Session: Querying: How to Customize a Query
The following query customization options are available in the IDocumentQueryCustomization
interface:
- BeforeQueryExecuted
- AfterQueryExecuted
- AfterStreamExecuted
- NoCaching
- NoTracking
- RandomOrdering
- WaitForNonStaleResults
BeforeQueryExecuted
Allows you to modify the index query just before it's executed.
IDocumentQueryCustomization addBeforeQueryExecutedListener(Consumer<IndexQuery> action);
IDocumentQueryCustomization removeBeforeQueryExecutedListener(Consumer<IndexQuery> action);
Parameters | ||
---|---|---|
action | Consumer |
Action that will modify IndexQuery. |
Return Value | |
---|---|
IDocumentQueryCustomization | Returns self for easier method chaining. |
Example
session.advanced().addBeforeQueryListener(
(sender, event) -> event.getQueryCustomization().addBeforeQueryExecutedListener(
// set 'pageSize' to 10
q -> q.setPageSize(10)));
session
.query(Employee.class)
.toList();
AfterQueryExecuted
Allows you to retrieve a raw query result after it's executed.
IDocumentQueryCustomization addAfterQueryExecutedListener(Consumer<QueryResult> action);
IDocumentQueryCustomization removeAfterQueryExecutedListener(Consumer<QueryResult> action);
Parameters | ||
---|---|---|
action | Consumer |
Action that has the query result. |
Return Value | |
---|---|
IDocumentQueryCustomization | Returns self for easier method chaining. |
Example
AtomicReference<Duration> queryDuration = new AtomicReference<>();
session.query(Employee.class)
.addAfterQueryExecutedListener(result -> {
queryDuration.set(Duration.ofMillis(result.getDurationInMs()));
})
.toList();
AfterStreamExecuted
Allows you to retrieve a raw result of the streaming query.
IDocumentQueryCustomization addAfterStreamExecutedListener(Consumer<ObjectNode> action);
IDocumentQueryCustomization removeAfterStreamExecutedListener(Consumer<ObjectNode> action);
Parameters | ||
---|---|---|
action | Consumer |
Action that has the single query result. |
Return Value | |
---|---|
IDocumentQueryCustomization | Returns self for easier method chaining. |
Example
Reference<Long> totalStreamedResultsSize = new Reference<>(0L);
session.query(Employee.class)
.addAfterStreamExecutedListener(result -> {
totalStreamedResultsSize.value += result.size();
})
.toList();
NoCaching
By default, queries are cached. To disable query caching use the noCaching
customization.
IDocumentQueryCustomization noCaching();
Return Value | |
---|---|
IDocumentQueryCustomization | Returns self for easier method chaining. |
Example
session.advanced().addBeforeQueryListener(
((sender, event) -> event.getQueryCustomization().noCaching()));
List<Employee> results = session.query(Employee.class)
.whereEquals("FirstName", "Robert")
.toList();
NoTracking
To disable entity tracking by session
use noTracking
. Usage of this option will prevent holding the query results in memory.
IDocumentQueryCustomization noTracking();
Return Value | |
---|---|
IDocumentQueryCustomization | Returns self for easier method chaining. |
Example
session.advanced().addBeforeQueryListener(
((sender, event) -> event.getQueryCustomization().noTracking()));
List<Employee> results = session.query(Employee.class)
.whereEquals("FirstName", "Robert")
.toList();
RandomOrdering
To order results randomly, use the randomOrdering
method.
IDocumentQueryCustomization randomOrdering();
IDocumentQueryCustomization randomOrdering(String seed);
Parameters | ||
---|---|---|
seed | String | Seed used for ordering. Useful when repeatable random queries are needed. |
Return Value | |
---|---|
IDocumentQueryCustomization | Returns self for easier method chaining. |
Example
session.advanced().addBeforeQueryListener(
(sender, event) -> event.getQueryCustomization().randomOrdering());
//result will be ordered randomly each time
List<Employee> results = session.query(Employee.class)
.whereEquals("FirstName", "Robert")
.toList();
WaitForNonStaleResults
Queries can be 'instructed' to wait for non-stale results for a specified amount of time using the WaitForNonStaleResults
method. If the query won't be able to return
non-stale results within the specified (or default) timeout, then a TimeoutException
is thrown.
Cutoff Point
If a query sent to the server specifies that it needs to wait for non-stale results, then RavenDB sets the cutoff Etag for the staleness check. It is the Etag of the last document (or document tombstone), from the collection(s) processed by the index, as of the query arrived to the server. This way the server won't be waiting forever for the non-stale results even though documents are constantly updated meanwhile.
If the last Etag processed by the index is greater than the cutoff then the results are considered as non-stale.
IDocumentQueryCustomization waitForNonStaleResults();
IDocumentQueryCustomization waitForNonStaleResults(Duration waitTimeout);
Parameters | ||
---|---|---|
waitTimeout | Duration | Time to wait for an index to return non-stale results. The default is 15 seconds. |
Return Value | |
---|---|
IDocumentQueryCustomization | Returns self for easier method chaining. |
Example
session.advanced().addBeforeQueryListener(
(sender, event) -> event.getQueryCustomization().waitForNonStaleResults());
List<Employee> results = session.query(Employee.class)
.whereEquals("FirstName", "Robert")
.toList();