6075 Tagging

One of my favs from the kilted master himself, Robbie B. Served as inspiration to another of my favs Johnny Steinbeck: 

Wee, sleeket, cowran, tim’rous beastie,

O, what a panic’s in thy breastie!

Thou need na start awa sae hasty,

          Wi’ bickerin brattle!

I wad be laith to rin an’ chase thee

          Wi’ murd’ring pattle!

I’m truly sorry Man’s dominion

Has broken Nature’s social union,

An’ justifies that ill opinion,

          Which makes thee startle,

At me, thy poor, earth-born companion,

          An’ fellow-mortal!

I doubt na, whyles, but thou may thieve;

What then? poor beastie, thou maun live!

A daimen-icker in a thrave

          ’S a sma’ request:

I’ll get a blessin wi’ the lave,

          An’ never miss ’t!

Thy wee-bit housie, too, in ruin!

It’s silly wa’s the win’s are strewin!

An’ naething, now, to big a new ane,

          O’ foggage green!

An’ bleak December’s winds ensuin,

          Baith snell an’ keen!

Thou saw the fields laid bare an’ waste,

An’ weary Winter comin fast,

An’ cozie here, beneath the blast,

          Thou thought to dwell,

Till crash! the cruel coulter past

          Out thro’ thy cell.

That wee-bit heap o’ leaves an’ stibble

Has cost thee monie a weary nibble!

Now thou’s turn’d out, for a’ thy trouble,

          But house or hald,

To thole the Winter’s sleety dribble,

          An’ cranreuch cauld!

But Mousie, thou art no thy-lane,

In proving foresight may be vain:

The best laid schemes o’ Mice an’ Men

          Gang aft agley,

An’ lea’e us nought but grief an’ pain,

          For promis’d joy!

Still, thou art blest, compar’d wi’ me!

The present only toucheth thee:

But Och! I backward cast my e’e,

          On prospects drear!

An’ forward tho’ I canna see,

          I guess an’ fear!

Capture the Flag

WHo can get an ad to show up here?

Googleversary

One year ago tomorrow I started my job as a Software Engineer for Google. It has been an amazing year so far, and I can't wait to get back to work tomorrow. I'm not supposed to reveal all the engineering trades secrets, but there are a few things that I can talk about that have really impressed me.

• One codebase. The vast majority of Google's engineers check their code into a single trunk. I am continually amazed that so many engineers can work together without stepping on each other's toes.
• Code reviews. Almost every single line of code that is committed to trunk is code-reviewed. While it's true that bugs do make it into the codebase, these code-reviews keep a consistent style while preventing errors and cross-functional issues.
• Craftsmanship. Everyone here seems to have it, and it is contagious. Even working with simple code, I find myself writing better, cleaner code.
• Engineering happiness. When you have this many engineers, every small improvement to the engineering process pays huge dividends. Because of this, Google spends some serious time an energy improving the engineering process.

This is just a quick sampling of what makes Google, Google. For more reading, there are some good explanations on the eng-tools blog (http://google-engtools.blogspot.com/)

Techstumbler started as a way for me to catalog all of the tech problems that I "stumbled" across, but couldn't find a good answer for elsewhere. Since joining Google, my output here has basically gone to zero for two reasons. First, while I was swimming in the deep-end for C#, .NET, Powershell in my previous job, I've had to strap on my swimmies and resign myself to shallower waters in the Java/Linux stack. Second, many, many of the tech problems I run into now relate to the Google infrastructure itself, which I can't really talk about, and wouldn't be useful to anyone not on that stack anyway.

All that said, I would like to start writing here again. I might try to post some thoughts about some of my other interests, but I'll try to keep things for the tech audience. We'll see what I come up with.

Loading Remote Assemblies in Powershell with .NET 4

We recently updated our entire codebase to .NET 4.0 from 3.5. There are plenty of blog posts about that process in general, so I'm going to keep this one specific to our Powershell deployment scripts.

