21.12. Querying for entities modified in a given revision

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The basic query allows retrieving entity names and corresponding Java classes changed in a specified revision:

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<pre class="prettyprint highlight">`modifiedEntityTypes = getAuditReader()
    .getCrossTypeRevisionChangesReader()
    .findEntityTypes( revisionNumber );`</pre>
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Other queries (also accessible from `org.hibernate.envers.CrossTypeRevisionChangesReader`):

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<dt class="hdlist1">`List&lt;Object&gt; findEntities( Number )`</dt>
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Returns snapshots of all audited entities changed (added, updated and removed) in a given revision.
Executes `N+1` SQL queries, where `N` is a number of different entity classes modified within specified revision.

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<dt class="hdlist1">`List&lt;Object&gt; findEntities( Number, RevisionType )`</dt>
<dd>

Returns snapshots of all audited entities changed (added, updated or removed) in a given revision filtered by modification type.
Executes `N+1` SQL queries, where `N` is a number of different entity classes modified within specified revision.

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<dt class="hdlist1">`Map&lt;RevisionType, List&lt;Object&gt;&gt; findEntitiesGroupByRevisionType( Number )`</dt>
<dd>

Returns a map containing lists of entity snapshots grouped by modification operation (e.g. addition, update and removal).
Executes `3N+1` SQL queries, where `N` is a number of different entity classes modified within specified revision.

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Note that methods described above can be legally used only when the default mechanism of tracking changed entity names is enabled (see [Tracking entity names modified during revisions](#envers-tracking-modified-entities-revchanges)).

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