Capped Collections

Capped collections are fixed sized collections that have a very high performance auto-LRU age-out feature (age out is based on insertion order).

In addition, capped collections automatically, with high performance, maintain insertion order for the objects in the collection; this is very powerful for certain use cases such as logging.

Mapping

You can configure the collection in the collection attribute of the @Document annotation:

• PHP

  <?php
  
  /**
   * @Document(collection={
   *   "name"="collname",
   *   "capped"=true,
   *   "size"=100000,
   *   "max"=1000
   * })
   */
  class Category
  {
      /** @Id */
      public $id;
  
      /** @Field(type="string") */
      public $name;
  }
  

• XML

  <?xml version="1.0" encoding="UTF-8"?>
  <doctrine-mongo-mapping xmlns="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping"
                    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                    xsi:schemaLocation="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping
                    http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping.xsd">
      <document name="Documents\Category" collection="collname" capped-collection="true" capped-collection-size="100000" capped-collection-max="1000">
          <field fieldName="id" id="true" />
          <field fieldName="name" type="string" />
      </document>
  </doctrine-mongo-mapping>
  

• YAML

  Documents\Category:
    type: document
    collection:
      name: collname
      capped: true
      size: 100000
      max: 1000
    fields:
      id:
        type: id
        id: true
      name:
        type: string
  

Creating

Remember that you must manually create the collections. If you let MongoDB create the collection lazily the first time it is selected, it will not be created with the capped configuration. You can create the collection for a document with the SchemaManager that can be acquired from your DocumentManager instance:

<?php

$documentManager->getSchemaManager()->createDocumentCollection('Category');

You can drop the collection too if it already exists:

<?php

$documentManager->getSchemaManager()->dropDocumentCollection('Category');