We build our code to a central server and then use Powershell to install those build on our Development server. The upgrade to .NET 4 caused 2 problems with Powershell when we called [Reflection.Assembly]::LoadFile()

First:
Powershell by default runs in .NET 2.0. When we tried to load our new 4.0 assemblies, we got this error:


Exception calling "LoadFile" with "1" argument(s): "Could not load file or assembly 'file://\\buildServer\Application\assembly.dll' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded."
At C:\Scripts\Deployment\Deploy.ps1:XX char:XX
+ $assembly = [Reflection.Assembly]::LoadFile <<<< ($file); + CategoryInfo : NotSpecified: (:) [], ParentContainsErrorRecordException + FullyQualifiedErrorId : DotNetMethodException

We need to tell Powershell to run in .NET 4.0 mode. To do that we need to create an app.config file for Powershell. In our case the file was created here: C:\WINDOWS\system32\windowspowershell\v1.0\powershell.exe.config, but YMMV based on Powershell's location. The new powershell.exe.config file looks like this:


<?xml version="1.0"?>
<configuration>
 <startup useLegacyV2RuntimeActivationPolicy="true">
  <supportedruntime version="v4.0.30319"/>
  <supportedruntime version="v2.0.50727"/>
 </startup>
</configuration>

Now Powershell can run with both 2.0 and 4.0 assemblies.

Second:
The security features are a bit different when running 2.0 vs 4.0. This difference caused a problem when running assemblies from our Build server on our Development server:


Exception calling "LoadFile" with "1" argument(s): "An attempt was made to load an assembly from a network location which would have caused the assembly to be sandboxed in previous versions of the .NET Framework. This release of the .NET Framework does not enable CAS policy by default, so this load may be dangerous. If this load is not intended to sandbox the assembly, please enable the loadFromRemoteSources switch. See http://go.microsoft.com/fwlink/?LinkId=155569 for
more information."
At C:\Scripts\Deployment\Deploy.ps1:XX char:XX
+ $assembly = [Reflection.Assembly]::LoadFile <<<< ($file); + CategoryInfo : NotSpecified: (:) [], ParentContainsErrorRecordException + FullyQualifiedErrorId : DotNetMethodException

Now we simply add the loadFromRemoteSources switch to the powershell.exe.config file we just created so that the entire file looks like this:

<?xml version="1.0"?>
<configuration>
 <startup useLegacyV2RuntimeActivationPolicy="true">
  <supportedruntime version="v4.0.30319"/>
  <supportedruntime version="v2.0.50727"/>
 </startup>
<runtime>
 <loadfromremotesources enabled="true"/>
</runtime>
</configuration>

Now we are successfully loading remote .NET 4.0 assemblies in Powershell. Hope this helps.

Safari User Agent Detection in JavaScript

Here's a quick snippit for detecting if a browser is Safari version 4 or 5. It works for both desktop and mobile (iPhone, iPod, iPad) versions.


function detectSafari45()
{
  var safariRegEx = /Mozilla\/5\.0 \([^\)]*\) AppleWebKit\/\d+\.\d+(\.\d+)? \(KHTML, like Gecko\) Version\/[45]\.\d+\.\d+( Mobile\/\w*)? Safari\/\d+\.\d+(\.\d+)?/i
  var match = safariRegEx.exec(navigator.userAgent);

  if (match !== null && match.length > 0)
  {
    return true;
  }
  return false;
}


Averaging Timespans in T-SQL

I'm doing some work with an operations queue. All of the operations are added to a small table on our SQL Server instance. We have a start_datetime and a stop_datetime for each operation. It took me a little time but here's a select statement for profiling the wait times for operations in our queue.


