Query an index¶
Usage¶
Benchmarks queries on a given index.
Usage: queries [OPTIONS]
Options:
-h,--help Print this help message and exit
-e,--encoding TEXT REQUIRED Index encoding
-i,--index TEXT REQUIRED Inverted index filename
-w,--wand TEXT WAND data filename
--compressed-wand Needs: --wand
Compressed WAND data file
--tokenizer TEXT:{english,whitespace}=english
Tokenizer
-H,--html UINT=0 Strip HTML
-F,--token-filters TEXT:{krovetz,lowercase,porter2} ...
Token filters
--stopwords TEXT Path to file containing a list of stop words to filter out
-q,--queries TEXT Path to file with queries
--terms TEXT Term lexicon
--weighted Weights scores by query frequency
-k INT REQUIRED The number of top results to return
-a,--algorithm TEXT REQUIRED
Query processing algorithm
-s,--scorer TEXT REQUIRED Scorer function
--bm25-k1 FLOAT Needs: --scorer
BM25 k1 parameter.
--bm25-b FLOAT Needs: --scorer
BM25 b parameter.
--pl2-c FLOAT Needs: --scorer
PL2 c parameter.
--qld-mu FLOAT Needs: --scorer
QLD mu parameter.
-T,--thresholds TEXT File containing query thresholds
-L,--log-level TEXT:{critical,debug,err,info,off,trace,warn}=info
Log level
--config TEXT Configuration .ini file
--quantized Quantized scores
--extract Extract individual query times
--safe Needs: --thresholds Rerun if not enough results with pruning.
Now it is possible to query the index. The command queries
treats each
line of the standard input (or a file if -q
is present) as a separate
query. A query line contains a whitespace-delimited list of tokens.
These tokens are either interpreted as terms (if --terms
is defined,
which will be used to resolve term IDs) or as term IDs (if --terms
is
not defined). Optionally, a query can contain query ID delimited by a
colon:
Q1:one two three
~~ ~~~~~~~~~~~~~
query ID terms
For example:
$ ./bin/queries \
-e opt # index encoding
-a and # retrieval algorithm
-i test_collection.index.opt # index path
-w test_collection.wand # metadata file
-q ../test/test_data/queries # query input file
This performs conjunctive queries (and
). In place of and
other
operators can be used (see Query algorithms), and
also multiple operators separated by colon (and:or:wand
), which will
run multiple passes, one per algorithm.
If the WAND file is compressed, append --compressed-wand
flag.
Build additional data¶
To perform BM25 queries it is necessary to build an additional file containing the parameters needed to compute the score, such as the document lengths. The file can be built with the following command:
$ ./bin/create_wand_data \
-c ../test/test_data/test_collection \
-o test_collection.wand
If you want to compress the file append --compress
at the end of the
command. When using variable-sized blocks (for VBMW) via the
--variable-block
parameter, you can also specify lambda with the `-l
or
–lambda flags. The value of lambda impacts the
mean size of the variable blocks that are output. See the VBMW paper
(listed below) for more details. If using fixed-sized blocks, which is
the default, you can supply the desired block size using the
-b or
–block-size
Query algorithms¶
Here is the list of the supported query processing algorithms.
AND¶
Unranked (and
) or ranked (ranked_and
) conjunction.
OR¶
Unranked (or
) or ranked (ranked_or
) union.
MaxScore¶
Howard Turtle and James Flood. 1995. Query evaluation: strategies and optimizations. Inf. Process. Manage. 31, 6 (November 1995), 831-850. DOI=http://dx.doi.org/10.1016/0306-4573(95)00020-H
WAND¶
Andrei Z. Broder, David Carmel, Michael Herscovici, Aya Soffer, and Jason Zien. 2003. Efficient query evaluation using a two-level retrieval process. In Proceedings of the twelfth international conference on Information and knowledge management (CIKM ‘03). ACM, New York, NY, USA, 426-434. DOI: https://doi.org/10.1145/956863.956944
BlockMax WAND¶
Shuai Ding and Torsten Suel. 2011. Faster top-k document retrieval using block-max indexes. In Proceedings of the 34th international ACM SIGIR conference on Research and development in Information Retrieval (SIGIR ‘11). ACM, New York, NY, USA, 993-1002. DOI=http://dx.doi.org/10.1145/2009916.2010048
BlockMax MaxScore¶
Variable BlockMax WAND¶
Antonio Mallia, Giuseppe Ottaviano, Elia Porciani, Nicola Tonellotto, and Rossano Venturini. 2017. Faster BlockMax WAND with Variable-sized Blocks. In Proceedings of the 40th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR ‘17). ACM, New York, NY, USA, 625-634. DOI: https://doi.org/10.1145/3077136.3080780