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MongoDB. Lugar y Fecha. Telefónica I+D. Mongodb is. A document-oriented storage . JSON- style documents with dynamic schemas offer simplicity and power . Querying . Rich , document -base queries . Fast In-Place Updates . Atomic modifiers for contention -free performance. - PowerPoint PPT Presentation
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MongoDB
Telefónica I+D
Lugar y Fecha
Telefónica I+D 2
Mongodb is...
A document-oriented storage.JSON-style documents with dynamic schemas offer simplicity and power.
Querying.Rich, document-base queries.
Fast In-Place Updates.Atomic modifiers for contention-free performance.
Full index Support.Index on any attribute.
Auto-Sharding.Scale horizontally without compromising funcionality.
Replication & High Availability.Mirror across LAN for scale.
Map/ReduceFlexible (but limited) data processing.
Telefónica I+D 3
Mongodb is Not...
A ACID database.
A batch procesing platform.
Telefónica I+D 4
Mongodb Architecture
MongoDB is a document-oriented database, but this not implica that it has the same concepts of RDMS, one of this concepts is the “database”, within a MongoDB instance you can have zero or more databases, each acting as high-level containers for everything else
A database can have zero or more “collections”, A collection shares enough in common with a traditional table, a collection is the same as a table with a indeterminate number of columns.
Collections is made up of zero or more documents. Again, a document can safely be thought of as a “row”.
A document is made up one or more fields, which yo can probable guess are a lot like “columns”.
Indexes in MongoDB function much like their RDBMS counterparts.
Cursors are different than the other five concepts but they are important enough. The import thing to understand about cursors is that when you ask MongoDB for data, it returns a cursor, which we can do things to, such as counting or skipping ahead, without actually pulling down data.
Telefónica I+D 5
Mongodb Architecture
Mongo uses memory mapped files to access data, which results in large numbers being displayed in tools like top for the mongod process.
Mongo eliminates the need (in some cases) for a separate object caching layer. Queries that result in file system RAM cache hits are very fast as the object's representation in the database is very close to its representation in application memory. Also, the MongoDB can scale to any level and provides an object cache and database integrated together, which is very helpful as there is no risk of retrieving stale data from the cache. In addition, the complex queries a full DBMS provides are also possible.
MongoDB supports write-ahead journaling of operations to facilitate fast crash recovery and durability in the storage
Telefónica I+D 6
Mongodb Api
Data Type Type Number
Double 1
String 2
Object 3
Array 4
Binary data 5
Object id 7
Boolean 8
Date 9
Null 10
Regular Expresion 11
Telefónica I+D 7
Mongodb Api
The conection to the databases front the aplications are a propiatery protocol that runs over TCP/IP in binary format. The apis have a control the write behavior for with various options, as well as exception raising on error conditions. NONE: No exceptions are raised, even for network issues
NORMAL: Exceptions are raised for network issues, but not server errors
SAFE: Exceptions are raised for network issues, and server errors; waits on a server for the write operation
FSYNC_SAFE: Exceptions are raised for network issues, and server errors and the write operation waits for the server to flush the data to disk
REPLICAS_SAFE: Exceptions are raised for network issues, and server errors; waits for at least 2 servers for the write operation
Telefónica I+D 8
Mongodb Api
Insert: it is the basic method for adding data into MongoDB. When we insert a new document into a collection this will add an “_id” key to the document before save it. When insert a new object into the collection, the driver coverts the data structure into BSON, which it then sends to the database. Then it saves the document, and regenerate the _id index, and all the secondary index that the new object has.
db.collection.insert(doc);
db.collection.save(doc); // updates if exists; inserts if new (_id)
Delete: it is the basic method for deleting data. db.videos.remove( { rating : { $lt : 3.0 }, $atomic : true } )
Telefónica I+D 9
Mongodb Api
Query: MongoDB's support for dynamic (ad hoc) queries. MongoDB supports a number of query objects for fetching data.
Db.collection.find(query,fields)
Method: count()
sort()
limit()
skip()
Telefónica I+D 10
Mongodb Api
Query Modifier Operations
$gt (>) , $gte(>=), $lt (<), $gle(<=) db.collection.find({ "field" : { $gt: value } } );
$all db.things.find( { a: { $all: [ 2, 3 ] } } );
$exists db.things.find( { a : { $exists : true } } ); present
$mod db.things.find( { a : { $mod : [ 10 , 1 ] } } )
$ne db.things.find( { x : { $ne : 3 } } );
$in db.things.find({j:{$in: [2,4,6]}});
$nin db.things.find({j:{$nin: [2,4,6]}});
$or db.foo.find( { $or : [ { a : 1 } , { b : 2 } ] } )
$size db.things.find( { a : { $size: 1 } } );
$type db.things.find( { a : { $type : 2 } } );
$elemMatch t.find( { x : { $elemMatch : { a : 1}})
$regex db.customers.find( { name : { $regex : 'acme.*corp', $options: 'i' } } );
$where db.myCollection.find( { $where: "this.a > 3" } );
Telefónica I+D 11
Mongodb Api
Update: replaces the document matching criteria entirely with objNew. If you only want to modify some fields, you should use the atomic modifiers below.
db.collection.update( criteria, objNew, upsert, multi ).