select
  CONVERT(VARCHAR(13),creation_date,120) as [hour],
  CONVERT(VARCHAR(8), max(stop_datetime - start_datetime), 108) as MaxWaitTime,
  CONVERT(VARCHAR(8), min(stop_datetime - start_datetime), 108) as MinWaitTime,
  CONVERT(VARCHAR(8), cast(avg(cast(stop_datetime - start_datetime as float)) as datetime), 108) as AvgWaitTime
from
  [OpQueue].[Op]
where
  start_datetime > '2011-05-07'
group by
  CONVERT(VARCHAR(13),start_datetime ,120)


Here are a few things to note.
This statement will spit out the min, max, and average running time for operations in the queue that start in the same hour.
The third argument for convert is pretty handy for DATETIMEs. Here is the page where it is described: http://msdn.microsoft.com/en-us/library/ms187928.aspx.
The AVG() function doesn't work for DATETIMEs, so we need to convert it to a float and then back again to get what we are looking for.

Here's the graph we ended up with.

Seems like it's time to invest in some more processing power.

Running Hudson from OS X: the .war.zip Fiasco

It took me a while to figure this out and maybe it's just because I'm not a java guy, but I couldn't figure out how to start the Hudson continuous integration tool on my Mac. I downloaded the 2.0.0 version from the Hudson site (http://hudson-ci.org/). The file was hudson-2.0.0.war.zip. The instructions say to run

java -jar hudson-2.0.0.war

to start up the service. I unzipped the file and ended up with a bunch of .class files and no .war. Ah, looks like I also unzipped the .war file. So then I found this nice post (http://superuser.com/questions/159260/in-mac-os-x-how-can-i-unzip-a-zip-file-without-unzipping-its-contents) on how to unzip a file without unzipping its contents. Now I have a

hudson-2.0.0.war/

directory. I ran

$ java -jar hudson-2.0.0.war
Invalid or corrupt jarfile hudson-2.0.0.war

Hmm, not sure what to do next. Somewhere in my search I read that a .war is basically just a zip file. So I tried

$ java -jar hudson-2.0.0.war.zip

on the original file, which worked. I renamed hudson-2.0.0.war.zip

$ mv hudson-2.0.0.war.zip hudson-2.0.0.war

and I was off and running.

So I hope this helps some other java n00bs who may have run into this. The moral of the story is .war == .zip

Moving Replicated FullText Index in SQL Server

We needed to move the location of our full text index (FTI) on a subscriber. I thought this would be a pain because the replication, but it turns out to be pretty straightforward. Here's the system I am working with:

SQL Server 2005
Transactional Replication with an Updateable Subscriber.

Here are the steps I took:


0. Make sure you have appropriate backups.
1. Point all of the apps to the Publisher because we will need to take the Subscriber offline.
2. On the Subscriber, open the synchronization status by right-clicking on Replication->Local Subscriptions-> ans selecting View Synchronization Status.
3. Stop the Synchronization Service. (This really just pauses updates).
4. On the Subscriber run SELECT name FROM sys.database_files WHERE type_desc = 'FULLTEXT'; to get the name of the FTI.
5. On the Subscriber run ALTER DATABASE [DB_NAME] SET OFFLINE;
6. Move the FTI where to it's new home.
7. On the subscriber run ALTER DATABASE [DB_NAME] MODIFY FILE (Name=[FTI_NAME], Filename = "'new/location/on/disk/');
8. On the Subscriber run ALTER DATABASE [DB_NAME] SET ONLINE;
9. Start the Sync Service in View Synchronization Status.

That should be it. Hope this helps.

T-SQL Query: Tables Without a Primary Keys

I used this when I was setting up a Transactional Replication system on SQL Server. I needed to figure out which tables did not have primary keys assigned.


select s.name+'.'+ t.name
from
  sys.schemas s
  join sys.tables t on s.schema_id = t.schema_id
  left join sys.indexes i on i.object_id = t.object_id and
                             i.is_primary_key = 1
where i.name is null
order by (s.name+'.'+ t.name) asc;


Great Post on SQL Server Stored Procedure Variables

It took me a while to find this about using variables in the TOP clause of a MSSQL stored prodedure. This post answered all my questions:

http://sqlserver2000.databases.aspfaq.com/how-do-i-use-a-variable-in-a-top-clause-in-sql-server.html

Here's the best part


CREATE PROCEDURE dbo.getFoo
  @top INT 
AS
  BEGIN
    SET ROWCOUNT @top

    SELECT foo
      FROM blat
      ORDER BY foo DESC

    -- never forget to set it back to 0!
    SET ROWCOUNT 0
  END
GO


Programmaticly Changing the File Attribute of an App.config File.

