-1.so.0
 
/usr/lib # l libapr*
-rw-r--r-- 1 root root 239306 2007-09-21 23:41 libapr-1.a
-rw-r--r-- 1 root root    821 2007-09-21 23:41 libapr-1.la
lrwxrwxrwx 1 root root     18 2008-07-30 00:34 libapr-1.so -> libapr-1.so.0.2.9*
lrwxrwxrwx 1 root root     18 2008-07-30 00:21 libapr-1.so.0 -> libapr-1.so.0.2.9*
-rwxr-xr-x 1 root root 543841 2008-07-29 23:47 libapr-1.so.0.2.12*
-rwxr-xr-x 1 root root 148372 2007-09-21 23:41 libapr-1.so.0.2.9*
-rw-r--r-- 1 root root 156300 2007-09-23 13:33 libaprutil-1.a
-rw-r--r-- 1 root root    912 2007-09-23 13:33 libaprutil-1.la
lrwxrwxrwx 1 root root     21 2008-07-30 00:35 libaprutil-1.so -> libaprutil-1.so.0.2.9*
lrwxrwxrwx 1 root root     21 2008-07-30 00:35 libaprutil-1.so.0 -> libaprutil-1.so.0.2.9*
-rwxr-xr-x 1 root root 291520 2008-07-29 23:47 libaprutil-1.so.0.2.12*
-rwxr-xr-x 1 root root  98148 2007-09-23 13:33 libaprutil-1.so.0.2.9*
 
/usr/lib # rcapache2 restart
Syntax OK
Shutting down httpd2 (waiting for all children to terminate)          done
Starting httpd2 (prefork)                                             done

Voila, apache starts now. Grrr, why linker, why??

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