create extension hstore;
Key/value inside db column, keys and values are string-only
k => v
foo => bar, baz => whatever
"1-a" => "anything at all"
In database behaves like a dictionary, ability to do basic dictionary a set operations
GiST and GIN indexes for @>, ?, ?& a ?| operators; hash and btree for = - support for UNIQUE, GROUP BY, ORDER BY a DISTINCT
In psycopg2 from version 2.3, enabling through
psycopg2.extras.register_hstore(conn_or_curs, globally=False, unicode=False, oid=None, array_oid=None)
hstore is converted from/to dictionary (allowing only string/unicode keys and values)
pip install django-hstore
In Django you can use it after installing extension as normal dictionary in your model
from django.db import models
from django_hstore import hstore
class Product(models.Model):
name = models.CharField(max_length=250)
data = hstore.DictionaryField(db_index=True)
objects = hstore.Manager()
SQLAlchemy supports hstore from version 0.8 as postgresql.HSTORE type and postgresql.hstore() function
In SQLAlchemy ORM the best practice is to combine it with MutableDict (then it behaves like in Django)
data = Column(MutableDict.as_mutable(HSTORE))