1. A computer-readable medium having computer executable instructions encoded thereon, the computer executable instructions executed by a processor to perform operations for long-query retrieval comprising: identifying a query file on which to base a query; performing decomposition comprising utilizing a probabilistic topic model to obtain a decomposed version of the query file, the decomposed version of the query file comprising: topic-related words; and file-specific words; creating a composite representation of the query file, the composite representation comprising: a vector of the topic-related words; and an index of a configurable number of file-specific words; based at least on the vector of the topic-related words, determining a topic corresponding to the query file; comparing the vector of the topic-related words of the query file to vectors of topic-related words of a plurality of files; selecting a candidate set of files from the plurality of files based at least on a ranking of closeness of proximity of the vectors of the topic-related words of the candidate set of files to the vector of the topic-related words of the query file; performing re-ranking of the files in the candidate set of files, the re-ranking comprising: comparing the index of the file-specific words of the query file to indexes of the file-specific words of the files in the candidate set of files; assigning scores to files in the candidate set of files based at least on calculated similarity of the indexes of the candidate set of files and the index of the query file; and returning a configurable number of the files from the candidate set of files having the highest scores.