You can make Left Join in MongoDB ?
Most will say no , because it is NoSQL ( free of schemas and joins ) . But from the new version of MongoDB (3.2) , the answer is YES! Visit the blog… We all know that one of…
MongoDB: Defragmentation testing
[dbversit@dbversity bin]$ ps -ef | grep mongo | grep -v grep dbversit 6471 1 0 04:55 ? 00:00:45 ./mongod –configsvr –dbpath /tmp/mongodb/config1 –logpath /tmp/mongodb/logs/config.log –port 30001 –config /etc/mongod.conf dbversit 7165 1 3 05:00 pts/2 00:07:47 ./mongod –shardsvr –replSet rs –dbpath…
Why MongoDB have variant fragmented space in a same ReplicaSet members ?
Why MongoDB have variant fragmented space in a same ReplicaSet members ? When we’ve 3 node replica set (PSS) and do have bulk updates and delete operations, though they’ll be in sync through same OpLog mechanism – why do I…
mongoimport of a JSON Array with ‘to’ field got issues ?!!
While importing attached JSON array as below, I see below errors – Sample records from the JSON file are below. [{ “_id” : { “$oid” : “52fa519da6342a0dcd97222a” }, “active” : true, “from” : { “$date” : “2000-01-01T00:00:00.000-0500” }, “kind” :…
MongoDB Compass Overview
With MongoDB Compass, you can visually explore your data and run ad-hoc queries in seconds. Compass empowers you to make smarter decisions about indexing, document validation, and more. No command line needed Screen shots : MongoDB_Compass_Overview Know your data with…
MariaDB’s RHEL package installation
[ root @ dbversity : /home/mariadb ] ll -lhtr total 29M -rw-r–r– 1 root root 1.6K May 19 05:45 install -rw-r–r– 1 root root 25K May 19 05:45 rh-mariadb101-mariadb-config-10.1.13-1.el6.x86_64.rpm -rw-r–r– 1 root root 60K May 19 05:45 rh-mariadb101-mariadb-common-10.1.13-1.el6.x86_64.rpm -rw-r–r– 1…
DBVersity MongoDB Assessment tests
Download at : DBVersity_MongoDB_Assessment_papers DBVersity MongoDB Assessment MongoDB manages collections of _________ like documents which are internally stored in binary format referred to as BSON? XML JavaScript HTML JSON All of above Purpose of MongoDB Replication…
Tracking document versions with MongoDB
Consider requirement that we have to be able to recreate/query any version of a document that ever existed in a particular collection. So we start out with: { docId: “A”, version: 1, color: “red”, locale: “USA” } If we need…
findAndModify()
Quick question – on findAndModify() concurrency. Ex: 2 threads are trying to pull the same document at the same time (using status=pending), and assuming 1st thread gets the lock on the doc and change the status to “in-process” through findAndModify()….
Working with MongoDB Indexes
Indexes are the single biggest tunable performance factor in MongoDB Absent or suboptimal indexes are the most common avoidable MongoDB performance problem. // Create an index if one does not exist db.recipes.ensureIndex ( { main_ingredient : 1 } ) //…