You cannot use regular expressions as such, but you can use some similar (in concept and somewhat in format) match methods available in the graphic rendering URL API. There are several ways to “combine” in the target “bucket” (that is, between points).
Target Compliance
Asterisk Symbol *
An asterisk can be used to match ANY -zero or more-character (s) . It can be used to replace the entire bucket ( site.*.test ) or inside the bucket ( site.w*t.test ). Here is an example:
site.testing_server_2.requests_*.count
This will match site.testing_server_2.requests_failed.count, site.testing_server_2.requests_success.count, site.testing_server_2.requests_blah123.count, etc.
The character range [a-z0-9] matches
Matching a range of characters is used to match a single character ( site.w[0-9]t.test ) in the target bucket and is specified as a range or list. For example:
site.testing_server_[0-4].requests_failed.count
This will match at site.testing_server_0.requests_failed.count, site.testing_server_1.requests_failed.count, site.testing_server_2.requests_failed.count, etc.
List of values (group capture) {blah, test, ...} matches
Matching a list of values can be used to match any one in the list of values in a specified part of the target bucket.
site.testing_server_2.{triggers_unknown,requests_failed,core_network_bad_soap}.count
This will match site.testing_server_2.triggers_unknown.count, site.testing_server_2.requests_failed.count and site.testing_server_2.core_network_bad_soap.count. But nothing else, so site.testing_server_2.module_xyz_abc.count will not match.
Answer
Without knowing all of your bucket values, it is difficult to be surgical with an approach (possibly with a combination of matching options), so I recommend just going to the value of the list of values . This should allow you to get all the values in one - too long query. For example (and keep in mind that you will need to include all of your values):
summarize(site.testing_server_2.{triggers_unknown,requests_failed,core_network_bad_soap}.count,'1hour','sum')&format=json&from=-24hour
For more information, see Graphite Paths and Wildcards.