The requirement for this assignment was to use a command line argument to change the settings of a C# console application. I didn't want to compile the settings into the app itself, but to use an app.config file instead. Here's how it works:


public static bool SetEnvironment(string env)
{
  string configFilePath = string.Empty;

  env = env.ToLowerInvariant();
  switch (env)
  {
    case "dev":
       configFilePath = @"Config\Dev.config";
       break;
    case "prod":
       configFilePath = @"Config\Prod.config";
       break;
    default:
       return false;
  }

  try
  {
    System.Configuration.Configuration config =
       ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

    AppSettingsSection appSetSec = config.AppSettings;
    appSetSec.File = configFilePath;
    config.Save(ConfigurationSaveMode.Modified);
    ConfigurationManager.RefreshSection("appSettings");
  }
  catch (Exception ex)
  {
    OfflineDemoTool.WriteError(ex.Message);
    return false;
  }

  return true;
}



One thing that I forgot to do was to make sure that the Config\Dev.config and Config\Prod.config files were set to "Copy if newer" in their properties list, otherwise they won't be copied to the output directory.

Most of this comes straight from the MSDN article found here: http://msdn.microsoft.com/en-us/library/system.configuration.appsettingssection.aspx

Windows Commands with Arguments in Powershell

I have been trying to write a simple PowerShell script that runs (invokes?) MySqlDump.exe for two days. PowerShell syntax for running commands with arguments is not obvious and I wasn't able to find it documented anywhere. While this case is specific to mysqldump, it can be applied to any command line executable with multiple arguments. The trick is to create an array of the arguments and use that as the second "argument" for the ampersand (&) call operator. Here's what my final example looked like:



[string]$pathToExe = "C:\MySQL\MySQL Server 5.1\bin\mysqldump.exe";
[string]$user = "myUser";
[string]$password = "myPass";
[string]$dbName = "myDB";
[Array]$arguments = "-u", $user, "--password=$password", $dbName;

& $pathToExe $arguments | Out-File -FileName "out.sql";




So there you have it. That's how to run an executable with spaces and arguments from PowerShell.

While this article from PowerShell.com didn't answer my questions, I thought it was pretty useful and relevent:

http://powershell.com/cs/blogs/ebook/archive/2009/03/30/chapter-12-command-discovery-and-scriptblocks.aspx

Changing aspnet_wp user in IIS 5.1

It's possible that no one will ever have to work with IIS 5.1 in XP again, but here you go just in case:

We needed the asp.net worker process (aspnet_wp.exe) to access a share on a remote machine. By default the "Netowrk Service" runs aspnet_wp and that user doesn't have access to remote shares. The way to change this is by changing the "processModel" attribute in your machine.config file (c:\windows\microsoft.net\framework\v2*\config\machine.config).

Mine ended up looking something like this:

<system.web>
<processModel userName="DOMAIN\username" password="password" autoConfig="true">
</processModel>
...
</system.web>


Just make sure to restart IIS for the changes to take effect.

