JEQL Query Language
The JEQL Query Language is a language
which supports processing tabular data structures.
The 'E' in JEQL stands for:
- Extended - JEQL provides extensions to SQL to make it more powerful for processing data
- Efficient - JEQL's implementation makes development and execution faster!
- Embeddable - In addition to being a standalone engine, JEQL can be embedded in other applications
- ETL - Extract/Transform/Load is a major use case for JEQL
Features
- JEQL supports tables as first-class data structures
- Tables are processed using query statements expressed
using a version of SQL.
- The version of SQL used in JEQL is extended to make it easier
to perform common processing operations.
Some extensions are taken from other SQL dialects.
Others are unique to JEQL
(such as table-valued constants, table-valued functions,
and a WITH clause to allow intermediate expressions in select column lists).
- SQL queries are simply expressions in the JEQL language.
This makes it easy to chain multiple queries to accomplish a processing task.
- Tables in JEQL are loaded and queried with stream semantics,
which allows datasets larger than main memory to be processed.
- JEQL supports all usual scalar datatypes (ints, Strings, doubles).
- JEQL also provides
JTS Geometry as a built-in type,
along with a wide set of spatial functions, predicates constructors,
and aggregate functions.
This makes JEQL an excellent tool for processing spatial datasets.
- JEQL can read and write tabular data from a variety of file formats,
including text, CSV, DBF and ESRI shapefiles. It is
easy to add I/O commands for new file formats.
- JEQL is easily extensible with new functions and commands provided as Java classes.
- JEQL is supplied with a standalone script interpreter.
It is also designed to be easily embeddable in other applications
to provide scripting and data manipulation capability
- The JEQL interpreter is written in 100% pure JavaTM
Examples
See examples of JEQL functionality.
Software
The latest JEQL version is
here.
Support
The JEQL Users Mailing List is a forum to discuss all aspects of JEQL.
Documentation
Note: Documentation is under ongoing development.
License
JEQL is released under the GPL license.
JavaTM is a trademark of Sun
Microsystems, Inc. in the United States and other countries.