I had to update a Drupal 7 site recently and needed to change the field keys of a list field to be different values. This wasn't possible from within Drupal as it does a pre-check to make sure that the key doesn't already exist. If it finds any values present in the database with that key then it will reject the change. This is absolutely correct but causes a little bit of an issue when you need to update these values.
I was recently working on a module that contained a content type as a feature. When the module was enabled the hook_install() hook set up a collection of taxonomy terms which were used within the content type as a field. Whilst testing this out I realised that although the terms were installed correctly the default value of the field changed depending on which system the module was installed on. The reason for this was that the term ID was being used to pull out the default term from the database, which is the normal behaviour in Drupal.
Altering text in Drupal 7 is quite simple thanks to things like string overrides that allow you to replace all instances of a string throughout a site. If you want to change a single element on a single form then string overrides don't quite work, but using hook_form_alter() or hook_form_form-id_alter() allows you to manipulate any form in a Drupal site.
I have previously talked about enable custom field search in Wordpress, but that involved altering the main Wordpress files, which is a big no-no.
So is there an alternative? Well, yes, otherwise I wouldn't have bothered writing the post! To enable custom field (also called Wordpress metadata) searching you need to set up two things.
First you need to have created a custom field (or two) and added this to a number of posts.