Powershell Diff Directory

I wanted to create a file diff between two different directories. Unfortunately, the Copy-Item CmdLt will not (as far as I know) create the directory structure while copying. This is a bummer. I wanted to keep all of the files in the pipe as opposed to to getting all the files first because of the number of files in the directory structure. Here's what I cam up with



$fromDir = "C:\FromDir";
$toDir = "C:\ToDir";
$diffDir = "C:\DiffDir";


Get-ChildItem -Recurse -Path $fromDir | % {
if ((Test-Path (Join-Path -Path $toDir -ChildPath ([string]$_.FullName).Replace($fromDir, ""))) -eq $false)
{
if ((Test-Path (Join-Path -Path $diffDir -ChildPath ([string]$_.Directory).Replace($fromDir, ""))) -eq $false)
{
New-Item -Type "Directory" -Path (Join-Path -Path $diffDir -ChildPath ([string]$_.Directory).Replace($fromDir, ""));
}
Copy-Item -Recurse -Force $_.FullName -Destination (Join-Path -Path $diffDir -ChildPath ([string]$_.FullName).Replace($fromDir, ""));
}
};



As always, if anyone know a better way to do this, let me know.

Powershell Rename-Item vs Copy-Item: Changing file names to upper case

I needed recursively change all file and sub-directory names in a directory from mixed case to upper case. To me, this felt like a problem for PowerShell, but maybe I was wrong. Here was my first attempt:



Get-ChildItem -Recurse -Path "C:\media" | % {Rename-Item $_.FullName -NewName ([string]$_.Name).ToUpper()};


However, I received the following error:


Rename-Item : Source and destination path must be different.


So it looks like PowerShell refused to rename file1 to FILE1, because it thinks that they are the same file. In order to get around this I ended up copying the entire tree, and even that command isn't particularly elegant:


Get-ChildItem -Recurse -Path "C:\media" | % {Copy-Item -Force $_.FullName ([string]$_.FullName).Replace("C:\media", "C:\MEDIA2").ToUpper()};


If there is a better way to do this, I'd love to know.

XPlanner Authentication with NTLM

I spent most of the day setting up XPlanner and the documentation seemed to be lacking in a few spots. I'll go over the caveats I stumbled on.

The XPlanner install was happening on the lone linux box (Fedora 8) on an NT domain. The box was almost completely empty so I had to install java first. I chose to install the jsdk 1.4.2 even though that version's is EOL'd. XPlanner hasn't been updated in a while (since 2006) and I didn't want to mess w/ a new version of the sdk.

I upacked and installed the "standalone" version of XPlanner 0.7b7. So far so good. I was immediately able to use the default username/password to login.

The hardest part was figuring out how to authenticate based on our NT credentials. Most of the configuration occurs in the xplanner-0.7b7-standalone/webapps/ROOT/WEB-INF/classes/xplanner.properties file.

Here's how I was able to get the NT authentication to work. In the xplanner.properties file, find the authentication strings:


#
# XPlanner security configuration
#
xplanner.security.login[0].module=com.technoetic.xplanner.security.module.XPlannerLoginModule
xplanner.security.login[0].name=XPlanner
xplanner.security.login[0].option.userIdCaseSensitive=true
xplanner.security.login[0].option.debug=true

#xplanner.security.login[1].module=com.technoetic.xplanner.security.module.jndi.JNDILoginModule
#xplanner.security.login[1].name=JNDI
#xplanner.security.login[1].option.userIdCaseSensitive=false
#xplanner.security.login[1].option.debug=true
#xplanner.security.login[1].option.connectionURL=
#xplanner.security.login[1].option.connectionName=cn=
#xplanner.security.login[1].option.connectionPassword=
#xplanner.security.login[1].option.digest=SHA
#xplanner.security.login[1].option.userPattern=
#xplanner.security.login[1].option.userPassword=
#xplanner.security.login[1].option.authentication=simple
#xplanner.security.login[1].option.derefAliases=never
#xplanner.security.login[1].option.userSearch=cn={0}
#xplanner.security.login[1].option.userSubtree=true
#xplanner.security.login[1].option.roleBase=
#xplanner.security.login[1].option.roleName=
#xplanner.security.login[1].option.roleSearch=(uniqueMember={0})

# NTLM login module
#xplanner.security.login[2].module=com.technoetic.xplanner.security.module.ntlm.NtlmLoginModule
#xplanner.security.login[2].name=NTLM
#xplanner.security.login[2].option.userIdCaseSensitive=false
#xplanner.security.login[2].option.domain=DOMAIN
#xplanner.security.login[2].option.controller=CONTROLLER


To use the NTLM module, comment out the first set to security strings, uncomment the NTLM strings, and change the NTLM array index to 0. Here's how my file looked after I finished.


