Incompatible changes in ArangoDB 3.1

    The internal commication layer is now based on Boost ASIO. A few optionsregarding threads and communication have been changed.

    There are no longer two different threads pools ( and—server.threads). The option —scheduler.threads has been removed. The number of threads is now controlled by the option —server.threads only.By default —server.threads is set to the number of hyper-cores.

    As a consequence of the change, the following (hidden) startup options have been removed:

    • —server.extra-threads
    • —server.aql-threads
    • —server.backend
    • —server.show-backends
    • —server.thread-affinity

    The behavior of the AQL array comparison operators has changed for empty arrays:

    • NONE now always returns true when the left-hand operand is an empty array.The behavior for non-empty arrays does not change:
      • [] NONE == 1 will return true
      • [1] NONE == 1 will return false
      • [1, 2] NONE == 1 will return false
    • WITH in cluster traversals is now mandatory in order to avoid deadlocks.

    The attribute maximalSize has been renamed to journalSize in collectionmeta-data files (“parameter.json”). Files containing the maximalSize attribute will still be picked up correctly for not-yet adjusted collections.

    ArangoDB >= 3.1 can ArangoDB 3.0 database directories and will simply continueto use the old _rev attribute values. New revisions will be written withthe new time stamps.

    It is highly recommended to backup all your data before loading a databasedirectory that was written by ArangoDB <= 3.0 into an ArangoDB >= 3.1.

    To change all your old _rev attributes into new style time stamps youhave to use arangodump to dump all data out (using ArangoDB 3.0), and use arangorestore into the new ArangoDB 3.1, which is the safestway to upgrade.

    The change also affects the return format of _rev values and other revisionvalues in HTTP APIs (see below).

    The following HTTP REST APIs have been added for online loglevel adjustment ofthe server:

    • GET /_admin/log/level returns the current loglevel settings
    • PUT /_admin/log/level modifies the current loglevel settings

    APIs changed

    • the following REST APIs that return revision ids now make use of the new revisionid format introduced in 3.1. All revision ids returned will be strings as in 3.0, buthave a different internal format.
    • GET /_api/collection/{collection}/checksum: revision attribute
    • GET /_api/collection/{collection}/revision: revision attribute
    • all other APIs that return documents, which may include the documents’ _rev attributeClient applications should not try to interpret the internals of revision values, but only use revision values for checking whether two revision strings are identical.

    • the replication REST APIs will now use the attribute name instead ofmaximalSize when returning information about collections.

    • the default value for keepNull has been changed from false to true for the following partial update operations for vertices and edges in /_api/gharial:

      • PATCH /_api/gharial/{graph}/vertex/{collection}/{key}
      • PATCH /_api/gharial/{graph}/edge/{collection}/{key}The value for keepNull can still be set explicitly to false by setting theURL parameter keepNull to a value of false.

    • the REST API for dropping collections (DELETE /_api/collection) now accepts anoptional query string parameter isSystem, which can set to true in order todrop system collections. If the parameter is not set or not set to true, the RESTAPI will refuse to drop system collections. In previous versions of ArangoDB, theisSystem parameter did not exist, and there was no distinction between system and non-system collections when dropping collections.

    The QUnit interface to Mocha has been removed. This affects the behavior of the suite, test, before, after, beforeEach and afterEach functions in Foxx test suites. The suite and test functions are now provided by the TDD interface. The before, after, beforeEach and afterEach functions are now provided by the BDD interface.

    For details on the expected behavior of these functions see the in the Foxx documentation.