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@startDocuBlock collectionProperties
@brief gets or sets the properties of a collection
collection.properties()
Returns an object containing all collection properties.
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waitForSync: If true creating a document will only return after the data was synced to disk.
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journalSize : The size of the journal in bytes. This option is meaningful for the MMFiles storage engine only.
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isVolatile: If true then the collection data will be kept in memory only and ArangoDB will not write or sync the data to disk. This option is meaningful for the MMFiles storage engine only.
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keyOptions (optional) additional options for key generation. This is a JSON array containing the following attributes (note: some of the attributes are optional):
- type: the type of the key generator used for the collection.
- allowUserKeys: if set to true, then it is allowed to supply own key values in the _key attribute of a document. If set to false, then the key generator will solely be responsible for generating keys and supplying own key values in the _key attribute of documents is considered an error.
- increment: increment value for autoincrement key generator. Not used for other key generator types.
- offset: initial offset value for autoincrement key generator. Not used for other key generator types.
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indexBuckets: number of buckets into which indexes using a hash table are split. The default is 16 and this number has to be a power of 2 and less than or equal to 1024. This option is meaningful for the MMFiles storage engine only.
For very large collections one should increase this to avoid long pauses when the hash table has to be initially built or resized, since buckets are resized individually and can be initially built in parallel. For example, 64 might be a sensible value for a collection with 100 000 000 documents. Currently, only the edge index respects this value, but other index types might follow in future ArangoDB versions. Changes (see below) are applied when the collection is loaded the next time.
In a cluster setup, the result will also contain the following attributes:
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numberOfShards: the number of shards of the collection.
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shardKeys: contains the names of document attributes that are used to determine the target shard for documents.
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replicationFactor: determines how many copies of each shard are kept on different DBServers. Has to be in the range of 1-10 (Cluster only)
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minReplicationFactor : determines the number of minimal shard copies kept on different DBServers, a shard will refuse to write if less than this amount of copies are in sync. Has to be in the range of 1-replicationFactor (Cluster only)
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shardingStrategy: the sharding strategy selected for the collection. This attribute will only be populated in cluster mode and is not populated in single-server mode.
collection.properties(properties)
Changes the collection properties. properties must be an object with one or more of the following attribute(s):
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waitForSync: If true creating a document will only return after the data was synced to disk.
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journalSize : The size of the journal in bytes. This option is meaningful for the MMFiles storage engine only.
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indexBuckets : See above, changes are only applied when the collection is loaded the next time. This option is meaningful for the MMFiles storage engine only.
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replicationFactor : Change the number of shard copies kept on different DBServers, valid values are integer numbers in the range of 1-10 (Cluster only)
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minReplicationFactor : Change the number of minimal shard copies to be in sync on different DBServers, a shard will refuse to write if less than this amount of copies are in sync. Has to be in the range of 1-replicationFactor (Cluster only)
Note: some other collection properties, such as type, isVolatile, keyOptions, numberOfShards or shardingStrategy cannot be changed once the collection is created.
@EXAMPLES
Read all properties
@EXAMPLE_ARANGOSH_OUTPUT{collectionProperties} ~ db._create("example"); db.example.properties(); ~ db._drop("example"); @END_EXAMPLE_ARANGOSH_OUTPUT
Change a property
@EXAMPLE_ARANGOSH_OUTPUT{collectionProperty} ~ db._create("example"); db.example.properties({ waitForSync : true }); ~ db._drop("example"); @END_EXAMPLE_ARANGOSH_OUTPUT
@endDocuBlock