Thanks for your answer! As mentioned, I'm aware of the problems with other characters like colons and dashes. I've just never run into any issues with dollar signs. And previously, before there was an official definition, I heard from several people that "valid Java identifiers" was a good rule of thumb – which would include dollar signs.
I'd just hoped that when there would be a definition (and it's of course very good and important that there now is one) it would more or less mirror that rule of thumb and also allow for dollar signs. Now it's a pretty tough call whether to use them or not. Cheers, Thomas On 2015-07-27 21:31, Erick Erickson wrote: > The problem has been that field naming conventions weren't > _ever_ defined strictly. It's not that anyone is taking away > the ability to use other characters, rather it's codifying what's always > been true; Solr isn't guaranteed to play nice with naming > conventions other than those specified on the page you > referenced, alphanumerics and underscores and _not_ starting > with numerics. > > The danger is that parsing the incoming URL can run into > "issues". Take for instance a colon. How would the parsing > process distinguish that from a field:value separator? Or a > hyphen when is that NOT and when is that part of a field > name? Periods are also interesting. You can specify some > params (e.g. facet params) with periods (f.field.prop=). No > guarantee has ever been made that a field _name_ with a > period won't confuse things. It happens to work, but that's > not by design, just like dollar signs. > > So you can use dollar signs, but there won't be any attempts > to support it if some component somewhere doesn't "do the > right thing" with it. And no guarantee that there aren't current > corner cases where that causes problems. And if it does cause > problems, support won't be added. > > Best, > Erick > > On Mon, Jul 27, 2015 at 10:42 AM, Thomas Seidl <re...@gmx.net> wrote: >> Hi all, >> >> I've used dollar signs in field names for several years now, as an easy >> way to escape "bad" characters (like colons) coming in from the original >> source of the data, and I've never had any problems. Since I don't know >> of any Solr request parameters that use a dollar sign as a special >> character, I also wouldn't know where one might occur. >> >> But while I remember that the "supported" format for field names was >> previously completely undocumented (and it was basically "almost >> anything is supported, but some things might not work with some >> characters"), I now read that for about a year there has been a strict >> definition/recommendation in the Solr wiki [1] which doesn't allow for >> dollar signs. >> >> [1] https://cwiki.apache.org/confluence/display/solr/Defining+Fields >> >> So, my question is: Is this just for an easier definition, or is there a >> real danger of problems when using dollar signs in field names? Or, >> differently: How "bad" of an idea is it? >> Also, where was this definition discussed, why was this decision >> reached? Is there really an argument against dollar signs? I have to say >> it is really very handy to have a character available for field names >> that is usually not allowed in programming language's identifiers (as a >> cheap escape character). >> >> Thanks in advance, >> Thomas >
