ReadPreference

java.lang.Object
- com.mongodb.ReadPreference

Direct Known Subclasses:

TaggableReadPreference
```
@Immutable
public abstract class ReadPreference
extends Object
```
A class that represents preferred replica set members to which a query or command can be sent.

MongoDB documentation
Read Preference

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`List<ServerDescription>`	`choose(ClusterDescription clusterDescription)`	Chooses the servers from the given cluster than match this read preference.
`protected abstract List<ServerDescription>`	`chooseForNonReplicaSet(ClusterDescription clusterDescription)`
`protected abstract List<ServerDescription>`	`chooseForReplicaSet(ClusterDescription clusterDescription)`
`abstract String`	`getName()`	Gets the name of this read preference.
`abstract boolean`	`isSlaveOk()`	True if this read preference allows reading from a secondary member of a replica set.
`static ReadPreference`	`nearest()`	Gets a read preference that forces reads to a primary or a secondary.
`static ReadPreference`	`nearest(long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to a primary or a secondary that is less stale than the given maximum.
`static TaggableReadPreference`	`nearest(TagSet tagSet)`	Gets a read preference that forces reads to the primary or a secondary with the given set of tags.
`static TaggableReadPreference`	`nearest(TagSet tagSet, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to the primary or a secondary with the given set of tags that is less stale than the given maximum.
`static TaggableReadPreference`	`nearest(List<TagSet> tagSetList)`	Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`nearest(List<TagSet> tagSetList, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags that is less stale than the given maximum.
`static ReadPreference`	`primary()`	Gets a read preference that forces read to the primary.
`static ReadPreference`	`primaryPreferred()`	Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
`static ReadPreference`	`primaryPreferred(long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
`static TaggableReadPreference`	`primaryPreferred(TagSet tagSet)`	Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags.
`static TaggableReadPreference`	`primaryPreferred(TagSet tagSet, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags that is less stale than the given maximum.
`static TaggableReadPreference`	`primaryPreferred(List<TagSet> tagSetList)`	Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`primaryPreferred(List<TagSet> tagSetList, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags that is less stale than the given maximum.
`static ReadPreference`	`secondary()`	Gets a read preference that forces reads to a secondary.
`static ReadPreference`	`secondary(long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to a secondary that is less stale than the given maximum.
`static TaggableReadPreference`	`secondary(TagSet tagSet)`	Gets a read preference that forces reads to a secondary with the given set of tags.
`static TaggableReadPreference`	`secondary(TagSet tagSet, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to a secondary with the given set of tags that is less stale than the given maximum.
`static TaggableReadPreference`	`secondary(List<TagSet> tagSetList)`	Gets a read preference that forces reads to a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`secondary(List<TagSet> tagSetList, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to a secondary with one of the given sets of tags that is less stale than the given maximum.
`static ReadPreference`	`secondaryPreferred()`	Gets a read preference that forces reads to a secondary if one is available, otherwise to the primary.
`static ReadPreference`	`secondaryPreferred(long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to a secondary that is less stale than the given maximumm if one is available, otherwise to the primary.
`static TaggableReadPreference`	`secondaryPreferred(TagSet tagSet)`	Gets a read preference that forces reads to a secondary with the given set of tags, or the primary is none are available.
`static TaggableReadPreference`	`secondaryPreferred(TagSet tagSet, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to a secondary with the given set of tags that is less stale than the given maximum, or the primary is none are available.
`static TaggableReadPreference`	`secondaryPreferred(List<TagSet> tagSetList)`	Gets a read preference that forces reads to a secondary with one of the given sets of tags.
`static TaggableReadPreference`	`secondaryPreferred(List<TagSet> tagSetList, long maxStaleness, TimeUnit timeUnit)`	Gets a read preference that forces reads to a secondary with one of the given sets of tags that is less stale than the given maximum.
`abstract BsonDocument`	`toDocument()`	Gets a document representing this read preference in the wire protocol.
`static ReadPreference`	`valueOf(String name)`	Creates a read preference from the given read preference name.
`static TaggableReadPreference`	`valueOf(String name, List<TagSet> tagSetList)`	Creates a taggable read preference from the given read preference name and list of tag sets.
`static TaggableReadPreference`	`valueOf(String name, List<TagSet> tagSetList, long maxStaleness, TimeUnit timeUnit)`	Creates a taggable read preference from the given read preference name, list of tag sets, and max allowable staleness of secondaries.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - isSlaveOk
```
public abstract boolean isSlaveOk()
```
    True if this read preference allows reading from a secondary member of a replica set.
    
