Redland RDF Library Manual |
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This module is based on the MySQL store and is compiled in when PostgreSQL is available. This store provides storage using the PostgreSQL open source database including contexts. This store was added in Redland 1.0.3.
There are several options required with the postgresql storage in order to connect to the database. These are:
host
for the database server hostname
port
for the database server port (defaults to the Postgresql port 3306 if not given)
database
for the Postgresql database name (not the storage name)
user
for the database server user name
password
for the database server password
database
for the Postgresql database name (not the storage name)
NOTE: Before Redland 1.0.5, the
parameter dbname
had to be used instead
of database
for the Postgresql database name.
NOTE: Take care exposing the password as for example, program
arguments or environment variables. The rdfproc utility can with
help this by reading the password from standard input. Inside
programs, one way to prevent storing the password in a string is to
construct a Redland hash of the storage options such as
via librdf_hash_from_string
and use
librdf_new_storage_with_options
to create a storage.
The rdfproc utility source code demonstrates this.
The storage name parameter given to the storage constructor
librdf_new_storage
is used inside the postgresql
store to allow multiple stores inside one PostgreSQL database
instance as parameterised with the above optiosn.
If boolean option new
is given, any existing
PostgreSQL database named by the storage
option database
, say
db will be dropped and the appropriate new
tables created. The PostgreSQL database db must
already exist, such as made with the PostgreSQL create
database
db command and the
appropriate privileges set so that the user and password
work.
This store always provides contexts; the boolean storage option
contexts
is not checked.
Examples:
/* A new PostgreSQL store */ storage=librdf_new_storage(world, "postgresql", "db1", "new='yes',host='localhost',database='red',user='foo','password='bar'"); /* A different, existing PostgreSQL store db2 in the same database as above */ storage=librdf_new_storage(world, "postgresql", "db2", "host='localhost',database='red',user='foo','password='bar'"); /* An existing PostgreSQL store on a different database server */ storage=librdf_new_storage(world, "postgresql", "db3", "host='db.example.org',database='abc',user='baz','password='blah'"); /* Opening with an options hash */ options=librdf_new_hash(world, NULL); librdf_hash_from_string(options, "host='db.example.org',database='abc',user='baz'"); librdf_hash_put_strings(options, "password", user_password); storage=librdf_new_storage_with_options(world, "postgresql", "db4", options);
In PHP:
# An existing store $storage=librdf_new_storage($world, 'postgresql', 'db4', "host='127.0.0.1',database='xyz',user='foo',password='blah'");
Summary:
Persistent
Suitable for very large models
Indexed but not optimized
Smaller disk usage than BDB
Contexts always provided