mirror of https://gitee.com/bigwinds/arangodb
92 lines
3.3 KiB
Markdown
92 lines
3.3 KiB
Markdown
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@startDocuBlock collectionProperties
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@brief gets or sets the properties of a collection
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`collection.properties()`
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Returns an object containing all collection properties.
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* *waitForSync*: If *true* creating a document will only return
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after the data was synced to disk.
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* *journalSize* : The size of the journal in bytes.
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* *isVolatile*: If *true* then the collection data will be
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kept in memory only and ArangoDB will not write or sync the data
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to disk.
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* *keyOptions* (optional) additional options for key generation. This is
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a JSON array containing the following attributes (note: some of the
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attributes are optional):
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* *type*: the type of the key generator used for the collection.
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* *allowUserKeys*: if set to *true*, then it is allowed to supply
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own key values in the *_key* attribute of a document. If set to
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*false*, then the key generator will solely be responsible for
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generating keys and supplying own key values in the *_key* attribute
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of documents is considered an error.
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* *increment*: increment value for *autoincrement* key generator.
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Not used for other key generator types.
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* *offset*: initial offset value for *autoincrement* key generator.
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Not used for other key generator types.
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* *indexBuckets*: number of buckets into which indexes using a hash
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table are split. The default is 16 and this number has to be a
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power of 2 and less than or equal to 1024.
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For very large collections one should increase this to avoid long pauses
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when the hash table has to be initially built or resized, since buckets
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are resized individually and can be initially built in parallel. For
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example, 64 might be a sensible value for a collection with 100
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000 000 documents. Currently, only the edge index respects this
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value, but other index types might follow in future ArangoDB versions.
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Changes (see below) are applied when the collection is loaded the next
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time.
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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
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determine the target shard for documents.
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`collection.properties(properties)`
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Changes the collection properties. *properties* must be a object with
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one or more of the following attribute(s):
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* *waitForSync*: If *true* creating a document will only return
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after the data was synced to disk.
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* *journalSize* : The size of the journal in bytes.
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* *indexBuckets* : See above, changes are only applied when the
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collection is loaded the next time.
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*Note*: it is not possible to change the journal size after the journal or
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datafile has been created. Changing this parameter will only effect newly
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created journals. Also note that you cannot lower the journal size to less
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then size of the largest document already stored in the collection.
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**Note**: some other collection properties, such as *type*, *isVolatile*,
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or *keyOptions* cannot be changed once the collection is created.
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@EXAMPLES
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Read all properties
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@EXAMPLE_ARANGOSH_OUTPUT{collectionProperties}
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~ db._create("example");
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db.example.properties();
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~ db._drop("example");
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@END_EXAMPLE_ARANGOSH_OUTPUT
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Change a property
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@EXAMPLE_ARANGOSH_OUTPUT{collectionProperty}
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~ db._create("example");
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db.example.properties({ waitForSync : true });
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~ db._drop("example");
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@END_EXAMPLE_ARANGOSH_OUTPUT
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@endDocuBlock
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