YADI was written by Marcello Benedetti, Ephrem Berhe Gebremariam, Falitokiniaina Rabearison, Kiril Sardjoski, Reddy Aldino, and Ivan Vukić. It was written as a project for the Advance databases course which is part of Data Mining and Knowledge Management european master.

YADI is Command Line Interpreter for Datalog queries. It parses and evaluates Datalog queries on top of an SQL engine. Python language is used. Parsing of Datalog queries is achieved with PLY (Python Lex-Yacc). PostgreSQL database system is used.

YADI transforms a Datalog query to an Abstract Syntax Tree and provides with a query evaluation mechanism. YADI convert the query to an SQL statement and delegate the evaluation to the backend SQL engine, moreower additional evaluation algorithms were designed.

The following Datalog features have been implemented:

• selection
• conjunctive queries
• anonymous variables
• cross product
• constraints
• union
• negation

Available utilities:

• database connection manager
• database status and schema descriptor
• Datalog scripting

The programming language is Python 3. It is available for any Win32/Linux/MacOSX box. A local or remote PostgreSQL database is also needed.

Dependecies In order to run this software, it is necessary to have the following libraries installed in the machine:

• ply (Python Lex-Yacc)
• psycopg2 (PostgreSQL connection driver)
• sqlalchemy (SQL toolkit) The last version of these libraries can be easily intalled using pip (Python Package Index).

Pre-requisites For running YADI it is necessary to have a connection to PostgreSQL database. When starting the program it would be necessary to provide a username, database name, host, port and password. The user will need having write/read permission over the database.

python gui.py

Connection to the database can be done from the user interface. Default connection string: postgresql+psycopg2://postgres:root@localhost:5432/adb

A Datalog rule for the database { movie(Title,Director), actor(Name,Lastname,Title) } looks like this:

example(X):-actor(X,_,Y) and movie(Y,Z) and Z!=rahimi.

Such rule represents a join between actor and movie on the "Title" column and filters out movies where the director is "rahimi". The Datalog query for the new rule is:

example(X).	

Please feel free to send us feedback about forks, patches and any other kind. You can contact us via GitHub and also via email.

Ivan Vukic: vukicivan@yahoo.com

Ephrem Berhe Gebremariam: eepphhrreemm@gmail.com

Marcello Benedetti: 4marcello@gmail.com

Falitokiniaina Rabearison: r.falitokiniaina@gmail.com

Kiril Sardjoski: kiril.sardjoski@gmail.com

Reddy Aldino: redino26@gmail.com

Copyright (c) 2013. Authors.

This code is distributed freely with no charges. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without limitation of the rights to use, copy, modify, merge or distribute this software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.