CompleteSearch

Old Wiki from the MPII (lots of detailed / internal information)

Quick Intro

Follow these steps to checkout the CompleteSearch code from our SVN, build it, build an index, run a server on that index, and ask queries to that server via HTTP. Don't be afraid, it's easy. If you have questions, send an email to Hannah Bast <bast@informatik.uni-freiburg.de>.

0. Get source code

svn checkout
http://ad-svn.informatik.uni-freiburg.de/completesearch/codebase
Username: [ask us]
Password: [ask us]

1. Compile

make all

This will build three binaries:

• buildIndex
• buildDocsDB
• startCompletionServer

If you call any of these binaries without parameters you will get usage info with all the available options.

2. Input (to be produced by a suitable parser)

Ínput 1: a file <base-name>.words, with lines of the form

<word><TAB><doc id><TAB><score><TAB><position>

This file must be sorted such that sort -c -k1,1 -k2,2n -k4,4n does not complain.

Input 2: a file <base-name>.docs, with lines of the form

<doc id><TAB>u:<url of document><TAB>t:<title of document><TAB>H:<raw text of document>

This file must be sorted so that sort -c -k1,1n does not complain.

You find a very simple example under http://www.mpi-inf.mpg.de/~bast/topsecret/example.tgz

3. Build the word index

buildIndex HYB <base-name>.words

This produces the (binary) index file <base-name>.hybrid. It enables fast processing of the powerful query language offered by CompleteSearch (including full-text search, prefix search and completion, synonym search, error-tolerant search, etc.).

buildIndex also produces the file <base-name>.vocabulary that provides the mapping from word ids to words. This is an ASCII file, you can just look at it.

Note that by default, the HYB index is built with block of fixed sizes. It is more efficient though to pass it an explicit list of block boundaries (-B option). TODO: say something about this here, it's actually quite easy.

4. Build the doc index

buildDocsDB <name>.docs

This produces the (binar) file <base-name>.docs.DB which provides an efficient mapping from doc ids to documents. This is needed if you want to show excerpts / snippets from documents matching the query (which is almost always the case).

5. Start server

startCompletionServer -Z <base-name>.hybrid

This starts the server. If you run it without argument, it prints usage information and shows you the (very many) command line options. The -Z argument lets the server run in the foreground, and output everything to the console, which is convenient for testing. The default mode is to run as a background process and write all output to a log file.

6. Queries

The server listens on the port you specified in step 6 (8888 by default), and speaks HTTP. For example:

curl "http://localhost:8888/?q=die*&h=1&c=3"

This will return the result as an XML, which should be self-explanatory.

Here is the list of parameters which you may pass along with the query (q=...)

• h : number of hits
• c : number of completions (of last query word, if you put a * behind it)
• f : send hits starting from this one (default: 0)
• en : number of excerpts per hit
• er : size of excerpt
• rd : how to rank the documents (0 = by score, 1 = by doc id, 2 = by word id, append a or d for ascending or descending)
• rw : how to rank the words (0 = by score, 1 = by doc count, 2 = by occurrence count, 3 = by word id, 4 = by doc id, append a or d as above)
• s : how to aggregate scores (expert option, ignore for the moment)
• format : one of xml, json, jsonp. Return result in that format.