Arguments criteria - query which selects the record to update;
objNew - updated object or $ operators (e.g., $inc) which manipulate the object
upsert - if this should be an "upsert"; that is, if the record does not exist, insert it
multi - if all documents matching criteria should be updated
Telefónica I+D 12
Mongodb Api
Update Modifier Operations$inc { $inc : { field : value } }
$set { $set : { field : value } }
$unset { $unset : { field : 1} }
$push { $push : { field : value } }
$pushAll { $pushAll : { field : value_array } }
$addToSet { $addToSet : { field : value } }
$pop { $pop : { field : 1 } }{ $pop : { field : -1 } }
$pull { $pull : { field : _value } }
$pullAll { $pullAll : { field : value_array } }
$rename { $rename : { old_field_name : new_field_name } }
$bit {$bit : {field : {and : 5, or : 2}}}
$ ( positional number) {$inc:{'comments.$.votes':1}}
Telefónica I+D 13
Mongodb Api
Upserts : it is a special type of update, in where if no document is found to upate, a new document will be created in a atomic operation.
db.jobs.findAndModify({query: {},update : {}, fields: {}, new: false } )
Arguments
Query {}
Sort {}
Remove N/A
Update N/A
New False
Fields All fields
upsert False
Telefónica I+D 14
Mongodb Api
Example in console.
Telefónica I+D 15
Mongodb Index
These indexes are implemented as "B-Tree" indexes.
the indexes in MongoDB work a lot like indexes in a relational database: they help improve query and sorting performance, the indexes are created manual, and could be unique, ascending or descending.
Index on _id is always created and can`t be deleted.
I can index on a key inside of an embedded document.
Telefónica I+D 16
Mongodb Index
Example in console.
Telefónica I+D 17
Mongodb Sharding
MongoDB supports auto-sharding, and auto.balancing.
Sharding is an approach to scalability which separates your data across multiple servers.
With sharding we instead scale horizontally to achieve the same computacional/storage/memory footprint from smaller servers.
We will show the vertically scale db and the horizontally scaled db for comparison.
A sharded collection has a shard key. The collection is partitioned using this key. In this example we uses ident.
{ident:…, data:…}
Telefónica I+D 18
Mongodb Sharding
There are three components in sharding.
Mongos: routing procesing.
Config servers: store the metadata.
Mongod: store the data.
Range ShardIdent in [-inf,200) 2
Ident in (200, 400] 4
…
Ident in [1000,inf) 10
Telefónica I+D 19
Mongodb Sharding
Metadata is maintained on chunks which are represented by shard key ranges.
Range ShardIdent in [-inf,200) 2
Ident in (200, 400] 4
…
Ident in [1000,inf) 10
Telefónica I+D 20
Mongodb Sharding
Querys with the shard key are sent to the node who has this shard.
Query ShardsFind({ident :{$gt 100, $lt:150}) 2
Telefónica I+D 21
Mongodb Sharding
Querys with the shard key and the data are in some shard, it as sent to these nodes.
Query ShardsFind({ident :{$gt 100, $lt:250}) 2,3
Telefónica I+D 22
Mongodb Sharding
Querys with the no shard key are sent to all nodes.
Query ShardsFind({data:{$gt 100, $lt:250}) 2,3
Telefónica I+D 23
Mongodb Sharding
Example in console.
Telefónica I+D 24
Mongodb Replication
MongoDB replication works similarly to how relational database replication works. Writes are sent to a single server, the master, which then synchronizes itself to one or more other servers, the slaves. If the master goes down, a slave can be promoted to act as the new master.
While replication can improve performance (by distributing reads), its main purpose is to increase reliability.
There are two types of replication:
Master slaver replication.
Replica sets.
Telefónica I+D 25
Mongodb Replication
Master slaver replication.
Setup master: bin/mongod –master –oplogSize 100
Setup slaver: bin/mongod --slave --source <IP>[:<port>] --slavedelay 1 --autoresync
Telefónica I+D 26
Mongodb Replication
Replica sets. mongod --replSet “setname”
Shell in one nodecfg = {
... _id : “setname",
... members : [
... { _id : 0, host : “host1" },
... { _id : 1, host : “host2" },
... { _id : 2, host : “host3" } ] }
rs.initiate(cfg)
rs.status()
Options
arbiterOnly buildIndexes
hidden priority
slaveDelay votes
tags
Telefónica I+D 27
Mongodb Map&Reduce
DB is useful for batch processing of data and aggregation operations.
Telefónica I+D 28
Mongodb Tools
Mongodump: export to binary data
Mongoexport: export to csv
Mongofiles: load data into mongodb
MongoImport: import txt, csv or json data
mongoRestore: mongorestore takes the output from mongodump: and restores it.
mongoSniff: This utility is to MongoDB what tcpdump is to TCP/IP
Mongostat: Use the mongostat utility to quickly view statistics on a running mongod instance