#
# XPlanner security configuration
#
#xplanner.security.login[0].module=com.technoetic.xplanner.security.module.XPlannerLoginModule
#xplanner.security.login[0].name=XPlanner
#xplanner.security.login[0].option.userIdCaseSensitive=true
#xplanner.security.login[0].option.debug=true

#xplanner.security.login[1].module=com.technoetic.xplanner.security.module.jndi.JNDILoginModule
#xplanner.security.login[1].name=JNDI
#xplanner.security.login[1].option.userIdCaseSensitive=false
#xplanner.security.login[1].option.debug=true
#xplanner.security.login[1].option.connectionURL=
#xplanner.security.login[1].option.connectionName=cn=
#xplanner.security.login[1].option.connectionPassword=
#xplanner.security.login[1].option.digest=SHA
#xplanner.security.login[1].option.userPattern=
#xplanner.security.login[1].option.userPassword=
#xplanner.security.login[1].option.authentication=simple
#xplanner.security.login[1].option.derefAliases=never
#xplanner.security.login[1].option.userSearch=cn={0}
#xplanner.security.login[1].option.userSubtree=true
#xplanner.security.login[1].option.roleBase=
#xplanner.security.login[1].option.roleName=
#xplanner.security.login[1].option.roleSearch=(uniqueMember={0})

# NTLM login module
xplanner.security.login[0].module=com.technoetic.xplanner.security.module.ntlm.NtlmLoginModule
xplanner.security.login[0].name=NTLM
xplanner.security.login[0].option.userIdCaseSensitive=false
xplanner.security.login[0].option.domain=DOMAIN
xplanner.security.login[0].option.controller=CONTROLLER


The NTLM module uses the local DB as a fall back, so any logins that you creaed locally that aren't in the Active Directory should still work.

JPEG Marker codes

I'm doing a bit of JPEG manipulation for a project and it took me longer than I would have liked to find a consise table of JPEG segment markers or frame markers or whatever you want to call them. Here's a C# enum with all the values. Hopefully that will save some typing for you.

