Sunday, August 16, 2015

Black screen after latest win 8.1 updates



1) sfc /scannow
and
2) dism.exe /online /cleanup-image /scanhealth

to see if there is any corruption.

If none, then try updating after disabling all non-windows services and all startup programs listed by Task Manager (reboot after disabling and then update).

Thursday, August 13, 2015

Difference between SQL and NOSQL Databases.

SQL databases are like automatic transmission and NoSQL databases are like manual transmission. Once you switch to NoSQL, you become responsible for a lot of work that the system takes care of automatically in a relational database system. Similar to what happens when you pick manual over automatic transmission. Secondly, NoSQL allows you to eke more performance out of the system by eliminating a lot of integrity checks done by relational databases from the database tier. Again, this is similar to how you can get more performance out of your car by driving a manual transmission versus an automatic transmission vehicle.

However the most notable similarity is that just like most of us can’t really take advantage of the benefits of a manual transmission vehicle because the majority of our driving is sitting in traffic on the way to and from work, there is a similar harsh reality in that most sites aren’t at Google or Facebook’s scale and thus have no need for a Bigtable or Cassandra.

These are some points which gives us some difference between SQL and NOSQL Databases.


  • SQL databases are primarily called as Relational Databases (RDBMS); whereas NoSQL database are primarily called as non-relational or distributed database.
  • SQL databases have predefined schema whereas NoSQL databases have dynamic schema for unstructured data.
  • SQL databases are vertically scalable whereas the NoSQL databases are horizontally scalable. SQL databases are scaled by increasing the horse-power of the hardware.
  • In case of scalability: In most typical situations, SQL databases are vertically scalable. You can manage increasing load by increasing the CPU, RAM, SSD, etc, on a single server. On the other hand, NoSQL databases are horizontally scalable. You can just add few more servers easily in your NoSQL database infrastructure to handle the large traffic.
  • For complex queries: SQL databases are good fit for the complex query intensive environment whereas NoSQL databases are not good fit for complex queries. On a high-level, NoSQL don’t have standard interfaces to perform complex queries, and the queries themselves in NoSQL are not as powerful as SQL query language.

Reference from : link