Incompatible changes in ArangoDB 2.6

It is recommended to check the following list of incompatible changes before upgrading to ArangoDB 2.6, and adjust any client programs if necessary.

Requirements

ArangoDB's built-in web interface now uses cookies for session management. Session information ids are stored in cookies, so clients using the web interface must accept cookies in order to log in and use it.

Foxx changes

Foxx Queues

Foxx Queue job type definitions were previously based on functions and had to be registered before use. Due to changes in 2.5 this resulted in problems when restarting the server or defining job types incorrectly.

Function-based job types have been deprecated in 2.6 and will be removed entirely in 2.7.

In order to convert existing function-based job types to the new script-based job types, create custom scripts in your Foxx app and reference them by their name and the mount point of the app they are defined in. Official job types from the Foxx app store can be upgraded by upgrading from the 1.x version to the 2.x version of the same app.

In order to upgrade queued jobs to the new job types, you need to update the type property of the affected jobs in the database's _jobs system collection. In order to see the collection in the web interface you need to enable the collection type "System" in the collection list options.

Example:

Before: "type": "mailer.postmark"

After: "type": {"name": "mailer", "mount": "/my-postmark-mailer"}

Foxx Sessions

The options jwt and type of the controller method controller.activateSessions have been deprecated in 2.6 and will be removed entirely in 2.7.

If you want to use pure JWT sessions, you can use the sessions-jwt Foxx app from the Foxx app store.

If you want to use your own JWT-based sessions, you can use the JWT functions in the crypto module directly.

Instead of using the type option you can just use the cookie and header options on their own, which both now accept the value true to enable them with their default configurations.

The option sessionStorageApp has been renamed to sessionStorage and now also accepts session storages directly. The old option sessionStorageApp will be removed entirely in 2.7.

Libraries

The bundled version of the joi library used in Foxx was upgraded to version 6.0.8. This may affect Foxx applications that depend on the library.

AQL changes

AQL LENGTH function

The return value of the AQL LENGTH function was changed if LENGTH is applied on null or a boolean value:

  • LENGTH(null) now returns 0. In previous versions of ArangoDB, this returned 4.

  • LENGTH(false) now returns 0. In previous versions of ArangoDB, the return value was 5.

  • LENGTH(true) now returns 1. In previous versions of ArangoDB, the return value was 4.

AQL graph functions

In 2.6 the graph functions did undergo a performance lifting. During this process we had to adopt the result format and the options for some of them. Many graph functions now have an option includeData which allows to trigger if the result of this function should contain fully extracted documents includeData: true or only the _id values includeData: false. In most use cases the _id is sufficient to continue and the extraction of data is an unnecessary operation. The AQL functions supporting this additional option are:

  • SHORTEST_PATH
  • NEIGHBORS
  • GRAPH_SHORTEST_PATH
  • GRAPH_NEIGHBORS
  • GRAPH_EDGES

Furthermore the result SHORTEST_PATH has changed. The old format returned a list of all vertices on the path. Optionally it could include each sub-path for these vertices. All of the documents were fully extracted. Example:

[
  {
    vertex: {
      _id: "vertex/1",
      _key: "1",
      _rev: "1234"
      name: "Alice"
    },
    path: {
      vertices: [
        {
          _id: "vertex/1",
          _key: "1",
          _rev: "1234"
          name: "Alice"
        }
      ],
      edges: []
    }
  },
  {
    vertex: {
      _id: "vertex/2",
      _key: "2",
      _rev: "5678"
      name: "Bob"
    },
    path: {
      vertices: [
        {
          _id: "vertex/1",
          _key: "1",
          _rev: "1234"
          name: "Alice"
        }, {
          _id: "vertex/2",
          _key: "2",
          _rev: "5678"
          name: "Bob"
        }
      ],
      edges: [
        {
          _id: "edge/1",
          _key: "1",
          _rev: "9876",
          type: "loves"
        }
      ]
    }
  }
]

The new version is more compact. Each SHORTEST_PATH will only return one document having the attributes vertices, edges, distance. The distance is computed taking into account the given weight. Optionally the documents can be extracted with includeData: true Example:

{
  vertices: [
    "vertex/1",
    "vertex/2"
  ],
  edges: [
    "edge/1"
  ],
  distance: 1
}

The next function that returns a different format is NEIGHBORS. Since 2.5 it returned an object with edge and vertex for each connected edge. Example:

[
  {
    vertex: {
      _id: "vertex/2",
      _key: "2",
      _rev: "5678"
      name: "Bob"
    },
    edge: {
      _id: "edge/1",
      _key: "1",
      _rev: "9876",
      type: "loves"
    }
  } 
]

With 2.6 it will only return the vertex directly, again using includeData: true. By default it will return a distinct set of neighbors, using the option distinct: false will include the same vertex for each edge pointing to it.

Example:

[
  "vertex/2"
]

Function and API changes

Graph measurements functions

All graph measurements functions in JavaScript module general-graph that calculated a single figure previously returned an array containing just the figure. Now these functions will return the figure directly and not put it inside an array.

