Mql to-sql - a json-based rdbms query language

MQL-to-SQL a JSON-based query language for RDBMS data access from AJAX applications

Welcome!
Roland Bouman, Leiden, the Netherlands
Ex-MySQL, ex-Sun Microsystems
Web & BI developer at Strukton Rail
Author
“Pentaho Solutions”
“Pentaho Kettle Solutions”
http://rpbouman.blogspot.com , @rolandbouman

Agenda
The data access problem
What's wrong with SQL?
The Metaweb Query Language (MQL)
MQL-to-SQL
Demo
Questions

The Data Access Problem
Web application
Classical Client/Server
SQL Resultset SQL Resultset RDBMS HTTP Browser Desktop Application ?

Build a service
Protocol on top of HTTP: REST, RPC
Data format: JSON, XML
Advantage: controlled data access
Disadvantage: controlled=limited

Advantage: unlimited data access
Disadvantage: unlimited=uncontrolled
SQL SQL Resultset JSON
Build a query service
Example: dbslayer

Agenda
MQL-to-SQL
Demo
Questions

Nothing of course, it's great!!!
very powerful
expressive syntax
declarative
designed for the RDBMS
portable
well supported

SQL is very powerful
...way too powerful
SQL has expressive syntax
...and too hard to parse and generate
SQL is declarative
...but not enough
SQL is designed for the RDBMS
...can't escape relational model

SELECT f.title , f.description , f.release_year , f.length , f.rating , a.first_name , a.last_name , l.name FROM film f INNER JOIN language l ON f.language_id = l.id LEFT JOIN film_actor fa ON f.id = fa.film_id LEFT JOIN actor a ON fa.actor_id = a.id SQL not declarative enough Spoken in Has cast Starring in

SELECT f.title , f.description , f.release_year , f.length , f.rating , a.first_name , a.last_name , spoken_in.name FROM film f RELATE spoken_in language l , has_cast film_actor fa RELATE starring_in actor a SQL not declarative enough Spoken in Has cast Starring in

SQL can't escape the RM Unnormalized data Split off – multivalued attributes – repeating groups First normal form (1NF) Higher normal forms (>= 3NF) Remove redundancy Denormalized data (1NF) SQL queries: – JOIN operation ??? Header – line 1a – line 2b header line 1a line 2b header 1 2 line 1a line 2b header line 1a header line 2b

SQL can't escape the RM

SELECT f.* , l.*, ol.* , (SELECT * FROM film_category fc INNER JOIN category c ON fc.category_id = c.id WHERE fc.film_id = f.film_id) , (SELECT * FROM film_actor fa INNER JOIN actor a ON fa.actor_id = a.id WHERE fa.film_id = f.film_id) FROM film f INNER JOIN language l ON f.language_id = l.id INNER JOIN language ol ON f.original_language_id = ol.id SQL can't escape the RM

SELECT f.* , l.*, ol.* , c.*, a.* FROM film f INNER JOIN language l ON f.language_id = l.id INNER JOIN language ol ON f.original_language_id = ol.id LEFT JOIN film_category fc ON f.id = fc.film_id LEFT JOIN category c ON fc.category_id = c.id LEFT JOIN film_actor fa ON f.id = fa.film_id LEFT JOIN actor a ON fa.actor_id = a.id SQL can't escape the RM

How do we get rid of SQL?
Object relational mapper?
NoSQL?
Document databases
ACID
Schema flexibility
Can we preserve the RM?

