Hadoop provides two web interfaces that you should become familiar with, one for HDFS and the other for MapReduce. Both are useful in pseudo-distributed mode and are critical tools when you have a fully distributed setup. The HDFS web UI…
For people coming from RDBMS you must be remembering the alter table command for dropping/adding columns in a table. In MongoDB it is possible to do this operation on some of the documents (rows) or all documents together. There is…
Replication gives you hot backups, read scaling, and all sorts of other goodness. If you know how it works you can get a lot more out of it, from how it should be configured to what you should monitor to…
Do you have issues with you SSH in your lab/test VMs which has no proper builds and thus it’s effecting SSH Tectia functionality. No issues, below works for me – please have a try. Not sure how far this is…
MongoDB graceful shutdown script. [root@hostname bin]$ cat new_shutdown.sh #!/bin/bash BIN=/tmp/mongodb/bin DB=admin HOST=`hostname` cd $BIN MONGOPID=`ps -ef | egrep ‘mongod|mongos’ | grep -v egrep | awk ‘{print $2}’` if [ -z $MONGOPID ]; then echo “There are no Mongo processes are…
The following factors influence the Initial sync & sharding timings i.e., the initial sync between primary and secondary for a replica set or the initial sharding/balancing for a sharded cluster 1. Document size 2. No. of documents/collections 3. No….
This is a custom implementation created by the MongoDB developers as a specific index type, and is due to be launched as an experimental feature in MongoDB 2.4. It has features such as: Full text search as an index type…
We observed that inconsistent document counts of a collection when we query thru mongos during initial sharding due to newly added shard to the existing set-up. It’s expected to have inconsistent counts when we query directly on shard, but App…
While there are no built in commands for lock/unLock, it is possible to add them. Here are a couple of simple implementations that remove the user you want to lock from the db.system.users collection and save it in a lockedUsers…
If we create a user in Mongos (router), we can authenticate Mongod’s (RS/Shard: in case of shard, user should have ‘clusterAdmin’ role) using that user. But still we can directly connect to Mongod’s with localhost exception with out any UN/PW….