Collection Methods

Drop

Drops a collection:

collection.drop(options)

Drops a collection and all its indexes and data. In order to drop a system collection, an options object with attribute isSystem set to true must be specified.

Dropping a collection in a cluster, which is prototype for sharing in other collections is prohibited. In order to be able to drop such a collection, all dependent collections must be dropped first.

Examples

Drop a collection:

arangosh> col = db.example;
arangosh> col.drop();
arangosh> col;
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[ArangoCollection 73840, "example" (type document, status loaded)]
[ArangoCollection 73840, "example" (type document, status deleted)]

Drop a system collection:

arangosh> col = db._example;
arangosh> col.drop({ isSystem: true });
arangosh> col;
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[ArangoCollection 73847, "_example" (type document, status loaded)]
[ArangoCollection 73847, "_example" (type document, status deleted)]

Truncate

Truncate a collection:

collection.truncate()

Truncates a collection, removing all documents but keeping all its indexes.

Examples

Truncates a collection:

arangosh> col = db.example;
arangosh> col.save({ "Hello" : "World" });
arangosh> col.count();
arangosh> col.truncate();
arangosh> col.count();
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[ArangoCollection 74003, "example" (type document, status loaded)]
{ 
  "_id" : "example/74008", 
  "_key" : "74008", 
  "_rev" : "_fdPEMNu--_" 
}
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Compact

Compacts the data of a collection:

collection.compact()

Compacts the data of a collection in order to reclaim disk space. The operation compacts the document and index data by rewriting the underlying .sst files and only keeps the relevant entries.

Under normal circumstances running a compact operation is not necessary, as the collection data is eventually compacted anyway. However, in some situations, e.g. after running lots of update/replace or remove operations, the disk data for a collection may contain a lot of outdated data for which the space shall be reclaimed. In this case the compaction operation can be used.

Properties

Get or set the properties of a collection:

collection.properties()

Returns an object containing all collection properties.

  • waitForSync (boolean): If true, creating, changing, or removing documents waits until the data has been synchronized to disk.

  • keyOptions (object): An object which contains key generation options.
    • type (string): Specifies the type of the key generator. Possible values:
      • "traditional"
      • "autoincrement"
      • "uuid"
      • "padded"
    • allowUserKeys (boolean): If set to true, then you are allowed to supply own key values in the _key attribute of documents. If set to false, then the key generator is solely responsible for generating keys and an error is raised if you supply own key values in the _key attribute of documents.
    • increment (number): The increment value for the autoincrement key generator. Not used for other key generator types.
    • offset (number): The initial offset value for the autoincrement key generator. Not used for other key generator types.
    • lastValue (number): the current offset value of the autoincrement or padded key generator. This an internal property for restoring dumps properly.
  • schema (object|null): An object that specifies the collection-level document schema for documents. The attribute keys rule, level and message must follow the rules documented in Document Schema Validation

  • computedValues (array|null): An array of objects, each representing a Computed Value.

  • cacheEnabled (boolean): Whether the in-memory hash cache for documents is enabled for this collection (default: false).

  • isSystem (boolean): Whether the collection is a system collection. Collection names that starts with an underscore are usually system collections.

  • syncByRevision (boolean): Whether the newer revision-based replication protocol is enabled for this collection. This is an internal property.

  • globallyUniqueId (string): A unique identifier of the collection. This is an internal property.

In a cluster setup, the result also contains the following attributes:

  • numberOfShards (number): The number of shards of the collection.

  • shardKeys (array): Contains the names of document attributes that are used to determine the target shard for documents.

  • replicationFactor (number|string): Determines how many copies of each shard are kept on different DB-Servers. Has to be in the range of 1-10 or the string "satellite" for a SatelliteCollection (Enterprise Edition only). (cluster only)

  • writeConcern (number): Determines how many copies of each shard are required to be in sync on the different DB-Servers. If there are less then these many copies in the cluster, a shard refuses to write. Writes to shards with enough up-to-date copies succeed at the same time, however. The value of writeConcern can not be larger than replicationFactor. (cluster only)

  • shardingStrategy (string): the sharding strategy selected for the collection. (cluster only)

    Possible values:

    • "community-compat"
    • "enterprise-compat"
    • "enterprise-smart-edge-compat"
    • "hash"
    • "enterprise-hash-smart-edge"
    • "enterprise-hex-smart-vertex"
  • distributeShardsLike (string): The name of another collection. This collection uses the replicationFactor, numberOfShards and shardingStrategy properties of the other collection and the shards of this collection are distributed in the same way as the shards of the other collection.

