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Collection Strategies
Doctrine MongoDB ODM implements four different strategies for persisting changes to collections of embedded documents or references. These strategies apply to the following mapping types:
Internally, Doctrine tracks changes via the PersistentCollection class. The strategies described on this page are implemented by the CollectionPersister class.
addToSet
The addToSet strategy uses MongoDB's $addToSet operator to insert
elements into the array. This strategy is useful for ensuring that duplicate
values will not be inserted into the collection. Like the pushAll strategy,
elements are inserted in a separate query after removing deleted elements.
set
The set strategy uses MongoDB's $set operator to update the entire
collection with a single update query.
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Doctrine's Collection interface is modeled after PHP's associative arrays,
so they cannot always be represented as a BSON array. If the collection's
keys are not sequential integers starting with zero, the |
setArray
The setArray strategy uses MongoDB's $set operator, just like the set
strategy, but will first numerically reindex the collection to ensure that it is
stored as a BSON array.
pushAll
The pushAll strategy uses MongoDB's $pushAll operator to insert
elements into the array. MongoDB does not allow elements to be added and removed
from an array in a single operation, so this strategy relies on multiple update
queries to remove and insert elements (in that order).
atomicSet
The atomicSet strategy uses MongoDB's $set operator to update the entire
collection with a single update query. Unlike with set strategy there will
be only one query for updating both parent document and collection itself. This
strategy can be especially useful when dealing with high concurrency and
versioned documents.
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atomicSetArray
The atomicSetArray strategy works exactly like atomicSet strategy, but
will first numerically reindex the collection to ensure that it is stored as a
BSON array.
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