What are popular / good NoSQL databases?
What are the popular / good NoSQL databases nowadays?
MongoDB, CouchDB
Find more at https://en.wikipedia.org/wiki/NoSQL and http://nosql-database.org/
What are the popular / good NoSQL databases nowadays?
MongoDB, CouchDB
Find more at https://en.wikipedia.org/wiki/NoSQL and http://nosql-database.org/
In memory hierarchical, it needs to be coherence and consistency. However, they are different things. What are the differences? Memory coherence: a memory system is coherent if any read of a data item returns the most recently written value of that data item (what values can be returned by a read). Memory consistency: A memory…
ssh client can use many authentication methods like password, keys. On a server, I set password-less log in with private/public key. Now, I want to try whether the new password is set correctly by log on using ssh. By default, the key-based authentication method is used again. How to force ssh client to authenticate using…
How to test whether a user account, say linuxuser, already exist on Linux? You may make use of id which tries to get user IDs. The Bash code snippet is as follows. user=hello id -u $user >/dev/null 2>&1 if [ “$?” == “0” ]; then echo “user $user already exist.” else echo “user $user doesn’t…
The public cloud storage services like Amazon S3, Google Cloud Storage and Windows Azure Storage replicate the data to ensure high availability. On the other hand, with data being replicated, the storage services exhibits certain data consistency models. Different cloud service providers employ different data consistency models nowadays. In this post, we survey the data…
How to list the functions in a .a library on Linux? You can use the nm command: The nm utility shall display symbolic information appearing in the object file, executable file, or object-file library named by file. If no symbolic information is available for a valid input file, the nm utility shall report that fact,…
I know the routing tables on Linux is in memory after being set. However, where are the routing table entries stored on disk? I mean where are the routing table is persistently stored so that the routing table can be reloaded like the iptables (under /etc/sysconfig/iptables on Fedora/RHEL/CentOS Linuxes). If the system uses the /etc/rc.d/init.d/network…