PATINDEX will return the position of the XML in the row, and if your table contains millions of rows than it will take some time until you get the count.
There is a TEXTSIZE property, which by default is 64KB (i.e. 64,000). Check it on both databases via I belive SELECT @@TEXTSIZE and the way to set it is by...
As you said that the datatype is blob you will have to use the WRITETEXT FUNCTION to set the column values to NULL (which is a non-logging operation) via a...