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I am very new to mathematica but it looks like an interesting language and I would like to explore it for a future project to create a web search engine. It seems like it would be fairly well suited for this as it seems to already be powering wolfram alpha.

I was wondering if the only databases you can hook into are SQL like databases. I can't see anywhere that talks about hooking into Mongo or a graph database like Neo4j. Why is this? Does this not make sense for some reason?

Any thoughts would be great. Thanks.

Edit:

So ya. If you have examples of ways to connect Mathematica to MongoDB that would be awesome. If possible I would also like to see an example of connecting it to Neo4j. (Or reasons why that would not make sense). I guess I am wondering why everything for Mathematica is being used to connect to SQL databases thus far? Is there a reason for that?

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You can connect MongoDB to Mathematica but it is not as straight forward as using the built in SQL connectors. A possible advantage of Mongo, and possibly Couch and similar, is that in theory you should be able to access these from a free CDF. –  Mike Honeychurch Jan 19 at 22:17
4  
If you re-word your question I'll dig up some MongoDB set up instructions and code and post later today. –  Mike Honeychurch Jan 19 at 22:28
    
Cool. Thanks. I updated it. Why are NoSQL databases less popular with Mathematica? And what about using a graph database like neo4j. The one way I was thinking of going about this could be using Clojuratica (call mathematica from clojure), and use clojure to access the database. –  user2433617 Jan 21 at 2:44

2 Answers 2

up vote 12 down vote accepted

Here are the two ways I have successfully used MongoDB with Mathematica. AFAIK much of this would also apply to similar DBs such as CouchDB.

A. Easy way

One working example used a third party Mongo supplier such as 28msec.io and use URLFetch e.g.

enter image description here

With this supplier you can both read from and write to the database using HTTP GET and simple query strings. While I have not tested it, it seems to me that you should be able to make calls to a set up such as this from a free CDF (it is my understanding that you can import from a URL from free CDF).

B. Stand alone implementation

I have installed MongoDB on my Mac and got it working with Mathematica using this method:

enter image description here

I do not imagine that the set up would be too different on other systems. To interface with Mathematica I have used the REST API. For me as a non-Java programmer this was far more straight forward than trying to make a JLink connector. I have no idea of performance issues of the REST API vs purpose built JLink connector. For the intended application there were no noticeable problems, slowdowns etc.

1 Download and install MongoDB.

2 Start the webserver

$ sudo apachectl start

3 Start Mongo DB

$ mongod --rest

4 Check that everything is working on port 28017

127.0.0.1:28017

enter image description here

The problem with the install is that the bundled REST interface does not allow inserting etc. Full REST capabilities can be achieved with an external tool such as sleepy mongoose.

5 Install pymongo

$ easy_install pymongo

6 Download and install sleepy.mongoose.

You are now in business and can read from and write to your local MongoDB from Mathematica using URLFetch.

enter image description here

Edit

Forgot to mention that you use ImportString[ string, "JSON"] to convert the JSON to rules. Also forgot to mention that for easy option A, or similar database providers, if you can enter the login and password as part of the query string then you can use Import to read from, and write to, the database.

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Wow this is awesome. Thanks! –  user2433617 Jan 21 at 21:32

Mathematica can also connect to Neo4J via the REST API. Instructions for use on OS X:

1. Install Neo4j

2. start the webserver

$ sudo apachectl start

3. start Neo4j (installation in usr/local/bin)

$ neo4j start

4. Make sure all is working

127.0.0.1:7474

enter image description here

Examples:

URLFetch["http://localhost:7474/db/data/node",
 {"StatusCode", "Content"},
 "Method" -> "POST"]

Neo4J has a cypher query language that can be used from Mathematica in an analogous way to how we use SQL queries from SQLExecute:

enter image description here

tmp = URLFetch["http://localhost:7474/db/data/cypher",
  {"StatusCode", "Content"},
  "Method" -> "POST",
  "Parameters" -> {"query" -> 
     "MATCH (a)-[r]->(b)RETURN DISTINCT head(labels(a)) AS This, type(r) AS To,   
head(labels(b)) AS That LIMIT 100"}
]

(*

{200, "{
   \"columns\" : [ \"This\", \"To\", \"That\" ],
   \"data\" : [ [ \"BusinessLine\", \"LOCATED_IN\", \"Building\" ], [ \
\"BusinessProcess\", \"CONTAINS\", \"Process\" ], [ \"BusinessProcess\
\", \"BUSINESSPROCESS_HAS_RTO\", \"RTO\" ], [ \"Process\", \
\"USED_BY\", \"BusinessLine\" ], [ \"Process\", \"PROCESS_HAS_RTO\", \
\"RTO\" ], [ \"Process\", \"USES\", \"Application\" ], [ \"RTO\", \
\"PRECEDES\", \"RTO\" ] ]
 }"}

*)

The output is JSON so

tmp2 = ImportString[tmp[[2]], "JSON"];
TableForm["data" /. tmp2]

enter image description here

Things get a bit tricky for more complex queries that return graphs but above gives the structure for connecting and querying.

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