        public enum JpegMarkers

        {

            // Start of Frame markers, non-differential, Huffman coding

            HuffBaselineDCT = 0xFFC0,

            HuffExtSequentialDCT = 0xFFC1,

            HuffProgressiveDCT = 0xFFC2,

            HuffLosslessSeq = 0xFFC3,




            // Start of Frame markers, differential, Huffman coding

            HuffDiffSequentialDCT = 0xFFC5,

            HuffDiffProgressiveDCT = 0xFFC6,

            HuffDiffLosslessSeq = 0xFFC7,




            // Start of Frame markers, non-differential, arithmetic coding

            ArthBaselineDCT = 0xFFC8,

            ArthExtSequentialDCT = 0xFFC9,

            ArthProgressiveDCT = 0xFFCA,

            ArthLosslessSeq = 0xFFCB,




            // Start of Frame markers, differential, arithmetic coding

            ArthDiffSequentialDCT = 0xFFCD,

            ArthDiffProgressiveDCT = 0xFFCE,

            ArthDiffLosslessSeq = 0xFFCF,




            // Huffman table spec

            HuffmanTableDef = 0xFFC4,




            // Arithmetic table spec

            ArithmeticTableDef = 0xFFCC,




            // Restart Interval termination

            RestartIntervalStart = 0xFFD0,

            RestartIntervalEnd = 0xFFD7,




            // Other markers

            StartOfImage = 0xFFD8,

            EndOfImage = 0xFFD9,

            StartOfScan = 0xFFDA,

            QuantTableDef = 0xFFDB,

            NumberOfLinesDef = 0xFFDC,

            RestartIntervalDef = 0xFFDD,

            HierarchProgressionDef = 0xFFDE,

            ExpandRefComponents = 0xFFDF,




            // App segments

            App0 = 0xFFE0,

            App1 = 0xFFE1,

            App2 = 0xFFE2,

            App3 = 0xFFE3,

            App4 = 0xFFE4,

            App5 = 0xFFE5,

            App6 = 0xFFE6,

            App7 = 0xFFE7,

            App8 = 0xFFE8,

            App9 = 0xFFE9,

            App10 = 0xFFEA,

            App11 = 0xFFEB,

            App12 = 0xFFEC,

            App13 = 0xFFED,

            App14 = 0xFFEE,

            App15 = 0xFFEF,




            // Jpeg Extensions

            JpegExt0 = 0xFFF0,

            JpegExt1 = 0xFFF1,

            JpegExt2 = 0xFFF2,

            JpegExt3 = 0xFFF3,

            JpegExt4 = 0xFFF4,

            JpegExt5 = 0xFFF5,

            JpegExt6 = 0xFFF6,

            JpegExt7 = 0xFFF7,

            JpegExt8 = 0xFFF8,

            JpegExt9 = 0xFFF9,

            JpegExtA = 0xFFFA,

            JpegExtB = 0xFFFB,

            JpegExtC = 0xFFFC,

            JpegExtD = 0xFFFD,




            // Comments

            Comment = 0xFFFE,




            // Reserved

            ArithTemp = 0xFF01,

            ReservedStart = 0xFF02,

            ReservedEnd = 0xFFBF

        };

eApps and yum

One of my new projects is hosted on eApps. While they've been great so far, I spent some time trying to get some real developer tools on my box using yum. The first problem was that php was failing with the following error:

PHP Warning: Module 'modulename' already loaded in Unknown on line 0

As it turns out that means that the xls package was included in the binary, and also being declared as a dynamic package. So, to fix this I commented out the following line in the /etc/php.d/xsl.ini:

;extension=xsl.so

Now on to yum itself. Doing any kind of yum update resulted in the following error:

Error: Missing Dependency: glibc-common = 2.3.4-2.36 is needed by package glibc-dummy-centos-4

After doing a bit of research, I found that the dummy-centos-4 package isn't really necessary if you're going to be upgrading your gcc libraries anyways so away it goes.

yum remove glibc-dummy-centos-4

After that I ran a full yum upgrade which worked just fine.

Stripping Accennts From Text With PHP

Most of the PHP string functions don't really work with UTF-8 encoded strings (http://bugs.php.net/bug.php?id=35520). I found this post on the Symfony forums that had a solution.

$text = iconv('UTF-8', 'ASCII//TRANSLIT', $text);

Done and done.

SQL Join with count

For the real estate site I've been working on, I needed to get a list of real estate offices and how many active listings they had on the MySQL DB we are using. I had a table of offices and a table of listings. I needed each office represented even if that office had no active listings. It seemed like an easy application of the left join command. Not quite as easy as I thought. Here's my first attempt:


SELECT
COUNT(listings.id), offices.id
FROM offices LEFT JOIN listings ON (offices.id = listings.office_id)
WHERE
listings.status = 1


However, this only returned office/count pair where the count was greater than 0. It seemed like the WHERE condition wasn't being applied correctly, like it was being applied AFTER the tables were joined. I wanted the WHERE condition to be applied to the listings table and then have the results joined to the offices table. So, here's the solution I found: in situations like this, the WHERE clause needed to be added to the ON clause in the LEFT JOIN like this:


SELECT
COUNT(listings.id), offices.id
FROM offices LEFT JOIN listings ON (offices.id = listings.office_id AND listings.status = 1)


Works like a charm.