CouchDB FDW (beta) for PostgreSQL 9.1+
======================================
This PostgreSQL extension implements a Foreign Data Wrapper (FDW) for
the CouchDB document-oriented database: http://couchdb.apache.org/
IMPORTANT: There're bugs in the existing version. I'm working on it and will
be releasing another version very soon.
Building
--------
To build the code, you need the yajl(Yet Another JSON Library) and libcurl installed
on your system.
You can checkout the yajl from GitHub:
https://github.com/lloyd/yajl
OR
download from:
http://lloyd.github.com/yajl/
libcurl C interface can be found here:
http://curl.haxx.se/libcurl/c/
Once that's done, the extension can be built with:
PATH=/usr/local/pgsql91/bin/:$PATH make USE_PGXS=1 make
sudo PATH=/usr/local/pgsql91/bin/:$PATH make USE_PGXS=1 install
(assuming you have PostgreSQL 9.1 in /usr/local/pgsql91).
I've tested on Mac OS X 10.6 only, but other *nix's should also work.
I haven't tested on Windows, but the code should be good on MinGW.
Limitations
-----------
- If there is no quals to pushdown, we get a list of '_id's to begin with,
and then fetch whatever records still exist as we build the tuples.
- We can only pushdown '_id' (with or without '_rev') to CouchDB, which must use
the TEXTEQ operator.
- The top-level-attributes of a document can be mapped to columns in a
foreign table.
- In case you want the map a column to the entire JOSN doc, use
columnname '_doc'
in foreign table options (which means your remote couchdb shouldn't have
a top-level-attribute called '_doc', otherwise there will be conficts).
Usage
-----
The following parameters can be set on a CouchDB foreign server:
address: The address or hostname of the CouchDB server.
Default: 127.0.0.1
port: The port number on which the CouchDB server is listening.
Default: 5984
The following parameter can be set on a CouchDB foreign table:
database: The numeric ID of the CouchDB database to query.
Default: test
<column name>: The column mapping to remote JSON attributes.
If there is no column mapping specified, default is the origninal column name.
Please note that '_doc' is reserved for mapping the entire JSON document.
The following parameter can be set on a user mapping for a CouchDB
foreign server:
username: The username to authenticate to the CouchDB server with.
Default: <none>
password: The password to authenticate to the CouchDB server with.
Default: <none>
Example
-------
CREATE SERVER couchdb_server
FOREIGN DATA WRAPPER couchdb_fdw
OPTIONS (address '127.0.0.1', port '5984');
CREATE FOREIGN TABLE couchdb_table (key text, value text)
SERVER couchdb_server
OPTIONS (database 'testdb', key '_id', value '_doc');
CREATE USER MAPPING FOR PUBLIC
SERVER couchdb_server
OPTIONS (username 'testuser', password 'secret');
--
Zheng Yang
zhengyang4k@gmail.com
