为什么尝试设置客户端变量导致coldfusion-out.log中的“字符串或二进制数据将被截断”消息？

Question

If I try and set a client variable, by just doing a simple <cfset Client.X = 0 /> in onRequestStart, the request takes over a second (rather than mere milliseconds), and the following is output in coldfusion-out.log :

Aug 22, 2013 15:51:54 PM Information [ajp-bio-8012-exec-9] - [Macromedia][SQLServer JDBC Driver][SQLServer]String or binary data would be truncated.
Aug 22, 2013 15:51:55 PM Information [ajp-bio-8012-exec-9] - client variable JDBC STORE - retry 1
Aug 22, 2013 15:51:55 PM Information [ajp-bio-8012-exec-9] - [Macromedia][SQLServer JDBC Driver][SQLServer]String or binary data would be truncated.
Aug 22, 2013 15:51:55 PM Information [ajp-bio-8012-exec-9] - client variable JDBC STORE - retry 2
Aug 22, 2013 15:51:55 PM Information [ajp-bio-8012-exec-9] - [Macromedia][SQLServer JDBC Driver][SQLServer]String or binary data would be truncated.
Aug 22, 2013 15:51:55 PM Information [ajp-bio-8012-exec-9] - client variable JDBC STORE - retry 3
Aug 22, 2013 15:51:55 PM Information [ajp-bio-8012-exec-9] - [Macromedia][SQLServer JDBC Driver][SQLServer]String or binary data would be truncated.
Aug 22, 2013 15:51:55 PM Warning [ajp-bio-8012-exec-9] - Failed to store CLIENT variables to datasource mydsn - [Macromedia][SQLServer JDBC Driver][SQLServer]String or binary data would be truncated.

As per the message, the variable doesn't get stored - but I'm not sure why it thinks anything would be truncated - it's not exactly a lot of data.

I'm pretty sure this has been working fine previously, but I'm not sure when it might have started playing up (I'd been doing work involving remote http requests, so wouldn't have noticed an extra second during that).

If I remove the client.x line, it responds immediately and doesn't log the warning.

Similarly, if I change the storage mechanism for client variables to either cookie or registry, the issue doesn't occur.

I've tried deleting the CDATA and CGLOBAL tables and re-assigning the datasource to let them be recreated, but this hasn't had an effect.

Answer 1

Just as I was about to post the question I figured out what it was, so to help anyone else experiencing the same problem I'll go ahead and answer too...

The error was referring to the app column.

This is created as a char(64), but for this application the name is generated based on a couple of factors which resulted in it ending up as 95 characters long.

I edited the column in the database to char(255) and the problem goes away.