  • isSmart (boolean): Whether the collection is used in a SmartGraph or EnterpriseGraph (Enterprise Edition only). This is an internal property.

  • isDisjoint (boolean): Whether the SmartGraph this collection belongs to is disjoint (Enterprise Edition only). This is an internal property.

  • smartGraphAttribute (string): The attribute that is used for sharding: vertices with the same value of this attribute are placed in the same shard. All vertices are required to have this attribute set and it has to be a string. Edges derive the attribute from their connected vertices.

    This feature can only be used in the Enterprise Edition.

  • smartJoinAttribute (string): In an Enterprise Edition cluster, this attribute determines an attribute of the collection that must contain the shard key value of the referred-to SmartJoin collection.


collection.properties(properties)

Changes the collection properties. properties must be an object and can have one or more of the following attribute(s):

  • waitForSync (boolean): If true, creating a document only returns after the data was synced to disk.

  • replicationFactor (number|string): Change the number of shard copies kept on different DB-Servers. Valid values are integer numbers in the range of 1-10 or the string "satellite" for a SatelliteCollection (Enterprise Edition only). (cluster only)

  • writeConcern (number): Change how many copies of each shard are required to be in sync on the different DB-Servers. If there are less then these many copies in the cluster, a shard refuses to write. Writes to shards with enough up-to-date copies succeed at the same time however. The value of writeConcern can not be larger than replicationFactor. (cluster only)

  • computedValues (array|null): An array of objects, each representing a Computed Value.

  • schema (object|null): An object that specifies the collection level document schema for documents. The attribute keys rule, level and message must follow the rules documented in Document Schema Validation

  • cacheEnabled (boolean): Whether the in-memory hash cache for documents should be enabled for this collection. Can be controlled globally with the --cache.size startup option. The cache can speed up repeated reads of the same documents via their document keys. If the same documents are not fetched often or are modified frequently, then you may disable the cache to avoid the maintenance costs.

Some other collection properties, such as type, keyOptions, numberOfShards or shardingStrategy cannot be changed once the collection is created.

Examples

Read all properties:

arangosh> db.example.properties();
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{ 
  "globallyUniqueId" : "h46B1CCFFDD54/73958", 
  "isSystem" : false, 
  "waitForSync" : false, 
  "keyOptions" : { 
    "allowUserKeys" : true, 
    "type" : "traditional", 
    "lastValue" : 0 
  }, 
  "writeConcern" : 1, 
  "cacheEnabled" : false, 
  "computedValues" : null, 
  "syncByRevision" : true, 
  "schema" : null 
}

Change a property:

arangosh> db.example.properties({ waitForSync : true });
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{ 
  "globallyUniqueId" : "h46B1CCFFDD54/73966", 
  "isSystem" : false, 
  "waitForSync" : true, 
  "keyOptions" : { 
    "allowUserKeys" : true, 
    "type" : "traditional", 
    "lastValue" : 0 
  }, 
  "writeConcern" : 1, 
  "cacheEnabled" : false, 
  "computedValues" : null, 
  "syncByRevision" : true, 
  "schema" : null 
}

Figures

Return the figures of a collection:

collection.figures(details)

Returns an object containing statistics about the collection.

Setting details to true returns extended storage engine-specific details to the figures (introduced in v3.8.0). The details are intended for debugging ArangoDB itself and their format is subject to change. By default, details is set to false, so no details are returned and the behavior is identical to previous versions of ArangoDB.

