The following approach is not entirely satisfying because technically for biblatex all entries will have been \(no)cited, this leads to biblatex applying disambiguation techniques it would not have to use.
The main idea is to use a sourcemap restricted to \jobname-resource2.bib
\DeclareSourcemap{
\maps[datatype=bibtex]{
\map{
\perdatasource{\jobname-resource2.bib}
\step[fieldset=keywords, fieldvalue={, nocitethis}, append]
}
}
}
to add a keyword nocitethis to all the entries in that file.
We also define \bibcheck
\defbibcheck{mynocite}{%
\ifboolexpr{test {\ifciteseen} or test {\ifkeyword{nocitethis}}}
{}
{\skipentry}
}
This check will only print entries in the bibliography that either were cited before or have the specific keyword nocitethis that only entries from \jobname-resource2.bib have.
It remains to issue a \nocite{*} (so technically all entries are \nocited and processed by biber).
You will have to use the bibcheck in the bibliography
\printbibliography[check=mynocite]
We also will need to load biblatex with citetracker enabled in order for \ifciteseen to work
\usepackage[backend=biber,style=authoryear,citetracker=true]{biblatex}
MWE
\RequirePackage{filecontents}
\begin{filecontents*}{\jobname-resource1.bib}
@article{A2014,
author={First Author},
journal={Journal A},
title={First Paper},
note = {should appear in bib, because it was cited},
year={2014}
}
@article{D2014,
author={First Author},
journal={Journal A},
title={First Paper},
note = {should not be seen in bib},
year={2014}
}
\end{filecontents*}
\begin{filecontents*}{\jobname-resource2.bib}
@article{B2014,
author={Another Author},
journal={Journal B},
title={Second Paper},
note = {should appear in bib, b/c it is in \jobname-resource2 and nocite was issued},
year={2014}
}
@article{C2014,
author={Next Author},
journal={Journal C},
title={Third Paper},
note = {should appear in bib, b/c it is in \jobname-resource2 and nocite was issued},
year={2014}
}
\end{filecontents*}
\documentclass{article}
\usepackage[backend=biber,style=authoryear,citetracker=true]{biblatex}
\addbibresource{\jobname-resource1.bib}
\addbibresource{\jobname-resource2.bib}
\DeclareSourcemap{
\maps[datatype=bibtex]{
\map{
\perdatasource{\jobname-resource2.bib}
\step[fieldset=keywords, fieldvalue={, nocitethis}, append]
}
}
}
\defbibcheck{mynocite}{%
\ifboolexpr{test {\ifciteseen} or test {\ifkeyword{nocitethis}}}
{}
{\skipentry}
}
\nocite{*}
\begin{document}
This is a citation \cite{A2014}
\printbibliography[check=mynocite]
\end{document}

You will notice that there is a "(2014a)" but no "(2014b)", for Biber "(2014b)" exists - it is D2014 - and has been cited (because of \nocite{*}), we just suppress it in the bibliography via our check.
\nocite{key}an option for you? (Probably not) – moewe Apr 08 '14 at 11:51biblatexto distinguish the two bibliography sources (viakeywordsor the like), but it seems to be quite hard to makebiblatex\nocitea lot of entries but not all. – moewe Apr 08 '14 at 13:27biblatexis that it is only able to see the entries once they are in the.bblfile, but in order for an entry to get into the.bblfile it will have to be\cited or\nocited. – moewe Apr 08 '14 at 13:54biblatexbugtracker. – moewe Apr 11 '14 at 05:39