* Get derivation outputs from the database instead of the .drv file,

which requires more I/O.

src/libstore/store-api.hh

@@ -139,6 +139,9 @@ public:
        no deriver has been set. */
     virtual Path queryDeriver(const Path & path) = 0;
 
+    /* Query the outputs of the derivation denoted by `path'. */
+    virtual PathSet queryDerivationOutputs(const Path & path) = 0;
+    
     /* Query whether a path has substitutes. */
     virtual bool hasSubstitutes(const Path & path) = 0;