SlamEngine

The NoSQL analytics engine that powers SlamData.

This is the open source site for SlamData for people who want to hack on or contribute to the development of SlamData.

For pre-built installers for the SlamData application, please visit the official SlamData website.

Building from Source

Note: This requires Java 7. SlamData only supports MongoDB 2.6.X

Checkout

git clone git@github.com:slamdata/slamengine.git

Build

./sbt one-jar

The build process will ask

Multiple main classes detected, select one to run:

 [1] slamdata.engine.repl.Repl
 [2] slamdata.engine.api.Server

Choose 1 for a jar that offers a standalone interactive session, or 2 for a server that the SlamData front-end (or any HTTP client) can talk to.

The path of the JAR will be ./target/scala-2.10/slamengine_2.10-[version]-SNAPSHOT-one-jar.jar, where [version] is the SlamEngine version number.

Configure

Create a configuration file with the following format:

{
  "server": {
    "port": 8080
  },

  "mountings": {
    "/": {
      "mongodb": {
        "database":       "foo",
        "connectionUri":  "mongodb://..."
      }
    }
  }
}

Run

java -jar path/to/slamengine.jar [config file]

REPL Usage

The interactive REPL accepts SQL SELECT queries.

slamdata$ select * from zips where state='CO' limit 3
...
{ "_id" : "80002" , "city" : "ARVADA" , "loc" : [ -105.098402 , 39.794533] , "pop" : 12065 , "state" : "CO"}
{ "_id" : "80003" , "city" : "ARVADA" , "loc" : [ -105.065549 , 39.828572] , "pop" : 32980 , "state" : "CO"}
{ "_id" : "80004" , "city" : "ARVADA" , "loc" : [ -105.11771 , 39.814066] , "pop" : 33260 , "state" : "CO"}

slamdata$ select city from zips limit 3
...
{ "_id" : "35004" , "city" : "ACMAR"}
{ "_id" : "35005" , "city" : "ADAMSVILLE"}
{ "_id" : "35006" , "city" : "ADGER"}

API Usage

The server launches a simple JSON API.

POST /query/fs/[path]?foo=var

Executes a SQL query, contained in the request body, on the backend responsible for the request path.

The Destination header must specify the output path, where the results of the query will become available if this API successfully completes.

All paths referenced in the query, as well as the output path, are interpreted as relative to the request path, unless they begin with /.

SlamSQL supports variables inside queries (SELECT * WHERE pop > :cutoff). Values for these variables should be specified as query parameters in this API. Failure to specify valid values for all variables used inside a query will result in an error.

This API method returns the name where the results are stored, as an absolute path, as well as logging information.

{
  "out": "/[path]/tmp231",
  "phases": [
    ...
  ]
}

If an error occurs while compiling or executing the query, a 500 response is produced, with this content:

{
  "error": "[very large error text]",
  "phases": [
    ...
  ]
}

The phases array contains a sequence of objects containing the result from each phase of the query compilation process. A phase may result in a tree of objects with type, label and (optional) children:

{
  ...,
  "phases": [
    ...,
    {
      "name": "Logical Plan",
      "tree": {
        "type": "LogicalPlan/Let",
        "label": "'tmp0",
        "children": [
          {
            "type": "LogicalPlan/Read",
            "label": "./zips"
          },
          ...
        ]
      }
    },
    ...
  ]
}

Or a blob of text:

{
  ...,
  "phases": [
    ...,
    {
      "name": "Mongo",
      "detail": "db.zips.aggregate([\n  { \"$sort\" : { \"pop\" : 1}}\n])\n"
    }
  ]
}

Or an error (typically no further phases appear, and the error repeats the error at the root of the response):

{
  ...,
  "phases": [
    ...,
    {
      "name": "Physical Plan",
      "error": "Cannot compile ..."
    }
  ]
}

GET /metadata/fs/[path]

Retrieves metadata about the files, directories, and mounts at the specified path.

{
  "children": [
    {"name": "test", "type": "mount"},
    {"name": "foo", "type": "directory"},
    {"name": "bar", "type": "file"}
  ]
}

GET /data/fs/[path]?offset=[offset]&limit=[limit]

Retrieves data from the specified path, formatted as one JSON object per line. The offset and limit parameters are optional, and may be used to page through results.

{"id":0,"guid":"03929dcb-80f6-44f3-a64c-09fc1d810c61","isActive":true,"balance":"$3,244.51","picture":"http://placehold.it/32x32","age":38,"eyeColor":"green","latitude":87.709281,"longitude":-20.549375}
{"id":1,"guid":"09639710-7f99-4fe1-a890-b1b592cbe223","isActive":false,"balance":"$1,544.65","picture":"http://placehold.it/32x32","age":27,"eyeColor":"blue","latitude":52.394181,"longitude":-0.631589}
{"id":2,"guid":"e71b7f01-ce0e-4824-ad1e-4e118872aec4","isActive":true,"balance":"$1,882.92","picture":"http://placehold.it/32x32","age":24,"eyeColor":"green","latitude":30.061766,"longitude":-106.813523}
{"id":3,"guid":"79602676-6f63-41d0-9c0a-a4f5851a43db","isActive":false,"balance":"$1,281.00","picture":"http://placehold.it/32x32","age":25,"eyeColor":"blue","latitude":14.713939,"longitude":62.253264}
{"id":4,"guid":"0024a8ad-373f-459a-8316-d50d7a8f7b10","isActive":true,"balance":"$1,908.50","picture":"http://placehold.it/32x32","age":26,"eyeColor":"brown","latitude":-21.874648,"longitude":67.270659}
{"id":5,"guid":"f7e33b92-a885-450e-8ad5-92103b1f5ff3","isActive":true,"balance":"$2,231.90","picture":"http://placehold.it/32x32","age":31,"eyeColor":"blue","latitude":58.461107,"longitude":176.40584}
{"id":6,"guid":"a2863ec1-9652-46d3-aa12-aa92308de055","isActive":false,"balance":"$1,621.67","picture":"http://placehold.it/32x32","age":34,"eyeColor":"blue","latitude":-83.908456,"longitude":67.190633}

PUT /data/fs/[path]

Replaces data at the specified path, formatted as one JSON object per line in the same format as above. Either succeeds, replacing any previous contents atomically, or else fails leaving the previous contents unchanged.

POST /data/fs/[path]

Appends data to the specified path, formatted as one JSON object per line in the same format as above. If an error occurs, some data may have been written, and the content of the response describes what was done.

DELETE /data/fs/[path]

Removes all data at the specified path. Single files are deleted atomically.

MOVE /data/fs/[path]

Moves data from one path to another within the same backend. The new path must be provided in the "Destination" request header. Single files are deleted atomically.

Troubleshooting

First, make sure that the slamdata/slamengine Github repo is building correctly (the status is displayed at the top of the README). Then, you can use

./sbt test

to ensure that your local version is also passing the tests.

Check to see if the problem you are having is mentioned in the Github issues and, if it isn’t, feel free to create a new issue.

You can also discuss issues on the SlamData IRC channel: #slamdata on Freenode.

Legal

Released under the GNU AFFERO GENERAL PUBLIC LICENSE. See LICENSE file in the repository.

finid/slamengine