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Common MongoDB Topologies: A Guide to Sharding, Replication, and Backup Strategies



mongodump --ssl --host=localhost --port=33444 -u="User" -p="Password" --sslPEMKeyFile=/etc/ssl/mongodb/client/client.pem --sslCAFile=/etc/ssl/mongodb/server/server.pem --sslPEMKeyPassword=password --db=mydb --archive=./backups/backup_time.gz --gzip




Common MongoDB Topologies



storm-mongodb includes a general purpose MongoMapper implementation called SimpleMongoMapper that can map Storm tuple to a Database document. SimpleMongoMapper assumes that the storm tuple has fields with same name as the document field name in the database collection that you intend to write to.


To use the MongoInsertBolt, you construct an instance of it by specifying url, collectionName and a MongoMapper implementation that converts storm tuple to DB document. The following is the standard URI connection scheme: mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]


storm-mongodb includes a general purpose MongoUpdateMapper implementation called SimpleMongoUpdateMapper that can map Storm tuple to a Database document. SimpleMongoUpdateMapper assumes that the storm tuple has fields with same name as the document field name in the database collection that you intend to write to.SimpleMongoUpdateMapper uses $set operator for setting the value of a field in a document. More information about update operator, you can visit


storm-mongodb includes a general purpose QueryFilterCreator implementation called SimpleQueryFilterCreator that can create a MongoDB query Filter by given Tuple. QueryFilterCreator uses $eq operator for matching values that are equal to a specified value. More information about query operator, you can visit


We support trident persistent state that can be used with trident topologies. To create a Mongo persistent trident state you need to initialize it with the url, collectionName, the MongoMapper instance. See the example below:


The comma-separated list of hostname and port pairs (in the form 'host' or 'host:port') of the MongoDB servers in the replica set. The list can contain a single hostname and port pair. If mongodb.members.auto.discover is set to false, then the host and port pair should be prefixed with the replica set name (e.g., rs0/localhost:27017).


Specifies a connection string that the connector uses during the initial discovery of a MongoDB replica set.To use this option, you must set the value of mongodb.members.auto.discover to true.Do not set this property and the mongodb.hosts property at the same time.


The connector uses this connection string only during the initial replica set discovery process.During this discovery process, the connector ignores connection values that are specified in other properties (mongodb.user, mongodb.password, mongodb.authsource, SSL configuration properties, and so forth).After the discovery process completes, when the connector attempts to establish a direct connection to a primary replica set member, the connector then returns to using the standard connection properties,and it ignores values in mongodb.connection.string.However, if credential information is not present elsewhere in the configuration, the connector can extract credential information from the value of the connection string.For example, if the mongodb.user property is not set, but the connection string includes the MongoDB username, the connector reads the information from the string.


Boolean value that specifies whether the addresses in 'mongodb.hosts' are seeds that should be used to discover all members of the cluster or replica set (true), or whether the address(es) in mongodb.hosts should be used as is (false). The default is true and should be used in all cases except where MongoDB is fronted by a proxy.


The connector configuration property mongodb.name serves as a logical name for the MongoDB replica set or sharded cluster. The connector uses the logical name in a number of ways: as the prefix for all topic names, and as a unique identifier when recording the oplog position of each replica set.


The MongoDB connector writes events for all insert, update, and delete operations to documents in each collection to a single Kafka topic. The name of the Kafka topics always takes the form logicalName.databaseName.collectionName, where logicalName is the logical name of the connector as specified with the mongodb.name configuration property, databaseName is the name of the database where the operation occurred, and collectionName is the name of the MongoDB collection in which the affected document existed.


The comma-separated list of hostname and port pairs (in the form 'host' or 'host:port') of the MongoDB servers in the replica set. The list can contain a single hostname and port pair. If mongodb.members.auto.discover is set to false, then the host and port pair should be prefixed with the replica set name (e.g., rs0/localhost:27017).


I have the same problem, connecting to the MongoDB database.MongooseServerSelectionError: Could not connect to any servers in your MongoDB Atlas cluster. One common reason is that you're trying to access the database from an IP that isn't whitelisted. Make sure your current IP address is on your Atlas cluster's IP whitelist: -whitelist/


The database representation is 9.99 as an IEEE floating point (whichis common to MongoDB and Python as well as most other modernlanguages). The problem is that 9.99 cannot be represented exactlywith a double precision floating point - this is true in some versions ofPython as well:


There are different types of topological errors and they can be grouped accordingto whether the vector feature types are polygons or polylines. Topological errorswith polygon features can include unclosed polygons, gaps between polygonborders or overlapping polygon borders. A common topological error withpolyline features is that they do not meet perfectly at a point (node). Thistype of error is called an undershoot if a gap exists between the lines, andan overshoot if a line ends beyond the line it should connect to (seeFig. 7.12).


Except for some special GIS data formats, topology is usually not enforced bydefault. Many common GIS, like QGIS, define topology as relationship rules andlet the user choose the rules, if any, to be implemented in a vector layer.


Another topological option allows you to prevent** polygon overlaps** duringdigitising (see Fig. 7.13 (2)). If you already have one polygon,it is possible with this option to digitise a second adjacent polygon so thatboth polygons overlap and QGIS then clips the second polygon to the commonboundary.


MySQL replication has been available for years, and even though a number of new clustering technologies showed up recently, replication is still very common among MySQL users. It is understandable as replication is a reliable way of moving your data between MySQL instances. Even if you use Galera or NDB cluster, you still may have to rely on MySQL replication to distribute your databases across WAN.


As you can imagine, replication topology changes and failover processes are common operations, albeit complex. In future posts, we will discuss rolling MySQL upgrades and migrations between different environments. As we mentioned earlier, even if you use Galera or NDB Cluster you may need to use replication to connect different datacenters or providers over a WAN, and eventually perform the standard planned failover process that we described above.


The mongodb-topology-manager npm package is indispensible for testing MongoDB connection logic. This lib can stop and start MongoDB servers, replica sets, and sharded clusters from Node.js. The MongoDB driver Node.js uses it for testing internally.


HVR supports data replication across multiple heterogeneous systems. Below are basic replication topologies that allow you to construct any type of replication scenario to meet your business requirements.


This topology involves unidirectional data replication from a source location to a target location. This type of topology is common when customers look to offload reporting, feeding data lakes, and populating data warehouses. 2ff7e9595c


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