Agenda
MQL-to-SQL
Demo
Questions

The Metaweb Query Language
MQL – rhymes with “pickle”
Native query language of Freebase
http://www.freebase.com/
http://www.freebase.com/docs
JSON over HTTP
Natural fit for AJAX applications

Freebase MQL Services
http://api.freebase.com/api/service/mqlread? query ={"query":[{ Your MQL here }]}
http://api.freebase.com/api/service/mqlread? queries ={"q1": {"query":[{ Your MQL here }]}, "q2": {"query":[{ Your MQL here }]}}
http://api.freebase.com/api/service/mqlwrite

JSON
Subset of JavaScript
Object : set of property/value pairs
Scalar: boolean, null, number, string
Array: list of values
{ "type" : "/sakila/film" , "film_id" : 1 , "title" : "ACADAMY DINOSAUR" , "language" : { "language_id" : 1 , "language_name" : "English" } , "category" :[ "Action" , "Adventure" ] }

JSON is great for AJAX
Modern Web applications
Asynchronous JavaScript and XML
...except it's JSON rather than XML
1 to 1 runtime representation
XML requires mapping, DOM traversal
JSON support in all modern browsers
Cross-domain requests (JSONP)
<script> injection

MQL Queries
JSON-based
Both Query and Result
MQL is “query by example”
MQL Query is an object template
Finds objects matching the template
Fills in value placeholders in template
Query & Result symmetry
Easy to parse, easy to generate

Basic MQL query { "type" : "/sakila/film" , "film_id" : 1 , "title" : "ACADAMY DINOSAUR" , "language" : { "language_id" : 1 , "language_name" : "English" }, "category": [ "Action" , "Adventure" ] } { "type" : "/sakila/film" , "film_id" : 1 , "title" : null , "language" : { "language_id" : null , "name" : null }, "category" : [] } Query: Result:
Property/value pairs act as filter
Value placeholders return data

Meta: Objects & Properties
Objects are bags of properties
Properties
name/value pairs
Single- or multi-valued (array)
Value can be scalar or object
No explicit relationships
Implicit: properties with object values

Meta: Types
Types define a bag of properties
Objects may have multiple types
Types are grouped in domains
In MQL, use the type property
type : "/domainname/typename"
Property has exactly 1 expected type

MQL Joins/subqueries
Implicit via object-type properties
Can't specify join conditions

MQL operators
Property/value act as equals operator
Explicit operators for advanced filters
!= , < , <= , >= , >
Have their usual meaning
|= and !|= test for membership
"one of" and "not one of"
~= for word pattern matching

MQL operators { "type" : "/sakila/film" , "film_id": 1 } { "type" : "/sakila/film" , "film_id < " : 2 , "title ~= " : "ACADEMY" , "language != " : "Danish" , "category |= " : [ "Action", "Adventure" ], "film_id" : null } Query: Result:
Operators follow the property name
Operations not returned in the result

MQL property aliases { "type" : "/sakila/film" , "film_id" : null , "title" : null , "1:category" : "Action", "2:category" : "Adventure" } Query:
Implement an AND operation

MQL directives
Reserved property names
limit
return: count
cursor
* wildcard

Agenda
MQL-to-SQ L
Demo
Questions

MQL-to-SQL
Implementation of mqlread service
PHP using PDO database access
MySQL, PostgreSQL, SQLite, Oracle
http://code.google.com/p/mql-to-sql
GPL
Lacks many features, has many bugs
don't use in hospitals and airplanes

MQL-to-SQL
MQL domain maps to a SQL schema
MQL type maps to a SQL table
MQL property maps to
SQL column
Relationship (foreign key)
Mappings defined in JSON file

MQL-to-SQL index.php config.php <?php include 'config.php' ; ...code... ?> <?php $connection_file_name = ''; $metadata_file_name = ''; ?>

MQL-to-SQL metadata file { "domains" : { "sakila" : { "schema_name" : "" , "types" : { "actor" : { "properties" : { "actor_id" : { "column_name" : "actor_id" , "nullable" : false , "type" : "/type/int" }, "starring_in" : { "type" : "/sakila/film_actor" , "direction" : "referenced<-referencing" , "join_condition" : [ { "referencing_column" : "actor_id" , "referenced_column" : "actor_id" },

Agenda
MQL-to-SQL
Demo
Questions

Finally
I need your feedback
Love to see this inside a RDBMS
drizzle plugin?
MySQL plugin?
PostgreSQL SP language?
http://code.google.com/p/mql-to-sql/
Online query editor

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Mql to-sql - a json-based rdbms query language

by rpbouman on Apr 13, 2011

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