Mongodb – wikipedia

The software company 10gen began developing MongoDB in 2007 as a component of a planned platform as a service product. Icare data recovery In 2009, the company shifted to an open source development model, with the company offering commercial support and other services. Data recovery jacksonville fl In 2013, 10gen changed its name to MongoDB Inc. 510 k database search [5] Main features [ edit ] Ad hoc queries

MongoDB supports field, range queries, regular expression searches. Database engineer [6] Queries can return specific fields of documents and also include user-defined JavaScript functions.


Data recovery california Queries can also be configured to return a random sample of results of a given size. Moto x data recovery Indexing

MongoDB provides high availability with replica sets. Database administrator [7] A replica set consists of two or more copies of the data. Database acid Each replica set member may act in the role of primary or secondary replica at any time. Database 10g All writes and reads are done on the primary replica by default. Database news Secondary replicas maintain a copy of the data of the primary using built-in replication. Database key value When a primary replica fails, the replica set automatically conducts an election process to determine which secondary should become the primary. Data recovery pro review Secondaries can optionally serve read operations, but that data is only eventually consistent by default. Data recovery windows 8 Load balancing

MongoDB scales horizontally using sharding. Data recovery devices [8] The user chooses a shard key, which determines how the data in a collection will be distributed. Moto g data recovery software The data is split into ranges (based on the shard key) and distributed across multiple shards. Data recovery windows 10 (A shard is a master with one or more slaves.). Database youtube Alternatively, the shard key can be hashed to map to a shard – enabling an even data distribution.

MongoDB can run over multiple servers, balancing the load or duplicating data to keep the system up and running in case of hardware failure. H2 database console File storage

This function, called Grid File System, [9] is included with MongoDB drivers. Database browser MongoDB exposes functions for file manipulation and content to developers. Database help GridFS is used in plugins for NGINX [10] and lighttpd. Database vendors [11] GridFS divides a file into parts, or chunks, and stores each of those chunks as a separate document. Database key [12] Aggregation

The aggregation framework enables users to obtain the kind of results for which the SQL GROUP BY clause is used. Data recovery live cd Aggregation operators can be strung together to form a pipeline – analogous to Unix pipes. Data recovery clean room The aggregation framework includes the $lookup operator which can join documents from multiple documents, as well as statistical operators such as standard deviation. Database view Server-side JavaScript execution

JavaScript can be used in queries, aggregation functions (such as MapReduce), and sent directly to the database to be executed. Data recovery fort lauderdale Capped collections

MongoDB supports fixed-size collections called capped collections. Data recovery equipment tools This type of collection maintains insertion order and, once the specified size has been reached, behaves like a circular queue. Data recovery lab Bug reports and criticisms [ edit ]

As of January 2017, data from tens of thousands of MongoDB installations has been stolen and is being held for ransom. Data recovery online This appears to be because when “installed on a server with the default settings … Database union MongoDB allows anyone to browse the databases, download them, or even write over them and delete them.” Furthermore late-coming extortionists are overwriting the demands of the original extortionists. Data recovery houston Therefore database owners who decide to pay the ransom will make payments to people who don’t have the original data, so the data is not restored even though the ransom is paid. 7m database soccer basketball [13] In other instances, the original extortionist did not copy the database before deletion, so the victim will not get their data back even if they pay. Create database link [14]

In some failure scenarios where an application can access two distinct MongoDB processes, but these processes cannot access each other, it is possible for MongoDB to return stale reads. Database form In this scenario it is also possible for MongoDB to roll back writes that have been acknowledged. Data recovery process [15]

Before version 2.2, concurrency control was implemented on a per-mongod basis. Database training With version 2.2, concurrency control was implemented at the database level. Data recovery hardware [16] Since version 3.0, [17] pluggable storage engines were introduced, and each storage engine may implement concurrency control differently. Best database software [18] With MongoDB 3.0 concurrency control is implemented at the collection level for the MMAPv1 storage engine, [19] and at the document level with the WiredTiger storage engine. Database gui [20] With versions prior to 3.0, one approach to increase concurrency is to use sharding. Data recovery technician [21] In some situations, reads and writes will yield their locks. Database engine tuning advisor If MongoDB predicts a page is unlikely to be in memory, operations will yield their lock while the pages load. Data recovery rates The use of lock yielding expanded greatly in 2.2. Database developer salary [22]

Another criticism is related to the limitations of MongoDB when used on 32-bit systems. Database backup and recovery [23] In some cases, this was due to inherent memory limitations. Yale b database [24] [ self-published source] MongoDB recommends 64-bit systems and that users provide sufficient RAM for their working set.

Up until version 3.3.11, MongoDB could not do collation-based sorting and was limited to byte-wise comparison via memcmp, [25] which would not provide correct ordering for many non-English languages [26] when used with a Unicode encoding. Sybase database The issue was fixed on August 23, 2016.

MongoDB queries against an index are not atomic and can miss documents which are being updated while the query is running and match the query both before and after an update. Database design [27] Architecture [ edit ] Programming language accessibility [ edit ]

MongoDB has official drivers for a variety of popular programming languages and development environments. Database 3 normal forms [28] There are also a large number of unofficial or community-supported drivers for other programming languages and frameworks. Database for dummies [29] Management and graphical front-ends [ edit ]

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