AQL

An SQL-like interface for AntidoteDB.

Installation

AQL can be used through Docker (recommended), or directly through rebar3.

Docker

To use AQL through Docker simply pull the image from Docker Hub here. If docker can't pull the lastest version of the image, do it manually by:

    docker pull jpdsousa/aql_antidote:<latest-version-available>

This image starts an antidoteDB server (uses this image) on background and runs an AQL instance of top.

This is the recommended way of running AQL, at least for single-client use.

Rebar3

This project can also be installed "manually" through rebar3. In order to do so, clone this repository:

    $ git clone https://github.com/JPDSousa/AQL

Open a terminal in the project folder (cd AQL) and then compile the project:

    $ make compile

Now, to run the client, you must have one (or more) running instances of AntidoteDB. To start in shell mode run the following command:

    $ make shell

You can also start in development mode with:

    $ make dev

Getting started

AQL is an SQL-variant, designed to work with AntidoteDB API.

Shell

AQL provides a shell mode, which is the easiest way to use the client. In shell mode, you'll see a prompt like this:

    AQL>

Use the prompt to input AQL statements.

API

The AQL API is pretty straightforward. There is a main module called aqlparser with a method parse, which takes a tuple as well as the AntidoteDB node long name. The two options available are:

{str, AQLCommand}

Which parses the AQLCommand and outputs the result.

{file, AQLFile}

Which takes a path to a file (no specific format) and parses its content as an AQL command.

For instance, to show all existing tables in the database through the API, use:

aqlparser:parse({str, "SHOW TABLES"}, 'antidote@127.0.0.1').

AQL Docs

AQL supports multiple SQL-like operations such as:

• Data definition
  • CREATE TABLE
• Data manipulation
  • SELECT
  • INSERT
  • UPDATE
  • DELETE
• Admin
  • SHOW TABLES/INDEX

AQL supports a limited set of types:

• VARCHAR - common text data type (similar to SQL's VARCHAR)
• INTEGER/INT - common integer data type (similar to SQL's INTEGER)
• BOOLEAN - common boolean
• COUNTER_INT - integer counter, with bounds (based on AntidoteDB's Bounded Counter)

CREATE TABLE

Creates a new table. If the table already exists the new table will overwrite it (any concurrent conflicts will be resolved with a Last Writer Wins CRP).

CREATE @AW TABLE Student (
	id INT PRIMARY KEY,
	Name VARCHAR,
	Age INT DEFAULT 18,
	YearsLeft COUNTER_INT CHECK GREATER 0,
	Passport_id INTEGER FOREIGN KEY @FR REFERENCES Passport(id)
);

Primary keys

The primary key constraint must be specified after the column which is to be set as the primary key (multiple columns as primary keys are not supported). Any datatype can be a primary key.

Primary keys only guarantee uniqueness. Although, if two rows with the same primary key are inserted (either concurrently or not), both insertions will be merged, and all columns columns will also be merged according to its datatypes.

Check Constraints

AQL also supports constraints on counters (counter_int). Assign numeric bounds to any COUNTER_INT column by:

CHECK [ GREATER | GEQ | SMALLER | SEQ] value

Where value is the respective bound.

Default Values

You can also define a default value for a record (not allowed in primary keys). Default values are used when no value is specified for a record.

Syntax:

column_x data_type DEFAULT value

Where value is the default value.

Foreign Keys

Foreign keys allow users to create custom relations between elements of different tables. To create a foreign key relation simply add to the column that will be the foreign key: FOREIGN KEY [ @FR | @IR ] REFERENCES _parentTable_(_parentColumn_), where _parentTable_ is the parent table name (e.g. Passport) and _parentColumn_ is the parent column name (e.g. id). All foreign keys must point to columns with a unique constraint, which is only guaranteed in primary keys.

Force-revive (@FR) and Ignore-revive (@IR) are conflict resolution policies used to resolve any referential integrity related conflicts generated by concurrent operations. Force-revive will revive all records (deleted) involved in the conflict, while Ignore-Revive deletes all involved records in case of conflict.

SELECT

SELECT is the main read operation in AQL (similar to SQL). The operation issues a read operation in the database engine (AntidoteDB).

SELECT * FROM Persons WHERE PersonID = 20;

Note: This operation only supports reads per primary key (such as the one in the example). This is a temporary limitation.

INSERT

Inserts new records in a table. If a value with the primary key already exists it will be overwritten.

INSERT INTO (PersonID, LastName, FirstName, Address, City) VALUES (10, 'Last1', 'First1', 'Local1', 'City1')

The table columns must always be specified.

UPDATE

Updates an already-existent row on the specified table.

UPDATE Persons
SET FirstName ASSIGN 'First2'
WHERE PersonID = 1

Updates all rows in table Persons where PersonID has value 1. The update sets column FirstName to value 'First2'. The operation keyword (e.g. ASSIGN) depends on the AQL datatype:

• VARCHAR
  • ASSIGN - sets the column(s) of type VARCHAR to the value specified.
• INTEGER
  • ASSIGN - sets the column(s) of type INTEGER or INT to the value specified.
  • INCREMENT - increments the column(s) of type INTEGER by the value specified.
  • DECREMENT - decrements the column(s) of type INTEGER by the value specified.
• COUNTER_INT
  • INCREMENT - increments the column(s) of type COUNTER_INT by the value specified.
  • DECREMENT - decrements the column(s) of type COUNTER_INT by the value specified.
• BOOLEAN
  • ENABLE- sets the boolean value to true
  • DISABLE- sets the boolean value to false

Just like in a SELECT operation, the where clause can only filter primary keys.

DELETE

Deletes a set of records from the specified table.

DELETE FROM Persons Where PersonID = 2004525

Just like in a SELECT operation, the where clause can only filter primary keys. If the WHEREclause is absent, all the records in the table are deleted.