The affected functions are:

  • graph._absoluteEccentricity
  • graph._eccentricity
  • graph._absoluteCloseness
  • graph._closeness
  • graph._absoluteBetweenness
  • graph._betweenness
  • graph._radius
  • graph._diameter

Client programs calling these functions should be adjusted so they process the scalar value returned by the function instead of the previous array value.

Cursor API

A batchSize value 0 is now disallowed when calling the cursor API via HTTP POST /_api/cursor.

The HTTP REST API POST /_api/cursor does not accept a batchSize parameter value of 0 any longer. A batch size of 0 never made much sense, but previous versions of ArangoDB did not check for this value. Now creating a cursor using a batchSize value 0 will result in an HTTP 400 error response.

Document URLs returned

The REST API method GET /_api/document?collection=... (that method will return partial URLs to all documents in the collection) will now properly prefix document address URLs with the current database name.

Previous versions of ArangoDB returned the URLs starting with /_api/ but without the current database name, e.g. /_api/document/mycollection/mykey. Starting with 2.6, the response URLs will include the database name as well, e.g. /_db/_system/_api/document/mycollection/mykey.

Fulltext indexing

Fulltext indexes will now also index text values contained in direct sub-objects of the indexed attribute.

Previous versions of ArangoDB only indexed the attribute value if it was a string. Sub-attributes of the index attribute were ignored when fulltext indexing.

Now, if the index attribute value is an object, the object's values will each be included in the fulltext index if they are strings. If the index attribute value is an array, the array's values will each be included in the fulltext index if they are strings.

Deprecated server functionality

Simple queries

The following simple query functions are now deprecated:

  • collection.near
  • collection.within
  • collection.geo
  • collection.fulltext
  • collection.range
  • collection.closedRange

This also lead to the following REST API methods being deprecated from now on:

  • PUT /_api/simple/near
  • PUT /_api/simple/within
  • PUT /_api/simple/fulltext
  • PUT /_api/simple/range

It is recommended to replace calls to these functions or APIs with equivalent AQL queries, which are more flexible because they can be combined with other operations:

FOR doc IN NEAR(@@collection, @latitude, @longitude, @limit) 
  RETURN doc

FOR doc IN WITHIN(@@collection, @latitude, @longitude, @radius, @distanceAttributeName)
  RETURN doc

FOR doc IN FULLTEXT(@@collection, @attributeName, @queryString, @limit) 
  RETURN doc

FOR doc IN @@collection 
  FILTER doc.value >= @left && doc.value < @right 
  LIMIT @skip, @limit 
  RETURN doc`

The above simple query functions and REST API methods may be removed in future versions of ArangoDB.

Using negative values for SimpleQuery.skip() is also deprecated. This functionality will be removed in future versions of ArangoDB.

AQL functions

The AQL SKIPLIST function has been deprecated because it is obsolete.

The function was introduced in older versions of ArangoDB with a less powerful query optimizer to retrieve data from a skiplist index using a LIMIT clause.

Since 2.3 the same goal can be achieved by using regular AQL constructs, e.g. 

FOR doc IN @@collection 
  FILTER doc.value >= @value 
  SORT doc.value
  LIMIT 1 
  RETURN doc

Startup option changes

Options added

The following configuration options have been added in 2.6:

  • --server.session-timeout: allows controlling the timeout of user sessions in the web interface. The value is specified in seconds.

  • --server.foxx-queues: controls whether the Foxx queue manager will check queue and job entries. Disabling this option can reduce server load but will prevent jobs added to Foxx queues from being processed at all.

    The default value is true, enabling the Foxx queues feature.

  • --server.foxx-queues-poll-interval: allows adjusting the frequency with which the Foxx queues manager is checking the queue (or queues) for jobs to be executed.

    The default value is 1 second. Lowering this value will result in the queue manager waking up and checking the queues more frequently, which may increase CPU usage of the server.

    Note: this option only has an effect when --server.foxx-queues is not set to false.

Options removed

The following configuration options have been removed in 2.6.:

  • --log.severity: the docs for --log.severity mentioned lots of severities (e.g. exception, technical, functional, development) but only a few severities (e.g. all, human) were actually used, with human being the default and all enabling the additional logging of incoming requests.

    The option pretended to control a lot of things which it actually didn't. Additionally, the option --log.requests-file was around for a long time already, also controlling request logging.

    Because the --log.severity option effectively did not control that much, it was removed. A side effect of removing the option is that 2.5 installations started with option --log.severity all will not log requests after the upgrade to 2.6. This can be adjusted by setting the --log.requests-file option instead.

Default values changed

The default values for the following options have changed in 2.6:

  • --database.ignore-datafile-errors: the default value for this option was changed from true to false.

    If the new default value of false is used, then arangod will refuse loading collections that contain datafiles with CRC mismatches or other errors. A collection with datafile errors will then become unavailable. This prevents follow up errors from happening.

    The only way to access such collection is to use the datafile debugger (arango-dfdb) and try to repair or truncate the datafile with it.

  • --server.request-timeout: the default value was increased from 300 to 1200 seconds for all client tools (arangosh, arangoimp, arangodump, arangorestore).

  • --server.connect-timeout: the default value was increased from 3 to 5 seconds for all client tools (arangosh, arangoimp, arangodump, arangorestore).

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