    Returns:
    
    if reading from a secondary is ok
  - getName
```
public abstract String getName()
```
    Gets the name of this read preference.
    
    Returns:
    
    the name
  - toDocument
```
public abstract BsonDocument toDocument()
```
    Gets a document representing this read preference in the wire protocol.
    
    Returns:
    
    the document
  - choose
```
public final List<ServerDescription> choose(ClusterDescription clusterDescription)
```
    Chooses the servers from the given cluster than match this read preference.
    
    Parameters:
    
    clusterDescription - the cluster description
    
    Returns:
    
    a list of matching server descriptions, which may be empty but may not be null
  - chooseForNonReplicaSet
```
protected abstract List<ServerDescription> chooseForNonReplicaSet(ClusterDescription clusterDescription)
```
  - chooseForReplicaSet
```
protected abstract List<ServerDescription> chooseForReplicaSet(ClusterDescription clusterDescription)
```
  - primary
```
public static ReadPreference primary()
```
    Gets a read preference that forces read to the primary.
    
    Returns:
    
    ReadPreference which reads from primary only
  - primaryPreferred
```
public static ReadPreference primaryPreferred()
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
    
    Returns:
    
    ReadPreference which reads primary if available.
  - secondary
```
public static ReadPreference secondary()
```
    Gets a read preference that forces reads to a secondary.
    
    Returns:
    
    ReadPreference which reads secondary.
  - secondaryPreferred
```
public static ReadPreference secondaryPreferred()
```
    Gets a read preference that forces reads to a secondary if one is available, otherwise to the primary.
    
    Returns:
    
    ReadPreference which reads secondary if available, otherwise from primary.
  - nearest
```
public static ReadPreference nearest()
```
    Gets a read preference that forces reads to a primary or a secondary.
    
    Returns:
    
    ReadPreference which reads nearest
  - primaryPreferred
```
public static ReadPreference primaryPreferred(long maxStaleness,
                                              TimeUnit timeUnit)
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
    
    Parameters:
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads primary if available.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - secondary
```
public static ReadPreference secondary(long maxStaleness,
                                       TimeUnit timeUnit)
```
    Gets a read preference that forces reads to a secondary that is less stale than the given maximum.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads secondary.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - secondaryPreferred
```
public static ReadPreference secondaryPreferred(long maxStaleness,
                                                TimeUnit timeUnit)
```
    Gets a read preference that forces reads to a secondary that is less stale than the given maximumm if one is available, otherwise to the primary.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    *
    
    Parameters:
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads secondary if available, otherwise from primary.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - nearest
```
public static ReadPreference nearest(long maxStaleness,
                                     TimeUnit timeUnit)
```
    Gets a read preference that forces reads to a primary or a secondary that is less stale than the given maximum.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads nearest
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - primaryPreferred
```
public static TaggableReadPreference primaryPreferred(TagSet tagSet)
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to.
    
    Returns:
    
    ReadPreference which reads primary if available, otherwise a secondary respective of tags.\ * @since 2.13
  - secondary
```
public static TaggableReadPreference secondary(TagSet tagSet)
```
    Gets a read preference that forces reads to a secondary with the given set of tags.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary respective of tags.
    
    Since:
    
    2.13
  - secondaryPreferred
```
public static TaggableReadPreference secondaryPreferred(TagSet tagSet)
```
    Gets a read preference that forces reads to a secondary with the given set of tags, or the primary is none are available.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags.
    
    Since:
    
    2.13
  - nearest
```
public static TaggableReadPreference nearest(TagSet tagSet)
```
    Gets a read preference that forces reads to the primary or a secondary with the given set of tags.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads nearest node respective of tags.
    
    Since:
    
    2.13
  - primaryPreferred
```
public static TaggableReadPreference primaryPreferred(TagSet tagSet,
                                                      long maxStaleness,
                                                      TimeUnit timeUnit)
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags that is less stale than the given maximum.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to.
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads primary if available, otherwise a secondary respective of tags.\ * @since 3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - secondary
```
public static TaggableReadPreference secondary(TagSet tagSet,
                                               long maxStaleness,
                                               TimeUnit timeUnit)
```
    Gets a read preference that forces reads to a secondary with the given set of tags that is less stale than the given maximum.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads secondary respective of tags.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - secondaryPreferred
```
public static TaggableReadPreference secondaryPreferred(TagSet tagSet,
                                                        long maxStaleness,
                                                        TimeUnit timeUnit)
```
    Gets a read preference that forces reads to a secondary with the given set of tags that is less stale than the given maximum, or the primary is none are available.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    *
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - nearest
```
public static TaggableReadPreference nearest(TagSet tagSet,
                                             long maxStaleness,
                                             TimeUnit timeUnit)
```
    Gets a read preference that forces reads to the primary or a secondary with the given set of tags that is less stale than the given maximum.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    tagSet - the set of tags to limit the list of secondaries to
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads nearest node respective of tags.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - primaryPreferred
```
public static TaggableReadPreference primaryPreferred(List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or failing if no secondary can be found that matches any of the tag sets in the list.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads primary if available, otherwise a secondary respective of tags.
    
    Since:
    
    2.13
  - secondary
```
public static TaggableReadPreference secondary(List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or failing if no secondary can be found that matches any of the tag sets in the list.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary respective of tags.
    