  • indexes.count: The total number of indexes defined for the collection, including the pre-defined indexes (e.g. primary index).
  • indexes.size: The total memory allocated for indexes in bytes.
  • documentsSize
  • cacheInUse
  • cacheSize
  • cacheUsage

Examples

Get the basic collection figures:

arangosh> db.demo.figures()
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{ 
  "indexes" : { 
    "count" : 1, 
    "size" : 2079 
  }, 
  "documentsSize" : 11777, 
  "cacheInUse" : false, 
  "cacheSize" : 0, 
  "cacheUsage" : 0 
}

Get the detailed collection figures:

arangosh> db.demo.figures(true)
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{ 
  "indexes" : { 
    "count" : 1, 
    "size" : 2079 
  }, 
  "documentsSize" : 11777, 
  "cacheInUse" : false, 
  "cacheSize" : 0, 
  "cacheUsage" : 0, 
  "engine" : { 
    "documents" : 1, 
    "indexes" : [ 
      { 
        "type" : "primary", 
        "id" : 0, 
        "count" : 1 
      } 
    ] 
  } 
}

GetResponsibleShard

Return the responsible shard for the given document:

collection.getResponsibleShard(document)

Returns a string with the responsible shard’s ID. Note that the returned shard ID is the ID of responsible shard for the document’s shard key values, and it returns even if no such document exists.

The getResponsibleShard() method can only be used on Coordinators in clusters.

Shards

Return the available shards for the collection:

collection.shards(details)

If details is not set, or set to false, returns an array with the names of the available shards of the collection.

If details is set to true, returns an object with the shard names as object attribute keys, and the responsible servers as an array mapped to each shard attribute key.

The leader shards are always first in the arrays of responsible servers.

The shards() method can only be used on Coordinators in clusters.

Load

Load a collection:

collection.load()

Loads a collection into memory.

Cluster collections are loaded at all times.

The load() function is deprecated as of ArangoDB 3.8.0. The function may be removed in future versions of ArangoDB. There should not be any need to load a collection with the RocksDB storage engine.

Examples

arangosh> col = db.example;
arangosh> col.load();
arangosh> col;
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[ArangoCollection 73931, "example" (type document, status loaded)]
[ArangoCollection 73931, "example" (type document, status loaded)]

Revision

Return the revision ID of a collection:

collection.revision()

Returns the revision ID of the collection

The revision ID is updated when the document data is modified, either by inserting, deleting, updating or replacing documents in it.

The revision ID of a collection can be used by clients to check whether data in a collection has changed or if it is still unmodified since a previous fetch of the revision ID.

The revision ID returned is a string value. Clients should treat this value as an opaque string, and only use it for equality/non-equality comparisons.

Checksum

Calculate a checksum for the data in a collection:

collection.checksum(withRevisions, withData)

The checksum operation calculates an aggregate hash value for all document keys contained in collection collection.

If the optional argument withRevisions is set to true, then the revision ids of the documents are also included in the hash calculation.

If the optional argument withData is set to true, then all user-defined document attributes are also checksummed. Including the document data in checksumming makes the calculation slower, but is more accurate.

Unload

Unload a collection:

collection.unload()

Starts unloading a collection from memory. Note that unloading is deferred until all queries have finished.

Cluster collections cannot be unloaded.

The unload() function is deprecated as of ArangoDB 3.8.0. The function may be removed in future versions of ArangoDB. There should not be any need to unload a collection with the RocksDB storage engine.

Examples

arangosh> col = db.example;
arangosh> col.unload();
arangosh> col;
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[ArangoCollection 61264, "example" (type document, status loaded)]
[ArangoCollection 61264, "example" (type document, status loaded)]

Rename

Rename a collection:

collection.rename(new-name)

Renames a collection using the new-name. The new-name must not already be used for a different collection. new-name must also be a valid collection name. For more information on valid collection names please refer to the naming conventions.

If renaming fails for any reason, an error is thrown. If renaming the collection succeeds, then the collection is also renamed in all graph definitions inside the _graphs collection in the current database.

The rename() method can not be used in clusters.

Examples

arangosh> c = db.example;
arangosh> c.rename("better-example");
arangosh> c;
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[ArangoCollection 73994, "example" (type document, status loaded)]
[ArangoCollection 73994, "better-example" (type document, status loaded)]