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## Oak Query

Oak does not index as much content by default as does Jackrabbit
2. You need to create custom indexes when necessary, much like in
traditional RDBMSs. If there is no index for a specific query, then
the repository will be traversed. That is, the query will still work
but probably be very slow.

* [The Query Engine](./query-engine.html)
* [XPath Grammar](./grammar-xpath.html)
* [SQL-2 Grammar](./grammar-sql2.html)
* [Troubleshooting](./query-troubleshooting.html)
* [Flags](./flags.html)

### Indexes

There are 4 main types of indexes available in Oak. For other type
(eg: nodetype) please refer to the [query engine](./query-engine.html)
documentation page.

* [Lucene](./lucene.html)
* [Elastic](./elastic.html)
* [Property](./property-index.html)
* [Solr](./solr.html) (*NOTE:* Solr support has been removed in Oak 1.82 (see [OAK-11346](https://issues.apache.org/jira/browse/OAK-11346))

For more details on how indexing works (for all index types):

* [Indexing](indexing.html) 
* [Reindexing](indexing.html#Reindexing)

### Customisations

* [Change Out-Of-The-Box Index Definitions](./ootb-index-change.html)
* [Machine Translation for Search](./search-mt.html)