    Since:
    
    2.13
  - secondaryPreferred
```
public static TaggableReadPreference secondaryPreferred(List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or the primary if none are available.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags.
    
    Since:
    
    2.13
  - nearest
```
public static TaggableReadPreference nearest(List<TagSet> tagSetList)
```
    Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags. The driver will look for a secondary with each tag set in the given list, stopping after one is found, or the primary if none are available.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    Returns:
    
    ReadPreference which reads nearest node respective of tags.
    
    Since:
    
    2.13
  - primaryPreferred
```
public static TaggableReadPreference primaryPreferred(List<TagSet> tagSetList,
                                                      long maxStaleness,
                                                      TimeUnit timeUnit)
```
    Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags that is less stale than the given maximum.
    The driver will look for a secondary with each tag set in the given list, stopping after one is found, or failing if no secondary can be found that matches any of the tag sets in the list.
    
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads primary if available, otherwise a secondary respective of tags.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - secondary
```
public static TaggableReadPreference secondary(List<TagSet> tagSetList,
                                               long maxStaleness,
                                               TimeUnit timeUnit)
```
    Gets a read preference that forces reads to a secondary with one of the given sets of tags that is less stale than the given maximum.
    The driver will look for a secondary with each tag set in the given list, stopping after one is found, or failing if no secondary can be found that matches any of the tag sets in the list.
    
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads secondary respective of tags.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - secondaryPreferred
```
public static TaggableReadPreference secondaryPreferred(List<TagSet> tagSetList,
                                                        long maxStaleness,
                                                        TimeUnit timeUnit)
```
    Gets a read preference that forces reads to a secondary with one of the given sets of tags that is less stale than the given maximum.
    The driver will look for a secondary with each tag set in the given list, stopping after one is found, or the primary if none are available.
    
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - nearest
```
public static TaggableReadPreference nearest(List<TagSet> tagSetList,
                                             long maxStaleness,
                                             TimeUnit timeUnit)
```
    Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags that is less stale than the given maximum.
    The driver will look for a secondary with each tag set in the given list, stopping after one is found, or the primary if none are available.
    
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    tagSetList - the list of tag sets to limit the list of secondaries to
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    ReadPreference which reads nearest node respective of tags.
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)
  - valueOf
```
public static ReadPreference valueOf(String name)
```
    Creates a read preference from the given read preference name.
    
    Parameters:
    
    name - the name of the read preference
    
    Returns:
    
    the read preference
  - valueOf
```
public static TaggableReadPreference valueOf(String name,
                                             List<TagSet> tagSetList)
```
    Creates a taggable read preference from the given read preference name and list of tag sets.
    
    Parameters:
    
    name - the name of the read preference
    
    tagSetList - the list of tag sets
    
    Returns:
    
    the taggable read preference
    
    Since:
    
    2.13
  - valueOf
```
public static TaggableReadPreference valueOf(String name,
                                             List<TagSet> tagSetList,
                                             long maxStaleness,
                                             TimeUnit timeUnit)
```
    Creates a taggable read preference from the given read preference name, list of tag sets, and max allowable staleness of secondaries.
    The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, and selects only those secondaries whose staleness is less than or equal to maxStaleness.
    
    Parameters:
    
    name - the name of the read preference
    
    tagSetList - the list of tag sets
    
    maxStaleness - the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency plus 10 seconds, whichever is greatest.
    
    timeUnit - the time unit of maxStaleness
    
    Returns:
    
    the taggable read preference
    
    Since:
    
    3.4
    
    See Also:
    
    TaggableReadPreference.getMaxStaleness(TimeUnit)

Class ReadPreference

Method Summary

Methods inherited from class java.lang.Object

Method Detail

isSlaveOk

getName

toDocument

choose

chooseForNonReplicaSet

chooseForReplicaSet

primary

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

primaryPreferred

secondary

secondaryPreferred

nearest

valueOf

valueOf

valueOf