qlever 0.3.8

Script for using the QLever SPARQL engine.

QLever Control

This is a small repository, which provides a script qlever that can control everything that QLever does. The script is supposed to be very easy to use and pretty much self-explanatory as you use it. If you use Docker, you don't even have to download any QLever code (Docker will pull the required images) and the script is all you need.

Installation

Simply do pip install qlever and make sure that the directory where pip installs the package is in your PATH. Typically, pip will warn you when that is not the case and tell you what to do.

Usage

First, create an empty directory, with a name corresponding to the dataset you want to work with. For the following example, take olympics. Go to that directory, and do the following:

qlever                         # Basic help + lists of available pre-configs
qlever setup-config olympics   # Get examplary Qleverfile (config file)
qlever get-data                # Download the dataset (see below)
qlever index                   # Build index data structures for this dataset
qlever start                   # Start a QLever server using that index
qlever test-query              # Launch a test query 
qlever ui                      # Launch the QLever UI

This will create a SPARQL endpoint for the 120 Years of Olympics dataset. It is a great dataset for getting started because it is small, but not trivial (around 2 million triples), and the downloading and indexing should only take a few seconds.

Each command will also show you the command line it uses. That way you can learn, on the side, how QLever works internally. If you just want to know the command line for a particular command, without executing it, you can append "show" like this:

qlever index show

There are many more commands and options, see qlever --help. The script supports autocompletion for all its commands and options. You can (and should) activate it following the instructions given when you just type qlever without any arguments.

For developers

The (Python) code for the script is in the *.py files in src/qlever. The preconfigured Qleverfiles are in src/qlever/Qleverfiles.

If you want to make changes to the script, git clone this repository, make any changes you want, and run pip install -e .. Then you can use the script (with whatever modifications you have made), just as if you had installed it via pip install qlever. Note that unless you change the directory structure, you have to execute pip install -e . only once (this local installation will not copy your files but link to them).