What is Readpreference in MongoDB?
Read preference describes how MongoDB clients route read operations to the members of a replica set. By default, an application directs its read operations to the primary member in a replica set (i.e. read preference mode “primary”). But, clients can specify a read preference to send read operations to secondaries.
What are tags in MongoDB?
A tag set is an array of tag specification documents, where each tag specification document contains one or more tag/value pairs. To find replica set members, MongoDB tries each document in succession until a match is found. See Order of Tag Matching for details.
What is the MongoDB command required to allow the secondary server to allow reads?
setSlaveOk()
As MongoDB documented setSlaveOk() This allows the current connection to allow read operations to run on secondary members.
Which of the following should not be used to provide extra capacity for reads?
In general, do not use secondary and secondaryPreferred to provide extra capacity for reads, because: All members of a replica have roughly equivalent write traffic; as a result, secondaries will service reads at roughly the same rate as the primary.
What is replica set MongoDB?
A replica set in MongoDB is a group of mongod processes that maintain the same data set. Replica sets provide redundancy and high availability, and are the basis for all production deployments. This section introduces replication in MongoDB as well as the components and architecture of replica sets.
How does replica set connect to MongoDB?
To connect to a replica set, include a seedlist of replica set members and the name of the replica set in the URI connection string. In the following example, the connection string specifies two of the replica set members running on localhost:27017 and localhost:27018 and the name of the replica set ( foo ).
What is tag set?
A tag set is an array of documents, where each document contains the tag and value pair(s). The specifications are tried in order until a match is found. Once found, that specification is used to find all eligible matching members.
How do you implement tags?
Click Tags from the navigation menu.
- To add a tag: Click New. Select the tag type and specify triggers for when the tag should fire.
- To edit a tag: Click a tag in the list and make changes on the “Edit Tag” page.
- To delete a tag: Click a tag in the list.
How do I run Mongodump?
Run mongodump from the system command line, not the mongo shell.
- Connect to a MongoDB Instance. To connect to a local MongoDB instance running on port 27017 and use the default settings to export the content, run mongodump without any command-line options:
- Connect to a Replica Set.
- Connect to a Sharded Cluster.
What is a MongoDB replica set?
How many types of members exist in replica set?
How many types of members exist in replica set? Explanation: There are two members in replica set-primary and secondary.
Why do we need replica set in MongoDB?
Replica sets provide redundancy and high availability, and are the basis for all production deployments. This section introduces replication in MongoDB as well as the components and architecture of replica sets. The section also provides tutorials for common tasks related to replica sets.
When to use the nearest read preference mode?
If low latency reads are required, use the NEAREST read preference mode. This setting directs the read operations to the nearest available region. Note that if the nearest region is the WRITE region, then these operations are directed to that region.
When to use read preference in a transaction?
Read Preference and Transactions ΒΆ Multi-document transactions that contain read operations must use read preference primary. All operations in a given transaction must route to the same member.
Is the read preference mode compatible with tag sets?
The primary read preference mode is not compatible with read preference modes that use tag sets or maxStalenessSeconds . If you specify tag sets or a maxStalenessSeconds value with primary, the driver will produce an error. Multi-document transactions that contain read operations must use read preference primary.
When to use primary preferred read preference in azure?
If high availability and geo distribution of reads are required (latency is not a constraint), then use the PRIMARY PREFERRED or SECONDARY PREFERRED read preference mode. This setting directs read operations to an available WRITE or READ region respectively.
